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Captain M. A. Ainslie, (1869-1951): his observations and telescopes.

Maurice Anderson Ainslie, perhaps better known to BAA historians as Captain Ainslie, or simply 'The Skipper', was a colourful and energetic BAA character as well as being a member of the Association for 45 years. He was born on 1869 October 4, the youngest son of Archdeacon Alexander ColvinAinslie (1831-1903) of Langport, Somerset. In addition to serving as the Association's twentieth President from 1928 to 1930, following W. H. Steavenson (18941975) and preceding Major A. E. Levin (1872-1939), Ainslie conceived the Methods of Observation Section (nowadays roughly equivalent to the Instruments & Imaging Section) and served as its first director from 1917 to 1932. Before detailing Ainslie's astronomical achievements it might be better to start by setting the scene and simply quoting Steavenson's description of the man, from his obituary, (1) as follows:


'Impressive' is, perhaps, the word which most aptly describes Ainslie's appearance and personality. Above the average height, he was built on massive lines and seemed somewhat to dominate any gathering at which he was present. His manner was nearly always bluff and genial and his great frame was often to be seen convulsed with laughter, for he had a very strong sense of humour. By nature gregarious, he was the most sociable of men, and frankly enjoyed the pleasures of good food and good company; and to him good company meant that of his brother amateurs. On certain subjects he held very definite views, in their expression of which he was apt to be rather outspoken and on occasion his beard seemed to bristle and his usually jovial countenance would assume a decidedly formidable expression. But there was nevertheless something simple and child-like in his character which was attractive to his friends, who could appreciate his point of view and make allowances for what a stranger might have taken for mere prejudice; for he was above everything wholehearted and sincere in all his actions and opinions.'

Not surprisingly, given his title, the bearded and large framed Captain Ainslie (see Figure 1) had a seafaring background and so his BAA nickname of 'The Skipper' was very appropriate. After an education at Marlborough, and then graduating in Mathematics and Natural Science from Caius College Cambridge in 1891, Ainslie initially adopted teaching as a profession. He became an assistant master at Derby school and later taught at Giggleswick (over which the solar eclipse of 1927 would famously pass more than thirty years later). However in 1894 he switched professions and became a different type of teacher, in the Instructional Branch of the Royal Navy. On his retirement in 1922, while only in his early fifties, he held the rank of Instructor-Captain. According to Steavenson's obituary, in his 28 years with the Navy Ainslie had served with the Mediterranean, Channel and Cruiser squadrons and at the Royal Naval College at Greenwich. In astronomical papers Ainslie often described himself as Naval-Instructor M. A. Ainslie, R. N., B. A. or simply Instructor-Captain Ainslie, but in the BAA of the early 20th century he was invariably known to his colleagues as 'The Skipper'.

Astronomical beginnings

Ainslie was elected to the Royal Astronomical Society in 1893, when aged only 23. He joined the BAA thirteen years later. But his interest in astronomy had existed well before he joined the RAS. Again, according to Steavenson's obituary of 'the Skipper', Ainslie had enjoyed the use of a 4-inch (102mm) Cooke refractor, owned by Marlborough College, in his schooldays. With this telescope and a copy of Webb's Celestial Objects the young master Ainslie was well equipped. Although he enjoyed access to the 12-inch (305mm) Northumberland Refractor while at Cambridge, and a more modest refractor at his Giggleswick teaching post, he found himself without a telescope on entering the Navy in 1894. However he seems to have acquired various instruments in the following years, namely a 31/2-inch (89mm) refractor and a 61/2-inch (165mm) Calver reflector. In addition he attempted to grind and polish both a 6-inch (152mm) and a 12-inch (305mm) Newtonian mirror around the time he joined the Navy.


Ainslie's earliest surviving observing logbook, of 1903, was originally held by Bill Day, but is now in the possession of David Strange. This same logbook records observations of double stars, nebulae, planets and other objects, such as comet Brooks of 1904. For example, one of the earliest deep sky entries reads: Feb 28th 1903. Spiral Nebula in Canes Venatici seen well, two nebula in connection with suspicion of an outer ring.

Ainslie seems to have decided to move up in aperture in 1903, the year of his Archdeacon father's death, and his observing log gives a daily account of his refiguring, testing and silvering of a 9-inch (229mm) 'spec', that is a 9-inch mirror, while he lived in Devon. This was his third attempt at mirror making and was ultimately very successful, with Steavenson describing the final figure as 'excellent'. In fact, strictly speaking, this mirror was his fourth attempt at mirror making as he made two 9-inch examples in quick succession; the first was 1-inch (25mm) thick and the second 1//inches (38mm) thick, and he also made two tubes during the course of the project. The focal length of the completed 9-inch Newtonian, the best of the two, was 78 inches (1.98 metres), making the instrument almost f/8.7. Ainslie mounted the new mirror in a square mahogany tube, half an inch thick and with an internal diameter of 10 inches (he would have preferred 101/2 inches in hindsight), atop an altazimuth stand that he had previously used for his 61/2-inch (165mm) Calver. The new telescope was affectionately known as 'William' after the great William Herschel. It would appear that this 9-inch reflector was Ainslie's last attempt at polishing a mirror for his own use, as he used that instrument for the next 30 years.


From the English Mechanic to the BAA

Ainslie published many practical letters and articles on telescope construction in the English Mechanic which have proved to be a source of much information on the man and his telescopes. He also wrote two chapters in Hutchinson s Splendour of the Heavens, (published in 1923 and edited by his BAA colleagues Steavenson and Phillips) on the subjects of amateur astronomy and astro-navigation.

In the spring of 1903 Ainslie sketched Mars, Saturn and Uranus and in July he had started work on Jupiter too, as well as observing Venus around sunset. All these observations were made while he was fired with the enthusiasm generated by his newly completed 9-inch Newtonian. He also sketched the great naked eye sunspot of 1903 October 13. Two of his observations of Mars from 1903 April 10 and 19 were reproduced in the English Mechanic (2) (see Figure 2a) and Ainslie even compared the first to a sketch of April 5 in the same magazine by the great E. M. Antoniadi (1870-1944). Ainslie used his 9-inch reflector at powers of x200, x270 and x320 for observing Mars that April, but he also added that 'Syrtis Major and snowcap were plain with x100 on aperture 3 1/2-inch during the lunar eclipse.' This was an almost total (97%) lunar eclipse which peaked just after midnight on the night of 1903 April 11/12. Ainslie also mentioned his observations of Venus that summer in the English Mechanic, (3) stating that he could use 500x at 7:30pm on June 28 but could detect no markings.

For those 21st century readers not familiar with the English Mechanic publication, it was a weekly 'newspaper' which ran from 1865 to 1926. However, rather than report news it was crammed with handy articles and letters about science and engineering topics by its readers, many of whom were amateur astronomers. As the articles and letters soon completely dominated the much-loved magazine the contributors declared the English Mechanic as 'Ours'. In many ways it read like an internet forum, except with a space of a week between replies!


The poor weather in October 1903 seemed to attract a few comments in the English Mechanic but Ainslie reported in that same publication that he had been 'more fortunate than Mr Holmes having had two good nights and one very good one', (4) and one of his sketches of Jupiter appeared in the magazine (see Figure 3). The Mr Holmes referred to was Edwin Holmes (1842-1919), discoverer of the first outburst of comet 17P/Holmes some eleven years earlier. During this period Ainslie lists his own address as 'The Chalet, Kingswear, S. Devon', which was a stone's throw from the Royal Naval College at Dartmouth. However, being in the Navy he was frequently based abroad, more often than not in the Mediterranean.

Ainslie's most prolific contribution period to the English Mechanic coincided with the completion of his 9-inch reflector and a total of 57 articles and notes on astronomical themes by him appear between 1903 and 1909. He also contributed many additional notes on microscopy and navigational astronomy. He seems to have been a reader of the magazine from 1902, as two decades later he placed an advert in EM selling all his old copies dating from that year. His most prolific years of contributing to that fascinating magazine were 1903 through to 1906, and most of his astronomical entries concerned mirror making, mirror testing and the benefits of Newtonian reflectors. For example, in February 1904 (5) he comments that he agrees with the comments of Mr Holmes with regard to advocating the use of a wooden tube. Ainslie wrote that he had his 61/2-inch reflector in an open iron tube which was more susceptible to the mercy of the atmosphere and air currents with the flat becoming dewed, which apparently never happened with his 9-inch in a wooden tube.

Ainslie did not just observe planets with his new reflector. For example, his logbook entry for 1904 May 2 records: A splendid night, Comet Brooks well seen.

While on May 21 of that same year he recorded a near-grazing lunar occultation of omicron Leonis as follows, again from his logbook: Star first noticed at 9h 10m, travelled straight for the cusp and must have passed within 1" of the edge ... Star just like a globule of mercury on a dull brass ball!

He reported that same observation to the English Mechanic (6) where he described how he had been examining the craters Eudoxus and Aristoteles at x300 on the first quarter Moon with the 9-inch reflector and noticed a star close to the southern horn. Switching to x140 he waited to see if an occultation would take place. At the critical point the star appeared so close to the lunar peaks that it seemed projected onto them or even to be in front of them! He speculated that if he had been 50 or 100 yards further north he might have witnessed an 'intermittent occultation' from his position of (approximately) 50[degrees] 20' 50"N, 3[degrees] 34' W.

In the year 1905 alone Ainslie submitted an impressive 33 notes or letters on astronomical themes to the English Mechanic, including a ten part description of his 9-inch Newtonian (see Figure 4) entitled 'A Cheap nine-inch reflector' between January and July of that year. (7-16) In the re-submitted sixth (May 1905) instalment of his ten part article Ainslie reveals that his naval career did not stop him contributing the articles, but could be a problem, especially as the seventh article in his series had already been published ahead of sequence due to the original sixth article going astray:

I must begin this by apologizing to readers of 'Ours'for the delay in the appearance of my letter. I am, at this moment, in Marmarice Harbour--one of the finest natural harbours in the world, and one of the most beautiful spots in the Mediterranean; but it is five days' post from England, so that my copy of the 'E.M.' is somewhat belated. My letter VI appears to have gone adrift on the voyage from Gibraltar to England--and as I refer to it in letter VII (344, p. 245, No. 2091), I had better make up the deficiency.

In the final instalment detailing the altazimuth mount and slow motions (see Figure 5, published on 1905 July 28) he makes the comment: Not having any workshop, I was unable to do the work myself, and had to rely on the ability and intelligence of the local blacksmith and carpenter.



While Ainslie was very knowledgeable on telescope design and construction it appears he delegated and paid for the actual mechanical work on his reflector.

Ainslie rarely avoided commenting when telescopes or mirrors were discussed in that year's magazine. For example, in 1905 June, he voiced his suspicions about the alleged high quality of telescope mirrors being made by a Mr Wassell (17) as claimed by other correspondents to the English Mechanic. In the early 1900s the Newtonian reflector was not always viewed kindly by those with the money to afford decent aperture refractors, but any suggestion of refractor snobbery was always pounced on by Ainslie, who frequently defended the 'cheap telescope', stating in one issue (18) that the 'silvered glass Newtonian is now in use at Greenwich and elsewhere for photographs', as proof that a mirror was every bit as good as an object glass.

By 1906 Ainslie's name was surely known by all of the top British amateur astronomers and telescope makers who discussed ideas in the English Mechanic, most of whom were already BAA members. Inevitably, Ainslie was elected to membership of the BAA himself on 1906 May 23 at the age of 36, twelve years into his naval instructor career. Of course, in 1906 May the BAA was a very young association and had not yet celebrated its sixteenth anniversary. By comparison the English Mechanic had been going strong for 41 years. The 1910 return of comet Halley was still four years away when Ainslie joined the BAA, and it was less than three years since the Wright brothers' first powered flight and only four years since Marconi's first transatlantic wireless transmission, something which greatly interested him.

The first mention of Ainslie in the BAA Journal is in the minutes of the 1908 November 25 meeting at the permanent BAA venue of Sion College on London's Victoria Embankment. (19) Ainslie, at 39, was hardly a young member at that meeting, but he would, in the years to come, rise from relative BAA obscurity to become one of its most regular observers and motivating voices. In 1908 Ainslie listed a new address for correspondence at Broadstone in Dorset, but by the start of the Great War he would have moved to London and so would be able to attend most meetings.

There was much discussion at that November 25 BAA meeting about the bright comet 1908c Morehouse and its appearance in photographs, displayed at the meeting by Mr P. J. Melotte (1880-1961). Between questions fielded by W. T. Lynn (1835-1911) and Walter Goodacre (1856-1938), Ainslie (recorded in the minutes as Mr M. A. Ainslie) made his first BAA contribution, commenting that the photographs of comet Morehouse looked like it was making its way through a retarding medium. He added that the envelopes in front of the cometary nucleus struck him as having an extraordinary resemblance to the waves formed in front of the bows of a ship at high speed.

Between 1908 and 1914 Ainslie is not recorded as participating in any BAA meetings or making any contributions to the Journal. Of course, he may simply have been too busy with his career, his family life (there were four children) or he may have been a silent member of the audience, although silence does not seem to have been Ainslie's style at all! Most likely, London was just too far for him to travel on a regular basis.

BAA meetings seem to have been dominated by military men and members of the clergy in the early 1900s and in the years leading up to the start of the Great War another naval Captain, Alfred Carpenter, was a regular contributor at those meetings. Carpenter was an experienced observer of the 'green flash', that is, the flash of green seen when the final part of the solar disk sets below the horizon. The phenomenon is best seen when the horizon is perfectly flat, such as when on a boat looking out to sea. Carpenter published a number of green flash reports in the BAA Journal (20) in the early 1900s and when he addressed a meeting of the Association on 1914 January 28 at Sion College, the President, Colonel E. E. Markwick (1853-1925), asked the audience whether anyone could throw any light on the pink coloured 'stratum' seen by Captain Carpenter above the dawn at sunrise. In reply, although not specifically answering that question, Captain Ainslie, in his second recorded attendance at a BAA meeting, explained that remarkable results had recently been obtained, chiefly by American officers, in measuring the varying dip of the horizon. (21) The officers had used a modified sextant which gave a simultaneous view of the horizon in front of and behind the observer, and Ainslie also emphasised the importance of the observer's height above the surface when observing the green flash. Being a naval Captain, and possessing a fascination with optics and astronomy, Ainslie must surely have seen the phenomenon many times and he described to that 1914 Jan 28 audience how he had once seen the green flash twice on the same evening from HMS Roxburgh in the Bay of Biscay, because the ship was rolling heavily and the quarterdeck's height above the sea was varying rapidly.

Perhaps surprisingly, being a military man, Ainslie seemed able not only to observe more but also to attend more BAA meetings during the First World War period. However, as he was a naval instructor one can speculate that his services were in demand in the classroom, rather than on the seas posing as a target for the German navy. Also, as he was now based at the Royal Naval College at Greenwich he did not have far to travel to the BAA meetings on the Embankment. His postal address during the war years and until the mid-1920s was 69 Shooters Hill Road, Blackheath.

Ainslie was noted as a contributor at the Sion College meetings of 1915 February 24, (22) June 30 and November 24. (23,24) He is also recorded as commenting on the feasibility of observing stars in daylight at the BAA meeting of 1916 March 29.25 At the 1915 February 24 meeting he commented on telescope light grasp and at the latter two 1915 meetings he remarked on the apparent transparency of Saturn's rings, in reply to a paper delivered by the Saturn Section Director Patrick Hepburn (1873-1929). The ring transparency was something Ainslie would actually be able to test, dramatically, two years later.

The transparency of Saturn's rings seems to have been a source of considerable friction between Ainslie and Hepburn over a long period, as we shall see shortly, and the two military men would both serve as BAA Presidents in future years. Hepburn became a Major in the Royal Naval Air Service during that First World War period but was, essentially, a solicitor in the City of London. He may have been the first man to comment on the visibility of Saturn's globe through ring A as recorded in a 1911 photograph by E. E. Barnard. (26) Apart from a two year absence in the War Hepburn was Saturn Section Director from 1912 until his untimely death in 1929.

A 72-inch reflector or not?

Most BAA members will be aware of the giant 72-inch (1.83m) reflector built by the third Earl of Rosse at Birr Castle in Ireland, completed in 1845 and dismantled after the death of the fourth Earl in 1908. In response to a paper by the young W. H. Steavenson entitled 'Note on low powers' published on page 302 of the 1916 June Journal, Ainslie wrote a fascinating reply (27) detailing his own research into the low power 'original' eyepiece used by Lord Rosse's 'great 6-ft reflector', the optical parts of which had (in 1916) recently been moved to the Science Museum in South Kensington and so were easily accessible to Ainslie. Assisted by Steavenson and a Mr Baxendall of the Science Museum, Ainslie was able to measure the 'enormous' eyepiece used with the 6-ft reflector and he and Steavenson agreed (by independent measurement) that the eyepiece had a focal length of 7.7 inches (196mm). Ainslie deduced, assuming a focal length for the giant speculum of 54 feet (16.5m), that the eyepiece magnification would have been 84x. To quote Ainslie directly: 'The diameter of the emergent pencil, or 'Ramsden disc', would therefore be 0.855 of an inch (22mm), much too large to be admitted in its entirety into any human eye, so that under no circumstance could the whole aperture of the speculum have been utilised with this particular eyepiece.'

Ainslie went on to say that if one took Steavenson's value of 0.33 inch (8.4mm) as the diameter of the human pupil in complete darkness, the 72-inch telescope of Lord Rosse would, through the supplied eyepiece, work as if it were actually a 25.2-inch (640mm) reflector with a 9-inch secondary mirror. After taking all transmission factors into account Ainslie deduced that the telescope would, with this low power eyepiece, have the same performance as a 20-inch (508mm) refractor. However, Ainslie did add that he understood powers up to 1000x were employed with the instrument and that with a pupil size of 0.33 inches, a magnification of 216x would indeed be sufficient to utilise the full aperture of the giant telescope.

The BAA meeting minutes for 1916 and 1917 record further contributions by Ainslie. At the meeting of 1916 October 25 he likened the helical path of a meteor, described by Steavenson, to that of a spinning projectile fired from a gun. (28) One month later, at the 1916 November 29 meeting he was full of praise for Captain Carpenter and his son Commander Carpenter. The Captain had described some new astro-navigation rising and setting diagrams, devised by his son, which had been adopted by the Admiralty. (29)

At the meeting of 1917 January 3130 the Jupiter Section Director, the Revd T. E. R. Phillips (1868-1942) showed some photographs of Jupiter taken by Mr John H. Reynolds (1874-1949) with a remarkably large 28-inch (0.71m) equatorially mounted reflector at Reynolds' observatory near Birmingham in October and November 1915. Phillips described the photographs as 'really wonderful,' and thought the exposure times were around two to three seconds in duration. The minutes recorded that: Naval Instructor M. A. Ainslie said that he was much struck by the way in which the curvature of the belts came out in the photographs. Ainslie was referring to the apparent curvature caused by the giant planet's axial tilt. Ainslie also added that he had been observing Jupiter on 1917 January 10 at 4:30pm withthe 10-inch (254mm) refractor at Four Marks observatory and was struck by the great brilliance of what he assumed was the white spot at the following end of the South Tropical Disturbance. After his return from Four Marks he had remarked to other observers of Jupiter that it was 'so bright that it might have been a satellite'. Of course, on reference to the Nautical Almanac, he found that was exactly what it was! [N.B. The author checked this observation out and the satellite was Europa].

The private observatory used by Ainslie, at Four Marks near Winchester, was owned by J. H. Worthington who, in 1914, had offered its facilities to BAA members. (31) These included a 10-inch Cooke refractor (later used by Walter Goodacre and now situated at the Mills Observatory, Dundee) and a 20-inch (508mm) reflector made by Calver. The 10-inch refractor had been purchased, secondhand, by Worthington in 1912 from Baker's of Holborn, London. BAA members Ainslie, Steavenson, Waterfield and J. E. Maxwell (who was killed during World War I) all used the excellent facilities at Four Marks (32) and Steavenson, who observed the equatorial band of Uranus with the instrument in 1915, even compared its usefulness to that of the 28-inch refractor at Greenwich.


At that same 1917 January meeting (33) Walter Maunder (1851-1928) showed a lantern slide prepared by Mr Melotte showing the recent stream of spots on the solar disk, as photographed from Greenwich on January 4. On the same day the observatory had recorded a magnetic disturbance and an aurora. Ainslie commented that two days later, on January 6, he had viewed the great sunspot, again using the 10-inch refractor at Four Marks observatory, and it was 'almost the most wonderful thing he had seenHe was able to use a power of 200, and 'the combination of a perfect object-glass with well-nigh perfect seeing resulted in an absolutely marvellous display of detail'. Ainslie added that he ' almost thought he was looking at the well-known and beautiful drawing of Langley's--A Typical Sunspot.'

The second surviving observing log of Ainslie, also in the possession of David Strange, covers the Great War years of 1917 and 1918 and contains references to air raids and even Zeppelins crashing in flames while observations of the planet Jupiter were being undertaken with his 9-inch reflector. Jupiter was certainly Ainslie's favourite target and his contribution to the BAA's Jupiter Section was substantial even if his drawings were not works of art. To again quote Steavenson from his obituary of Ainslie in the 1951 DecemberJournal: 'He had an accurate eye, and although he made no pretence of being a finished draughtsman, his work was always sound and trustworthy. In particular his systematic observations of Jupiter, his favourite planet, formed a substantial and valued contribution to the work of the Section concerned.'

The famous 1917 occultation

Ainslie's most significant single astronomical observation was made in 1917. On February 9 of that year Ainslie and, independently, J. Knight, observed the magnitude 7 star BD +21[degrees]1714 as it passed behind the A ring and Cassini division of Saturn. (34-36) (The modern designations for this star are GSC 13751267 and HIP 38601). The brightening of the star as it crossed the gap of the Cassini Division was proof that it really was a proper gap and not simply less reflective material. In these days of planetary space probes and webcam imaging such a result may seem trivial, but in 1917 it was very significant. The observation also gave a feeling for just how transparent or how opaque (depending on your viewpoint) the A ring material actually was, a favourite subject of Major Hepburn who, from 1917 to 1919, was temporarily absent as Saturn Section Director and, much to his frustration, did not see the occultation. The caretaker Director during those two years was none other than W. H. Steavenson.

A complete description by Ainslie of the stellar occultation by Saturn's rings was published by the RAS (see Figure 6a) and by the BAA, and Ainslie gave an account of his remarkable observation at the 1917 March 28 BAA meeting. At the time Saturn was very well placed, lying just 7[degrees] below Pollux, in Gemini, transiting at around 22:30 UT at an altitude of almost 60[degrees]. Twelve hours needs to be added to Ainslie's times to correspond with modern UT, a historical timing quirk explained later in this paper. Ainslie used his '9-inch silvered reflector' and employed powers of x180 and x270 throughout the observation. Part of Ainslie's RAS account, dated as being written up on 1917 March 6, from his Blackheath address, is reproduced below. The letters in square parentheses refer to the positions in Figure 6b.

1917 Feb. 9, at about [8.sup.h] [45.sup.m] G.M.T. [A], I noticed a star of about the 7th magnitude north of, and preceding, the N. pole of Saturn. It was of a golden-yellow colour

Circumstances prevented further observation until after 10 p.m. [B], when the planet was again observed, but in poor seeing. It was not until about 10.15[C] that the star was again seen, when it appeared as a very conspicuous cream-white spot, very small, and apparently projected on the extreme edge of ring B; it passed into the division and travelled along it, remaining very conspicuous and, as nearly as I could judge, as bright as when clear of the planet. It does not appear to have passed behind any portion of ring B, as its brightness was so little affected; the appearance of its being projected on the ring was probably an effect of irradiation, the B ring being at its outer edge very bright.


At about 10.30[D] it was seen on the outer edge of the division, and (owing to bad seeing) disappeared for a few minutes; at about [10.sup.h] [35.sup.m][E], however, it was very easily seen, though greatly reduced in brightness, through ring A. It remained visible to the end of the observation and traversed the ring with little or no variation in brightness, though at [11.sup.h] [8.sup.m] it increased very rapidly, not quite instantaneously, to perhaps double intensity, at which it remained from 10 to 15 seconds, fading again as rapidly as it had brightened. A second brightening was observed at [11.sup.h] [8.sup.m][F], this time for not more than about 5 seconds.

The star finally appeared from behind ring A at [11.sup.h] [10.sup.m] [Not labelled by MPM to avoid clutter], and was seen separated from the ring by a distinct black interval at [11.sup.h] [15.sup.m][G]. During the passage of the ring over the star, and when seen through the Cassini division, the yellow colour of the star was much less pronounced than when clear of the planet before and after the observation; it was more in the nature of a creamy white. The image was very 'stellar', especially when seen through the Cassini division; there may have been a very slight enlargement of the image when seen through the ring. I should estimate that the star lost perhaps three-quarters of its light when seen through the ring, but any estimate of the brightness of the star was difficult on account of the glare of the planet. During the brief 'brightenings' in ring A, the star did not attain to anything like its normal brilliancy. The seeing was poor at first, but improved considerably: for a few minutes at about [10.sup.h] [20.sup.m] and again from about [10.sup.h] [35.sup.m] to [11.sup.h] [15.sup.m], the seeing was good, and the image of the star small and round.

A 9-inch silvered reflector was used in the observation, powers 180 and 270.

The alteration in brightness of the star on the two occasions described above, behind Ring A, was very rapid, but not instantaneous; I should estimate that it occupied about half a second, and that the final brightening when clearing the ring took about the same time. It was certainly nothing like the disappearance and reappearance of a star in the case of an ordinary lunar occultation. The times given above for the two brightenings in Ring A, and for the final reappearance are, I believe, correct to the nearest minute.

The apparent position of the star for 1917 Feb. 9d 10h G.M.T. was: [7.sup.h] [49.sup.m] [23.163.sup.s], + 21[degrees] 19' 15".43.

Ainslie also referred to the observations of J. Knight of Rye in his RAS report, noting that the latter observer had not lost sight of the star behind the ball of the planet as it glanced the edge of the globe when seen at x180 with Knight's smaller instrument, a 5-inch (127mm) refractor. Ainslie was of the opinion that Knight's observations were made in poorer seeing conditions than when he observed. In conclusion, Ainslie decided that he could confidently state, from his observations and those of Knight, that the magnitude 7 star was visible through the A ring and had been seen passing through both the Encke division and a division beyond Encke (these correspond to the two brightenings at 11h 8m GMT.) He also concluded that the star did not pass behind Saturn, although it did come extremely close and that the diameter of Saturn's rings in the Nautical Almanac was 'somewhat too small'.

A new Section is formed

In the 1917 May Journal Ainslie wrote a useful three page paper (37) entitled: Notes from the Instrument Committee--On the Choice of a Telescope in which he explained the relative advantages and disadvantages of reflectors, refractors, equatorial mounts and altazimuth mounts. Much of it contained very similar advice to that which he had already written in the English Mechanic, some twelve years earlier. He also warned purchasers to be wary of refractors with stopped down lenses and telescopes mounted on the infamous and very unstable 'pillar and claw' stands. Following this note, in June, only four months after Ainslie's famous Saturn observation, he seems to have convinced the BAA Council to create the 'Methods of Observation' Section and he would serve as its first Director, only being succeeded in the role by Steavenson himself, some fifteen years later. Ainslie announced the formation of the Section at the June 27 meeting. (38) It is worth mentioning that Ainslie, like Horace Dall a generation later, was highly knowledgeable on the subject of both telescope and microscope optics and became the President of the Photo-micrographic Society three years later, in 1920, as well as serving on the council of the Royal Microscopical Society. The 'Methods of Observation' Section kept its name until 1952 and, after several name changes and a merger with the Astrophotography Section, it still survives today as the 'Instruments and Imaging' Section.

The 28-inch, and 10 hours on Jupiter

In the spring of 1918 Ainslie, Revd T. E. R. Phillips and W. H. Steavenson were invited (as described in Ainslie's log book) by the Astronomer Royal, Frank Dyson (1868-1939) to use the 28-inch (0.71m) refractor of the Royal Observatory, Greenwich. Ainslie, Phillips and Dyson were all of the same generation, being aged 48 to 50 at the time, whereas Steavenson, despite his growing reputation, would have been a mere 24 years of age. Across the channel at this time the First World War raged and in late March of 1918 the battle front moved to within 120km of Paris. But the spring of 1918 marked a turning point in the War, with the German army losing the initiative by the summer. The contrast between the three observers serenely studying Mars and the bloodshed in the trenches occurring at the same time could hardly have been more extreme. In 1918 the 28-inch refractor was a mere 25 years old, having been completed in 1893 as a replacement for the 12%-inch (324mm) Merz refractor that originally filled its Greenwich role.

Ainslie's observing book records an observation of Mars made with the giant refractor on May 9, some two months after opposition:

28" O.G.. A clear evening but seeing poor-power 450x: Polar cap very bright with detached patch following. Trivium Charontis very broad. 10.25pm, seeing is vile.


An interesting comment by the young Steavenson on observing with the 28-inch refractor from two weeks earlier (1918 April 22, just four days before his 24th birthday) is also recorded:

I saw very little more than I have seen with a 10-inch O.G. before, but what I saw was seen at once instead of being built up laboriously by an hours steady gazing.

Seven months after Ainslie's view of Mars with the 28-inch and just seven weeks after the World War I armistice of November 11, the Skipper recorded an entire rotation of Jupiter on the night of December 29 GMT from 07h15m to 18h00m GMT. (39) It should be stressed again here that, confusingly, prior to 1925, GMT was reckoned for astronomical purposes from Greenwich mean noon (12h UT) to avoid a date change in the middle of the night in Europe; so a new GMT date started 12 hours after the start of the corresponding civil date. This historical form of timekeeping is nowadays often called Greenwich Mean Astronomical Time (GMAT). So Ainslie's 1918 December 29 observation was actually December 29/30 from 19:15 UT to 06:00 UT. Of course, observing Jupiter from the UK for an entire rotation can only be achieved when the planet is at a high declination and at opposition. At this time the planet satified both criteria, transiting at midnight in Gemini at a declinationjust under +23[degrees].

In the heyday of the visual observer the recording of an entire ten hour rotation of Jupiter in one night was a test of stamina, but one which resulted in considerable kudos for the individual. It was almost a rite of passage to qualify as a member of the planetary observing elite. On this night Ainslie employed his 9-inch silvered reflector, on an altazimuth stand, up to one hour past local midnight (x180, x270 and x400) and then used an equatorially mounted 81/2-inch (216mm) reflector by Calver (x170 and x250) which he seemed to possess at that time. Ainslie's descriptions of Jupiter on that night ran to three pages of the BAA Journal and a strip map of the whole planet was also produced (see Figure 7). Apart from the observation of Jupiter itself he makes the following sage comments:

Long-continued observations of a single object, extending in the present instance to more than 10 hours, are apt to be extremely tiring, and although such a thing is worth doing once, I do not think that much is really to be gained. Towards the end of the observations my eyes undoubtedly began to show signs of fatigue, and I do not think the times of transits obtained during the last hour or two are of anything like the same value as those obtained between 9h and 13h, when the seeing was at its best and my eyes in good condition. In addition to this, I think that one's perception of faint detail is apt to be rather imaginative when the eye is tired.

Towards the end of 1920, Ainslie and Steavenson, in addition to BAA President Major P. H. Hepburn (1873-1929) and a very youthful R. L. (Reggie) Waterfield (1900-1986) who hadjoined the BAA six years earlier, aged 14, were once again invited by the Astronomer Royal to use the 28-inch refractor at Greenwich. (40) It is interesting to note that all these men had been, or would serve as, BAA Presidents at some time in their lives and the same applies to the Revd T. E. R Phillips who had joined the Greenwich group in 1918. In the post-First World War era Hepburn was often granted permission by Dyson to use the giant refractor on Sunday nights.

This time the target for the BAA observers was Saturn, which, according to the elements of H. Struve, would present its rings edge on to the Earth on 1920 November 7d 5h GMT, after which date the un-illuminated ring face would be presented to the Earth. Once again, one has to bear in mind the pre-1925 convention that GMT (GMAT) starts at noon, so, for example, a 1920 November 6 observation at 17:00 GMT means November 7 at 05:00 UT. The original times as recorded have not been altered in the text below. The group of four BAA colleagues managed to observe on five mornings from November 6 to November 20 GMT with Ainslie making the observations on November 7, November 13 (with young Waterfield) and November 20 (with Hepburn). On the other two nights Steavenson made the observations with Hepburn on November 6 and he made all the observations on November 16. On every occasion the magnification used with the giant refractor was x450.

On the first morning of observation Steavenson and Hepburn noted Saturn's edge-on ring as conspicuous, despite only having a ten minute window of clear sky (November 6; 17:00-17:10 GMT) only twelve hours before Earth passed through the ring plane. On the next morning, November 7, from 16:30 to 18:00 GMT, Ainslie described the seeing as 'pretty good, occasionally very good' but 'Not the slightest trace of ring seen', around twelve hours after the rings were predicted to be precisely edge on. However, Ainslie did note that the shadow of the ring on the planet was 'well defined' and 'In the centre the breadth of the shadow was estimated as being about twice the thickness of a micrometer wire, or perhaps a little less'. Ainslie also noted 'a marked difference of colour between the northern and southern hemispheres, the former being bluish green, the latter yellow brown.' Thus Ainslie arguably made the most critical observation of Saturn with the 28-inch refractor with the rings invisible just after the precise time they were edge on to the Earth.

Six days later, on November 13, Ainslie and Waterfield observed from 16:00 to 18:00 GMT, in hazy conditions and with poor seeing. Although the young Reggie Waterfield suspected the merest hint of a ring, near the limb, in poor seeing, it had disappeared in better seeing, and with Ainslie seeing 'no trace of a ring' the two men concluded 'the ring was wholly invisible' six and a half days after the edge-on ring plane crossing. On November 16, observing from 14:30 to 18:00 GMT, Steavenson glimpsed the ring from 15:30 to 16:00 and then held it steady from 16:00 to 18:00 in the giant refractor, describing its 'unequally bright' appearance and noting that 'The whole ring was a most delicate object, and was certainly much more difficult to see than Enceladus'. The final Greenwich observations by members of the quartet were made on November 20 when Ainslie and Hepburn viewed the planet from 17:20 to 19:03 GMT. Both observers saw the ring as clearly visible on each side of the planet.

Time signals, telescopes and a total solar eclipse

At the 1921 February Ordinary Meeting of the Association Ainslie was responsible for halting the eminent Professor Henry Norris Russell (1877-1957) of Princeton University while he was addressing the members! (41,42) Russell's visit to London had already resulted in the BAA cancelling its planned 'Conversation Meeting' that month so the learned Professor could address the members. The temporary adjournment of Russell's lecture was due to an event of some significance arranged between Ainslie and General Ferrie in Paris. Wireless time signals were sent from the Eiffel Tower and received by Ainslie at the meeting, beginning at 5:55pm and continuing for 15 minutes. Ainslie had always taken a practical interest in radio communication, even before the first World War, and spent much time on cloudy evenings in the construction of crystal and valve radio sets. As well as his astronomy and microscopy work he was, for a time, a member of the Council of the Radio Society of Great Britain. Establishing precise astronomical time and synchronising clocks to the 'new-fangled' time signals was of great interest to BAA members of that era and Frank Hope-Jones, the inventor of the Greenwich pips and the electric synchronome pendulum was well known to them.


The President for the 1920-1922 sessions was Ainslie's colleague and occasional adversary the Saturn Section Director Major Patrick Hepburn, and he does not appear to have been ecstatic about a new term which Ainslie was responsible for introducing into the Jupiter observer's dictionary. Ainslie had introduced the naval term 'barges' to describe the elongated dark markings on the North Tropical Zone of the planet, and the Revd T. E. R. Phillips used the term at the 1922 June meeting of the Association while giving an account of a Memoir of the Section. Hepburn commented that he 'could not congratulate Ainslie or Phillips on the introduction of canal language into Jupiter!'43 1922 was the year that Ainslie took early retirement from the Navy and in July 1923 he placed an advert in the English Mechanic stating:

'English Mechanic,' 1902 to 1922, unbound; 'Times History of the War,' complete, first 10 volumes bound, rest unbound; 'Knowledge,' many old copies, unbound; large quantity of 'Monthly Notices of the R.A.S.,' 'Observatory,' and other scientific periodicals.--M. A. AINSLIE, 69, Shooters Hill Road, Blackheath.

Of course, there was no need for Ainslie to live next door to the Royal Naval College at Greenwich any more and so he was probably getting rid of surplus possessions prior to moving to Cocking, near Midhurst in Sussex, where he was based for the next ten years or so, before finally moving to Bournemouth. Certainly, Ainslie's attendances at BAA meetings in the early 1920s seem to have been rather rare.

There seems to have been further disagreement between Hepburn (see Figure 8) and Ainslie early in 1926 when, at meetings and in the January and February Journals (44-47) the two men again sparred over how much a star was dimmed when it passed behind Saturn's rings. Of course, in 1917, Ainslie had actually witnessed this phenomenon, whereas Hepburn had not, but (as mentioned earlier) the Major had famously noted the globe shining through the rings in a 1911 photograph by Barnard and from that point seemed to have regarded himself as the authority on the subject of the transparency of the rings. The 1925/26 re-emergence of the disagreement seems to have started in late 1925 when Hepburn stated that the light from stars was 'but little diminished' when passing behind Saturn's rings, prompting criticism from Ainslie, a counter-criticism from Hepburn in the 1926 January Journal and almost a full page of further counter-criticism from Ainslie in the 1926 February Journal, as well as two further exchanges between the two men. The main thrust of this squabble seems to be that Ainslie argued that a loss of 75% of the star's light, as seen by himself, could hardly be classed as 'little diminished' even if ring A was obviously partially transparent.

The 1926 November 24 BAA meeting (48) once again saw Ainslie as a major contributor when he read a paper to the members written by the Mercury and Venus Section Director Henry McEwen (1864-1955), entitled 'Telescope Eyepieces'. Despite not being the author of the paper Ainslie fielded many eyepiece questions following the reading. In answer to a question from Mr Frank Sellers (1875-1959), Ainslie replied that he definitely regarded monocentric eyepieces as better than orthoscopic eyepieces for planetary work, and he proceeded to draw the internal construction of the eyepieces on the Sion College blackboard. Later in the meeting (49) Mr B. M. Peek (1891-1965) read his paper on the subject of 'Abnormal Jovian Spots in 1920'. Following Mr Peek's delivery Ainslie admitted he had not observed Jupiter at all in 1920 and his further comments illustrate just how little the observers of the 1920s knew about the planet:

I have sometimes wondered whether the belts and other dark markings may not be in the nature of slag, floating on a molten surface: if this view is correct (and I only mention it with the utmost diffidence) then perhaps we might understand that the spots might be, so to speak, 'reflected' from something solid. But it would then be difficult to understand the rapid extension of the South Tropical Disturbance. If, as we are now told by some, the surface of Jupiter is ice-bound, the rapid motion of the spots is still harder to understand.

Although there were years when Ainslie did not contribute many planetary drawings, such as for Jupiter in 1920, it is difficult to compile a comprehensive list of when he did observe, even with access to some of his surviving notebooks. It needs to be remembered that in the days when planetary drawings were superior to photography, and prior to photocopiers being available, an observer needed to make his sketches twice if one copy was to be preserved for himself and another sent to the BAA Section Director. Whether or not the Director correctly recorded your contribution and copied it or returned it, or even lost it, depended solely on the reliability of the incumbent! As far as Mars is concerned the current BAA Section Director Richard McKim made the following comment via e-mail:

'Captain Ainslie contributed data at most, but not all Mars oppositions from 1917/18 till 1943/44. I have either his actual notes, or copies, for all this period. I have few drawings that are in a finished state. He tended to lend his telescopic rough notes and sketches; as nothing was published of most of this data contributed between 1922 and 1944, Ainslie never got his notes back from Steavenson or Peek or Waterfield. So I have them. By 1937 he obviously lost patience, so his notes for that year were never sent in, but are very nice and are in one of his notebooks, though scruffy. His final drawings were redrawn by Henry Wildey in watercolour during WW2 and approved by Ainslie himself/

Ainslie's contribution to the BAA Mars Section is recorded in a few instances in Richard McKim's definitive BAA dust storm Memoir, such as in an observation from 1926 December (50) where we read: 'Phillips found striking changes on Dec 2/3 when there was still bright cloud in Libya (confirmed by Ainslie), the region being wider and whiter than normal, while Iapigia and Deltoton both looked very pale and obscured ...'

Of course, with the track of a total solar eclipse crossing the British mainland on 1927 June 29, the first since 1724 May 22, the 1920s were an exciting time to be a BAA member. A sunset totality just off the Hebrides had occurred on 1925 Jan 24, just two years earlier, but only across British waters. Few BAA members in the 1920s were wealthy enough to travel the globe purely to see an eclipse, and those that possessed the necessary funds always needed to travel by sea and overland. Nevertheless, the wealthiest BAA individuals had seen eclipses before and Hepburn had travelled abroad to a staggering five eclipses prior to 1927.

The whole question of the 1927 British total solar eclipse experience was fully researched and described by R. A. Marriott in 1999.51 At the BAA meeting of 1927 March 30 the coming eclipse was discussed in much detail and a few of those who had seen eclipses before gave their advice. (52) Ainslie was lucky enough to see the eclipse and his contribution is mentioned in the BAA meeting report for 1927 July 6, (53) exactly one week after the event. It was recorded that while most of the scientific results obtained were photographic or spectroscopic Capt. Maurice A. Ainslie was one of the few to produce drawings of the corona.

At that July 6 meeting Ainslie was the last observer to comment on his observations of the eclipse, just moments before the meeting had to be adjourned at 7pm:

I have no photographs, but I made a rough sketch of the extension of the corona immediately after totality. [This was projected onto a screen at the meeting]. The longest streamer was 1.6 to 1.8 diameters of the Sun in length. The corona was, to my eyes, silvery white, but the prominences seemed to me of a curious and striking colour which I can best describe as 'terra-cotta'. It is very interesting to hear that to those above the clouds they appeared pure white. I was using a telescope of about 11/2 inches aperture, and power about 6 diameters: this gave a very bright image. Where the corona was most extended, the radial structure seemed to give way to parallel rays. The approach of the shadow was most impressive: like a thundercloud coming straight at us and falling on us. To those who were not astronomers it may well have been rather terrifying. There must have been some 'Einstein effect' on the time as I never knew 23 seconds so short; I heard 'eighteen' called before I had really got settled down. I have had a letter from a lady belonging to the Ambleside Training College, who was at Bowland Knott, a few miles to the South-west: she says that there were flocks of birds of all sorts close to her, and although they had been making all sorts of noises before totality, the shadow hushed them completely, and they broke out again immediately afterwards. [At this point Major Hepburn, who had been in a plane with Gerald Merton during totality, asked Captain Ainslie a question about the shadow.] The shadow was first seen due South, then swung round to West, then rose up and fell on us, all in a second or two.

With the excitement of the eclipse now ended Ainslie returned to matters of telescopes and instruments and eight months after the eclipse, at the 1928 March 28 meeting, (54) Mr Sellers read his paper entitled 'A portable Altazimuth mounting', which of course was of great interest to Ainslie. After Sellers' talk the Skipper made the following comments:

When Mr Sellers sent me a description of his mounting, I thought for a few moments that I was up against an old friend, namely, a mounting by Brett, which is described in Chambers' 'Descriptive and Practical Astronomy'. Twenty-five years ago, when I made a 9-inch mirror, I found a mounting of this type a complete failure. But when one understands the difficulties to be overcome, I think that it may be said that Mr Sellers has made a great advance in altazimuth mountings.

However, Ainslie did suggest that when a telescope of '60 or 70 lbs' is involved the weight should be counterbalanced, although Sellers replied that the weight was not a problem with his telescope and mounting. One can only imagine how much Ainslie, and Sellers, would have admired the Dobsonian system!

The Presidency and a tragedy

Steavenson had been the BAA President from 1926 to 1928, covering the period of the total solar eclipse. Even today, over 80 years later, no-one has assumed the Presidency at a younger age: he was only 32 in 1926 October. Two years later, in October 1928, Steavenson handed the Presidency over to the 59 year old Captain Ainslie, his choice as successor.

Ainslie's first act on becoming BAA President was to announce the offer of a gift of 300 [pounds sterling] from Walter Goodacre (1856-1938), the renowned Lunar Section Director for the past 32 years, to form a trust from which awards could be given for distinguished astronomical work by members. This offer developed into the establishment of the Goodacre Medal and Gift, an award consisting of a sum of money and a gold medal, the first of which would be presented by Ainslie to the Revd T. E. R. Phillips in 1930.

At the AGM of 1929 October 30 Ainslie delivered his first Presidential Address on the subject of 'The optical system which we use in our observations'. (55) He stressed that his predecessor, Dr Steavenson, had given an address on the optical system of the human eye in the previous year, but he was going to consider what happened to the light as it passed through the telescope. Following his Address, Dr Steavenson proposed a hearty vote of thanks to the President which was seconded by Major Hepburn in, sadly, almost his final appearance at a BAA meeting.

In the 1929 November Journal a paper by Ainslie (56) set out in some detail what the amateur astronomer should be observing if he or she possessed a telescope of 3 or 4 inches aperture, 3 to 5 inches aperture and 5 to 10 inches or larger.

At the 1930 January meeting (57) Ainslie, as President, would announce to members the tragic and puzzling death of his colleague and occasional adversary, Saturn Section Director Major Patrick Hepburn, apparently after a fall at night in the Lake District on Christmas Day 1929, at the age of 56 (the RAS obituary gives the date as Christmas Eve). Howard L. Kelly, writing in The British Astronomical Association: The First 50 years (page 101) (58) states that Hepburn 'died through an accident in the Lake District' and as Hepburn was well known for undertaking solitary expeditions into mountain country, even on cold winter nights, as well as pushing himself to the absolute physical limit while cycling and swimming, (59) an accident of this type seems almost inevitable.

With all the members who were present at that 1930 January meeting standing in respect, Ainslie said:

We meet together this afternoon under the shadow of a great personal loss. As most of you already know, Major Hepburn, one of our past Presidents, and for many years Director of our Saturn Section, was accidentally drowned on Christmas Day in the Lake District. His death removes from among us not only a distinguished amateur astronomer, but a valued member of our Council, whose great legal knowledge was on many occasions most helpful to us.

Ainslie, Sir Frank Dyson and C. O. Bartrum (1867-1939) gave their own tributes to Hepburn's memory and Ainslie read out a letter of condolence to the BAA from Observatory House, Slough, written by no less a person than Francisca Herschel (1846-1932) the 11th child of Sir John Herschel and a granddaughter of Sir William.

Despite Hepburn's demise no new Saturn Section Director was appointed until Ainslie himself took up the role from 1931 to 1934. (In the BAA First Fifty Years Memoir Vol. 42, part 1, Hepburn's reign as director does not officially end until 1931.)

As with any BAA President, in the second year of office a presidential successor has to be proposed and Ainslie's choice was yet another military man, Major A. E. Levin. Remarkably, Levin lived in the same street in Selsey as future President, Patrick Moore, would live decades later, in a house named 'Elleray' just a few minute's walk from Sir Patrick's future home 'Farthings'. Ainslie visited Major Levin a month before the handover and Ainslie's logbook entry for 1930 September 30 reveals that he observed Mars and Jupiter with Levin's 6-inch (152mm) Cooke refractor only a few hundred yards from where Patrick (then aged seven) would observe in the future. The logbook entry for that September 30 observation records: A very perfect O.G. x196 the best power. Mars--a yellow patch is crossing the polar cap.

At the 1930 October 29 AGM, prior to his second Presidential Address on amateur telescopes, Ainslie had the pleasant duty of presenting the first Goodacre Medal to the Revd T. E. R. Phillips for his outstanding observations of Jupiter, Mars and long period variable stars. (60) In the previous week Ainslie had enjoyed 'the pleasure of observing with the 18-inch (457mm) spec. at Headley' (Phillips' observatory), and he commented that 'It gave me a most magnificent view of the Jovian detail.' To quote precisely from Ainslie: (61)

A very fine view indeed with x260. TERP did not praise the seeing but after Cocking it seemed to be very good (7-8). The large aperture gave splendid illumination and one felt as if one was watching a perfect coloured drawing hanging in front of ones eyes ... Satellite III in occultation showed the phase effect strikingly.

And so, in 1930 October, Ainslie's term as BAA President came to an end and he was able to hand over to Major A. E. Levin of West Street, Selsey.

Telescopes, eyepieces and a trip to South Africa

Free from the duties of the Presidency Ainslie was able to recommence where he had left off, on his favourite topic of instruments and observing methods. Thus, at the 1931 February BAA meeting he gave an account of the design of the Tolles eyepiece, explaining that a member of the Association, none other than Horace Dall of Luton (see Figure 9), had sent him three eyepieces of this design that he had made himself 'and they are so good that I think members should know something about them'. (62) Ainslie explained that even on a reflector 'as fast as f/7' the performance of Dall's Tolles eyepieces was extremely good and their only disadvantages were that the design prohibited the use of a micrometer, and that the eye had to be held very close to the lens. In conclusion he told the members that they should congratulate Mr Dall on his optical skill, and congratulate the Association that the eyepieces were the work of one of its own members. T. E. R. Phillips added that he had tried one of these eyepieces on his 18-inch reflector with excellent results and he too was gratified to find a member of the Association making eyepieces this excellent. Walter Goodacre also confirmed the good opinions of these eyepieces, saying he had tried one on his 10-inch refractor.


At the 1931 May 27 meeting at Sion College, Ainslie exhibited two long-focal-length speculum metal mirrors which Dr Steavenson had informed him were almost certainly made by William Herschel. (63,64) The telescopes were identical, having apertures of 6.3 inches (160mm) and focal lengths of 86 inches (2.18m) making them f/13.7. In the 1931 December Journal Ainslie described his findings when testing them, using a frame he had constructed for use with a 10-inch mirror of similar focal length and a right angle prism supplied by F. J. Hargreaves (1891-1970). Ainslie's first finding was that the metal mirrors distorted far more easily under their own weight than a glass mirror of the same size, but this was solved by providing an 'evenly supporting cloth backing'. On star testing he found both mirrors were identical and produced exquisite images even at x350 and 'near perfect' at x450. As well as testing Herschel's mirrors on double stars, Ainslie also looked at Saturn and Uranus with the mirrors. The Uranus observation was especially appropriate as, of course, the seventh planet was discovered by Herschel. Ainslie determined that the mirror surfaces were almost perfectly spherical, which, at f/13.7, was indistinguishable from parabolic. In concluding Ainslie reported in the Journal that: 'I think we may say then, that at least two of Herschel's smaller specula are fully up to modern standards, and would bear comparison with the best work of any modern artist.'

The 1932 February Journal featured a paper by H. H. Waters in which the author had tested a 51/8-inch (130mm) refractor and a 61/4-inch (159mm) reflector, vastly preferring the refractor and concluding that a 6-inch (152mm) instrument on an equatorial mount with a clock drive was far preferable to a 12-inch (305mm) instrument on a tripod. Just two pages later in the Journal, Ainslie systematically dismantled Waters' paper in a three page lambasting of his findings. (65) In fact, Ainslie's 'note' on Waters' paper was almost double the length of the original! However, on reading both papers it is obvious that Ainslie's criticism was fully justified, as not only was Waters not comparing like for like (the refractor was in a dome and the reflector had a poor mirror), he seemed to be ignoring the great work carried out by observers of the time using altazimuth mounted reflectors.

Ainslie ends his critique on Waters' paper by offering 'a word of advice' to would-be observers: 'go for the largest speculum you can afford to mount, and do not be worried too much about equatorials and clock drives.' He added: 'remember that an astronomical telescope is intended to be looked through, not looked at.' Again, it sounds like Ainslie really would just have loved a big Dobsonian!

At the 1932 July BAA meeting (66) a thirty-one year old Horace Dall (still remembered well by many senior BAA members today), only four years after he built the first Dall-Kirkham Cassegrain, gave a rare presentation to the members at Sion College. Dall was never a confident speaker, indeed he hated public speaking. He was of very small build and very quiet and at many BAA Council meetings he attended he often said very little. But for his quiet nature he would certainly have become a BAA President, but the thought of that role terrified him. The large and loud Ainslie and the small but quiet Dall must have seemed like complete opposites, but they became firm friends and Ainslie visited Horace many times, first at Horace's Dunstable Road address in Luton, before he married, and then at his marital home at 166 Stockingstone Road.

That July, Dall brought to the meeting a 6-inch (152mm) Dall-Kirkham Cassegrain which he had built himself and which, weighing 51/2 lbs (2.5kg), was amazingly compact by the standards of the 1930s. The telescope was principally intended for terrestrial use as its baffle tube incorporated a triple element achromatic transfer lens which gave an erect view. However, Horace preferred an erect view for observing astronomical objects. The primary mirror of the Cassegrain was a very fast f/3.2 (an almost unheard of f-ratio in the 1930s) and the final f-ratio was only 15, much less than other Cassegrains of that era. After Dall finished describing his telescope Ainslie was full of praise for the young Horace and his instrument, stating that at f/15 normal eyepieces could be employed with the instrument. Ainslie suggested that while an erect image for planetary observing might seem like a disadvantage the unusual astronomical orientation it produced might actually help eliminate observer bias when making observations.

At the 1932 December meeting, following a presentation by Mr Robert Barker about Saturn's appearance that year, (67) Captain Ainslie said that it was time observers began to take a more serious interest in the planet, and he believed that southern hemisphere observers were now engaged in such work. With regard to the points raised by Mr Barker concerning the possible eccentricity of the position of the ball of Saturn with respect to the rings, he cautioned that all optical appearances are subject, in some degree, to slight illusion and he did not feel sure that these observations had corresponded to actual physical truth. The President, Dr Alfred Parr (1865-1936), remarked on the interest with which all present must have received Captain Ainslie's comments following Mr Barker's paper, especially as the Captain enjoyed the enviable distinction of being one of the very few observers who had seen a star through the Cassini division. The President was aware of the Captain's impending visit to South Africa and he felt sure that all present would wish him a pleasant sojourn and a safe return.

Ainslie would spend the whole of 1933 away from the UK, including the period of excitement when the comedian Will Hay discovered Saturn's white spot in August of that year. Hay hadjoined the BAA in 1932, only a year earlier. (68) Ainslie was eventually appointed as caretaker Saturn Section Director from 1932 onward, and so as Director was outside the country when news of the white spot broke and attracted the media. Nevertheless, news reached him in South Africa and he was able to observe the spot himself. Ainslie spent a long period in South Africa visiting and staying with one of his daughters who lived in Cape Town.

Upon Ainslie's return to England (69) he was welcomed back by the BAA President (still Dr Alfred Parr) at the 1934 April meeting and described his observing experiences in that distant country where he had transported his 9-inch reflector. He remarked that although the transparency of the South African sky was sometimes extraordinary, as a rule the seeing at the Cape Peninsula, where he had carried out all his observing, was poor. However, he did add that Mr H. E. Wood, the Union Astronomer at Johannesburg, had advised that conditions were much better 'up country'. Mr Wood had a reputation for measuring double stars with the 261/2-inch (0.67m) refractor there. To emphasise how poor he (Ainslie) had found seeing at the Cape he found it sometimes impossible to make out that Saturn had a ring at all, even if a few good views of that planet and Jupiter had been obtained. Ainslie had been allowed access to the 18-inch (457mm) refractor at the Cape (as well as some smaller instruments) by kind permission of Dr Jackson, which had allowed him fair views of Jupiter and a few extremely good views of Saturn. But in a south-easterly breeze, or a 'south-easter' as Ainslie described it, Mars, Jupiter and Venus all twinkled and on one occasion he could not split alpha Centauri despite its six or seven arc-second separation. It had been 'a large, quivering patch of light' in his 9-inch reflector. But Ainslie added that the seeing was liable to alter very rapidly and in the course of half an hour it might become quite good and then deteriorate again.

But it had not all been poor observing at the Cape, as Ainslie explained that the clearness and beauty of the night sky, especially in January, when 'the glorious procession of stars from Capella and Aldeberan, through Orion, Sirius and Canopus down to the Southern Cross and alpha and beta Centauri passed overhead' had impressed him more than anything else, except, perhaps, the Victoria Falls. He added that Omega Centauri, 47 Tucanae, Alpha Crucis and eta Argus were magnificent. Ainslie also added that he was not surprised that South African comet hunters should be so successful given the transparency of their skies. Remarkably, when one considers all of Ainslie's other interests, he even found time during his stay in Cape Town to play the title role in a local performance of Omar Khayyamm!

Shortly after Ainslie's return to England he handed over his caretaker Directorship of the Saturn Section to B. M. Peek. However, Peek would only hold the post for a year, issuing one 'interim report' on Saturnian equatorial disturbances. Peek took over both the Jupiter Section, from Phillips (after 33 years in the role), and the Saturn Section in 1934. But a year later Phillips himself agreed to take on the far less demanding Saturn post for the next four years (1935-1939).

The Jack-Knife refractor

In Ainslie's BAA obituary (1) Steavenson recorded that the Captain's 9-inch reflector had become 'unusable due to the complete decay of its tube and mounting'. This deterioration appears to have become terminal by the mid-1930s, perhaps accelerated by its transportation to South Africa and back. In addition, the Skipper had turned his practical telescope designing skills to assembling a refractor, despite a lifetime spent promoting the advantages of reflectors. Ainslie had acquired, gratis, an 81/2-inch (216mm) f/14 achromatic objective lens (made by Grubb) from the Hon. Lionel Guest. He was not satisfied with the performance of the Grubb lens and so contacted his friend Horace Dall who, despite only being in his mid-30s at the time, was already regarded as an optical genius. Beyond the age of sixty Ainslie had suffered increasingly from arthritis and so this was also an opportunity to make a user-friendly telescope by folding the 10-foot light path and positioning the eyepiece at a comfortable eye height. Ainslie would describe the resulting design as either his 'refracto-reflector', his 'compact reflex mounted refractor' or even his 'catadioptric tube', although in later years Horace invariably called his solution 'The Jack-Knife telescope'. The instrument was described by the Skipper in the BAA Journal. (70)

Judging by a comment thrown into his critique of H. H. Waters' paper in the 1932 February Journal where Ainslie comments 'I have myself had, for several weeks past, an 81/2-inch object glass, mounted on an altazimuth tripod, in regular and effective use on Jupiter', it is obvious that from early 1932 he had experimented with a folded refractor solution following the initial gift of the object glass from Lionel Guest. Indeed, in that same critique Ainslie mentioned that he had been using the tube of his old 9-inch reflector to temporarily house the folded refractor, and the alt-azimuth mounting of the 9-inch instrument too. But as previously mentioned, he was not happy with the system's performance, even after Sir Howard Grubb, Parsons & Co. had 'reannealed and reworked the lens and provided a cast iron cell and tube attachment'. So after his return from South Africa he decided to improve the optics and transfer it to an equatorial mount, while retaining a user-friendly eyepiece position and the wide, flat field of the object glass; hence the involvement of Horace Dall.

In his BAA paper on the folded refractor Ainslie outlined five criteria for the new instrument which, in summary, stated that it should be compact, comfortable for prolonged Jupiter observation, capable of field orientation control, of low cost and transportable. Ainslie considered using folded refractor designs based on what he called the Paris and Cambridge Coude systems, as well as the Paris 'Manent' folded refractor where the final beam exits along the declination axis. In the end he decided to 'adopt a modification of the Manent system, bringing the final beam out near the object glass, and mounting the prism and eyepiece so as to be capable of rotation round the axis of the beam returning from the flat mirror' (see Figure 10). The prism Ainslie mentions was a 11/2-inch unit kindly provided by the BAA's F. J. Hargreaves. The mounting was designed and constructed by Eric W. Perry of Luton, who lived not far from Dall, and who appears with Ainslie in Figure 11.


The instrument seems to have been finally completed to Ainslie's satisfaction in 1936, after which he refers to the aperture as being fractionally smaller, namely 8.4 inches (213mm). Two further views of the Jack-Knife telescope are shown in Figures 12 and 13. No doubt the completed instrument was a subject of conversation at the 1936 April BAA dinner at Frascati's restaurant, where the unmistakeable figure of Ainslie is clearly visible in Figures 14a and 14b.

In passing, it is worth noting that around the period of the Jack-Knife's completion Ainslie was recorded as being present at the Sion College BAA meeting of 1936 November 25, where Will Hay famously showed his cine film of the 1936 June 19 total solar eclipse as well as describing his 'Application of a synchronous motor to a chronograph'. The minutes recorded that following Hay's chronometer presentation there was a discussion on the subject in which Captain Ainslie, Dr Steavenson, Mr F. J. Hargreaves and Dr Haughton took part. (71)

The current owner of the unique Jack-Knife telescope is David Strange. Almost thirty years ago and a half-century after its original construction Horace, then aged 80, described the history of the Jack-Knife Refractor and the Grubb refigured lens in a 1981 letter to David:

The Skipper asked if I would test and refigure it. I found zonal focal errors of 3mm or so, errors on all 4 surfaces which I corrected. When informed of the errors Grubb Parsons said they were within their normal tolerance of 0.1% of the focal length! This was not good enough for us. The Skipper discussed the question of mounting, and folding was proposed to make the mount more manageable. I made a very accurate 6" flat for the folding and did all the work while Eric Perry made the tube and mounting. When finished I had a splendid view of Jupiter through it and it is in fact a first class telescope.

Dall also described the Jack-Knife telescope in a letter to Albert Ingalls in an American publication (72) in 1937 October. Ingalls' comments, after reporting Dall's letter, include the line: Someone nicknamed the 'scope the 'Jack-Knife' telescope and it apparently stuck. Dall's own description of the telescope design in his letter was quoted as:

It's not everybody's luck to possess a first-class astronomical object glass of large aperture, but possession of the O.G. is only part of the battle. The usual focal length is anything from 13 to 17 diameters and the rigid mounting of such a long telescope on a stand tall enough to give comfortable views at the eye end is no light job. Captain M. A. Ainslie of Bournemouth, England, possessed an 81/2" object glass of 10' focus, and having decided that the ordinary long tube mounting was too cumbersome to consider, schemed out a system of folding which better than halves the length and gives far more comfortable viewing even than a standard refractor fitted with a star diagonal. Only one additional reflection is needed, in comparison with the latter, and the final image has the advantage of normal astronomical inversion, while the eye tube can be swung round to suit any chosen angle of view either for comfort or orientation of image. It will be seen that the center of gravity of the system comes fairly near to the eyepiece mount. This adds further to the comfort by reducing the range of movement of the eyepiece. The illustration shows the details of the sturdy portable form of equatorial mounting adopted, with slow motion and circles. A long dew cap is fitted to the O.G. and the whole tube is of wood and covered with zinc for working in the open. Mr Perry (left) of Luton built the entire stand and tube while the optical items and most of the instrument work were by myself. The instrument is now in regular use (mostly on planetary work) by Captain Ainslie who is one of England's most prominent amateur astronomers. He also possesses a reflector of larger aperture (9") made by himself many years ago, and the use of the two instruments side by side entirely confirms the well-recognized fact that a refractor folded or not) gives much steadier images than a reflector, though on comparatively rare occasions the latter shows to advantage.



Ingalls revisited the subject of what he called Ainslie's 'Reflex Euphonium Refractor' a year later in 1938 September. (73) Ingalls refers to Ainslie as being 'well known in British amateur circles because of his work in practical astronomy', citing his chapter 'Astronomy in Navigation' in the book The Splendour of the Heavens. He quotes directly from a letter sent by the Skipper:

It has occurred to me that some further remarks concerning the instrument--which has now been in regular use for two years--might be of some interest to your readers. As shown in your photo, the triangle which forms the base of the mounting stands clear of the ground; this was soon found to cause some inconvenience, as well as to make the eyepiece rather inaccessible in some positions; so the triangle has been sunk 6" in the ground with great advantage. At the greatest northern declination (about 43 degrees north) which permits of the telescope passing the meridian without reversal, the lower end of the tube just swings clear of the ground, while the eyepiece is always readily accessible. In respect of convenience of working the instrument equals, if it does not surpass, a reflector with rotating tube; and the optical parts, once adjusted, are so stable that finding objects by the circles is an easy matter. This is just as well, since it has not, as yet, been found easy to mount the finder so as to be easily accessible in all positions; the arrangement shown in the photo is probably about the best, but is not very satisfactory; however, since the finder is hardly ever used, this does not matter very much. The 'swiveling' arrangement for the eyetube, giving a side-to-side range of some 225 degrees, has been found very advantageous--especially for work on variable stars--as the orientation of the field of view is always under control.

Of course, with two reflections between the object glass and the eyepiece, some loss of light is bound to occur; assuming 87 percent for the reflectivity of the aluminized 6" flat, and the same figure for the prism, the effective aperture of the object glass is about 8.4" x 0.87, or about 7.3"; this gives ample light for such powers as can usefully be employed on Jupiter; while I find that my not very sensitive eye can just see steadily a star of magnitude 13.7 on a good night, so that there is sufficient light for observation of pretty faint variables. [Author's note: Although Ainslie was, primarily, a planetary man he was also a keen observer of variable stars and contributed many estimates to the BAA Variable Star Section].

The circles, which are divided only to half degrees and read by simple pointers, bring any desired object into the field of a low power eyepiece giving x60 and a field of 43'; and the remarkable stability of the whole stand goes a long way toward making 'setting' easy and certain; repeated tests on the Pole Star have failed to show any appreciable movement in the polar axis.

I venture to think that anyone possessing an object glass of similar, or even greater aperture, might do worse than consider the possibilities of this form of mounting, especially for prolonged observation of such an object as a planet.



Once again Ingalls quotes Horace Dall regarding the design of the telescope for comfortable viewing:

The whole point of that extra reflection is accessibility of eyepiece and orientation of image. The Captain is keen on planetary work, in estimating position angles of Jovian spots, and so on. He prefers to set the belts horizontal, which is easily done by swinging the short, projecting eyepiece tube round.

As an almost final note in his BAA paper, Ainslie describes the Jack-Knife telescope as being easily transportable, despite weighing 500lb! The tube plus optical fittings weighed 100lb and the counterweight 75lb. Steavenson's description of Ainslie as being built 'on massive lines' is surely putting it mildly if, even with arthritis, he considers a 500lb telescope easily transportable. Indeed, Ainslie comments that 'I was able to transport the complete instrument from Luton to Bournemouth --125 miles--in a single journey in a not very large car without the slightest inconvenience, and to unpack it and re-erect it single-handed.'


Towards the end of his life the Skipper sold the Jack-Knife refractor to Bill Day who in turn sold it to Dudley Fuller who sold it on to David Strange. Bill Day also handed Ainslie's observing notebooks to David.

At the 1937 May BAA meeting (74) Ainslie projected onto the screen some drawings of Mars made with his 8.4-inch folded refractor during the current apparition, despite the planet's altitude of only 18[degrees] at transit from his Bournemouth site. He had used powers from 190 to 336 but mainly x244. Ainslie said that he had been much struck by the intense blackness of the northern part of the Syrtis Major, the darkness of mare Acidalium, the inconspicuousness of the polar cap and the prevalence of brilliantly white spots or areas on the limb.

After 1937 and throughout the second World War, Ainslie seems to have been pretty much absent from BAA meetings, although he can clearly be seen at the 1938 and 1939 meals at Frascati's restaurant as shown in Figures 15 and 16. But he was still observing in earnest then and a sketch of Jupiter made in 1938 July, using the Jack-Knife telescope, is shown in Figure 17.

Of course, as he reached 70 in 1938 and was known to have worsening arthritis, this may have been the reason for his absence from BAA meetings in the 1940s. In addition, his sole surviving son, serving with the RAF, was lost in action over Germany in the War which must have been a tragic blow. Nevertheless, Ainslie still had a regular presence in the BAA Journal as he was once again the caretaker Saturn Section Director during the period of the second World War (1939-1945), following the resignation of Phillips from that post. Ainslie produced regular, if brief Section reports from 1941 to 1946 (75-80) as well as notes concerning a white spot on Saturn's rings (81) and a dark projecting spot on the planet. (82) However, reading these reports it is obvious that trying to encourage much interest in observing Saturn was an uphill struggle in the 1940s. The combination of the War, the relatively featureless globe compared to Jupiter, and the lack of large apertures in amateur hands all conspired to make observing the ringed planet a thankless task in the years after the excitement of the 1933 Will Hay spot.

Richard McKim has pointed out that the early-morning Jupiter work Ainslie carried out, despite his arthritis, in the first few years of the Second World War was absolutely critical to the continuation of the charts of the Section under B. M. Peek. (83) With reference to the 1941-'42 apparition Peek described Ainslie as a man 'who worked heroically long after midnight and to whom the knowledge of the motions of some spots before opposition is almost entirely due.' Ainslie's logs also show he took down shorthand notes at the eyepiece, especially when doing Jupiter transits.

Towards the end of the second World War, at the 1945 April meeting of the Association, Frank Holborn exhibited some very fine photographs of Saturn originally taken with the 36-inch (0.91m) Lick refractor in 1939 and 1943, and recently donated to the Association by the Lick Observatory Director Dr J. H. Moore. Mr Holborn was able to project these photographs at the May meeting and the editor managed to reproduce them in the 1945 July BAA Journal. (84) At the time these photographs were arguably the best earth-based photographs of the ringed planet and, also in the July Journal, Ainslie commented that they were 'quite the best of Saturn that I have ever seen'. His further comments regarding the Lick photographs are interesting as they illustrate the limited knowledge that the observers of the 1940s had without access to space probe images:


Encke's division in ring A does not seem to be evident, although it was by no means a difficult feature in 1943 with anything larger than 8-inch aperture; Phillips saw it many times, and (I think) Peek, and in good seeing I could see it, I think certainly, with 8%-inch O.G. (Thisrather indicates the limitations of large apertures for planetary photography.)


The brightness of ring A seems considerably greater towards the inner edge, especially in the 1943 photo, though quite perceptible in the 1939 [one]; it is, of course, possible that the photos give the true appearance of this ring and that Encke's division is not the fine line so often drawn; but I seem to remember that some observations were made (I forget by whom) [Author's note: the observations were by Keeler] with the 36-inch towards the end of the last century, in which Encke's division was described as an extremely fine line a little outside the centre of the ring's width. But as Encke's division seems to vary continually in appearance, this really proves nothing as to the true nature of it, but merely that it was seen as a fine line on a particular occasion; and we do not forget that there are some observers who see 'fine lines' everywhere.

Despite Ainslie's efforts to encourage Saturn observations, the Section was almost dead by the end of the War and at the end of 1946, at the age of 78 Ainslie, now in poor health, resigned and a new Director, Dr A. F. o'D. Alexander, took over. Ainslie wrote to Alexander around this time (either in 1946 or '47) saying that the mere task of preparing meals at home and household chores was all that he and his wife could manage during the course of the day. (85)


Ainslie died at Wallisdown, Bournemouth, on 1951 January 19. He had lived in Bournemouth since the mid 1930s and had become Chairman of the Astronomical Section of the Bournemouth Natural Science Society. Ten years earlier he had given a different type of Presidential Address to that Bournemouth Society entitled 'Life on other worlds', and he had also given lectures on behalf of the Oxford University Extension Lectures Committee, and a number of BBC radio broadcasts on astronomy, many in the Children's Hour.

Ainslie bequeathed the mirror of the nine-inch telescope to the BAA (instrument number 149). It was listed as being 'available' in the Journal in 1985 and 1990 but has since gone missing. Ainslie was survived by his wife and two daughters, but outlived his two sons, one of whom died in childhood and the other (as we saw earlier) was lost in action with the RAF over Germany during the Second World War.


A number of people have helped me trawl in useful data for this paper and I am grateful to Peter Hingley, Eric Hutton, Richard McKim and David Strange. I am especially indebted to Richard for supplying the 1930s BAA Dinner pictures and helping me to identify who is present in them, as well as supplying a good quality BAA portrait of Ainslie. I am also grateful to Robin Scagell for lending me his video of Horace Dall some twenty years ago, my copy of which contained some useful snippets regarding Ainslie and Hepburn.

Address: Denmara, 5 Oldhall Lane, Cross Green, Cockfield, Bury St Edmunds, Suffolk IP30 0LQ. []


(1) W. H. Steavenson, J. Brit. Astron. Assoc., 62(1), 44 (1951)

(2) M. A. Ainslie, English Mechanic, No. 1988, 255, 1903 May 1

(3) M. A. Ainslie, ibid., No. 1997, 459, 1903 July 3

(4) M. A. Ainslie, ibid., No. 2012, 223, 1903 October 16

(5) M. A. Ainslie, ibid., No. 2030, 35, 1904 February 19

(6) M. A. Ainslie, ibid., No. 2044, 360, 1904 May 27

(7) M. A. Ainslie, ibid., No. 2079, 571, 1905 January 27

(8) M. A. Ainslie, ibid., No. 2080, 596, 1905 February 3

(9) M. A. Ainslie, ibid., No. 2083, 36, 1905 February 24

(10) M. A. Ainslie, ibid., No. 2086, 131, 1905 March 17

(11) M. A. Ainslie, ibid., No. 2087, 154, 1905 March 24

(12) M. A. Ainslie, ibid., No. 2092, 245 and 265, 1905 April 28

(13) M. A. Ainslie, ibid., No. 2095, 337, 1905 May 19

(14) M. A. Ainslie, ibid., No. 2096, 358, 1905 May 26

(15) M. A. Ainslie, ibid., No. 2099, 340, 1905 June 16

(16) M. A. Ainslie, ibid., No. 2105, 567, 1905 July 28

(17) M. A. Ainslie, ibid., No. 2099, 430, 1905 June 16

(18) M. A. Ainslie, ibid., No. 2225, 334, 1907 Nov 15

(19) J. Brit. Astron.. Assoc., 19(2), 74 (1908)

(20) ibid., 24, 216 and also 25, 47; 26, 168; 22, 372; 23, 97

(21) ibid., 24(4), 188 (1914)

(22) ibid., 25(5), 210 (1915)

(23) ibid., 25(8), 364 (1915)

(24) ibid., 26(2), 63 (1915)

(25) ibid., 26(5), 217 (1915)

(26) ibid., 24,479 (1914) and also 25, 386 (1915)

(27) M. A. Ainslie, 'The lowest available Powers of a Telescope: A Note on Mr Steavenson's Paper', J. Brit. Astron. Assoc., 26(8), 303 (1916)

(28) J. Brit. Astron. Assoc., 27(1), 28 (1916)

(29) ibid., 27(2), 64 (1916)

(30) ibid., 27(3), 99 (1917)

(31) J. H. Worthington, ibid., 25, 49 (1914)

(32) R. Moseley, ibid., 98(3), 164 (1988). See also H. Ford, 'The Mills Observatory Dundee', ibid., 93(6), 251 (1983)

(33) ibid., 27(3), 101 (1917)

(34) ibid., 27(5), 163 (1917)

(35) M. A. Ainslie, 'Occultation of B.D. +21[degrees], 1714, by Saturn's ring, 1917 Feb. 9', J. Brit. Astron. Assoc., 27(7), 212 (1917)

(36) M. A. Ainslie, 'Occultation of B.D. +21[degrees], 1714, by Saturn's ring, 1917 Feb. 9', MNRAS, Vol. 77, p.456

(37) M. A. Ainslie, 'On the choice of a telescope', J. Brit. Astron. Assoc., 27(7), 232 (1917)

(38) ibid., 27(8), 250 (1917)

(39) M. A. Ainslie, 'Observations of a complete rotation of Jupiter', ibid., 29(4), 103 (1919)

(40) P. H. Hepburn et al., 'Observations of Saturn 1920 November 6 to November 20', MNRAS Vol. 81, p.126

(41) J. Brit. Astron. Assoc., 31, 183 (1921)

(42) H. L. Kelly, 'The British Astronomical Association: The first 50 years', Mem. Brit. Astron. Assoc., 42, Part 1, p.30 (1989)

(43) ibid, p.33

(44) P. H. Hepburn, 'Constitution of Saturn's rings', J. Brit. Astron. Assoc., 36(4), 120 (1926)

(45) M. A. Ainslie, 'Loss of light through Saturn's rings', ibid., 36(5), 156 (1926)

(46) P. H. Hepburn, ibid, p.198

(47) M. A. Ainslie, ibid, p 261

(48) ibid., 37(2), 50 (1926)

(49) ibid., p.54

(50) R. J. McKim, 'Telescopic martian dust storms: a narrative and catalogue', Mem. Brit. Astron. Assoc., 44, p.50 (1999)

(51) R. A. Marriott, '1927: a British eclipse', J. Brit. Astron. Assoc., 109(3), 117 (1999)

(52) ibid., 37(5), 193 (1927)

(53) ibid., 37(8), 301 (1927)

(54) ibid., 38(6), 168 (1928)

(55) ibid., 40(1), 5 (1929)

(56) M. A. Ainslie, 'Methods of Observation, work for the amateur observer. 'What shall I observe?' J. Brit. Astron. Assoc., 40(1), 43 (1929)

(57) ibid., 40(3), 97 (1930)

(58) H. L. Kelly, op. cit. (ref. 24), p. 101

(59) J. Brit. Astron. Assoc., 40(5), 166 (1930)

(60) ibid., 41(1), 4 (1930)

(61) Transcribed from Ainslie's log book passed from Bill Day to David Strange.

(62) J. Brit. Astron. Assoc., 41(4), 157 (1931)

(63) ibid., 42(2), 54 (1931)

(64) M. A. Ainslie, 'Note on the performance of two specula by Sir William Herschel', ibid., 42(2), 65 (1931)

(65) M. A. Ainslie, 'Reflectors and refractors, a note on H. H. Waters' paper', ibid., 42(4), 142 (1932)

(66) ibid., 42(9), 319 (1932)

(67) ibid., 43(2), 40 (1932)

(68) M. P. Mobberley & K. J. Goward, 'Will Hay (1888-1949) and his telescopes', J. Brit. Astron. Assoc., 119(2), 67 (2009)

(69) ibid., 44(7), 255 (1934)

(70) M. A. Ainslie, 'A complex 'reflex' mounting for a refractor', ibid., 46(9), 324 (1936)

(71) ibid., 47(2), 58 (1936)

(72) A. G. Ingalls, 'The Amateur Telescope Maker', Scientific American, p.232, 1937 October

(73) A. G. Ingalls, 'A Reflex Euphonium refractor', ibid., 1938 September

(74) J. Brit. Astron. Assoc., 47(8), 288 (1937)

(75) M. A. Ainslie, 'Saturn Section', ibid., 51, 351 (1941)

(76) M. A. Ainslie, 'Saturn Section', ibid., 52, 308 (1942)

(77) M. A. Ainslie, 'Saturn Section', ibid., 53, 85 (1943)

(78) M. A. Ainslie, 'Saturn Section', ibid., 54, 85 (1944)

(79) M. A. Ainslie, 'Saturn Section', ibid., 55, 176 (1945)

(80) M. A. Ainslie, 'Saturn Section', ibid., 56, 156 (1956)

(81) M. A. Ainslie, ibid., 51, 312 (1941)

(82) M. A. Ainslie, ibid., 53, 250 (1943)

(83) B. M. Peek, 'Jupiter Section Memoir', Mem. Brit. Astron. Assoc., 35(3) 1944

(84) M. A. Ainslie, 'Photographs of Saturn by the Lick Observatory Note by the Director of the Saturn Section', J. Brit. Astron. Assoc., 55(5), 125 (1945)

(85) Information supplied by Richard McKim in an e-mail of 2009 April 28.

Received 2009 May 10; accepted 2009 June 24
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