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Ransomes' Astronomical Equipment


During a visit to the Royal Greenwich Observatory (RGO) in early 1998, I noticed the maker's plate on the Airy Transit Instrument bearing the designation Ransomes & May, Engineers, Ipswich. This observation inspired two lines of enquiry:

Before attempting to answer these questions, some historical background will be helpful to establish the context.

Ransomes of Ipswich

In 1789, Robert Ransome established a ploughshare casting business in a disused malting at St Margaret's Ditches, Ipswich, with an investment of £200 and a single employee. His fortune was assured by a technological breakthrough in 1803 when, as a result of an accident in the foundry, a mould broke open spilling molten iron onto the cold floor. After the liquid solidified the iron was found to be particularly hard and it was realised that this was due to its rapid cooling. Ransomes exploited this chance find to produce a strong, "self-sharpening" ploughshare, a revolutionary agricultural implement. Moulds were made of sand on the upper side and iron on the lower side; liquid iron poured into the mould cooled most rapidly on the lower side, forming a hard edge there. In use, the softer side of the ploughshare wore away most quickly, leaving a sharp edge against the hard side. (The iron side of the mould was referred to as a chill and the whole casting was referred to as chilled cast iron.) Rapid expansion of the company followed. In 1835, the firm, previously run exclusively by members of the Ransomes family, recruited an engineer by the name of Charles May (1800-1860), subsequently changing its name to Ransomes and May. In the wake of the great agricultural depression of the early 19th century, under Charles' influence, Ransomes and May diversified to produce many items in addition to those associated with agriculture, including bridge building, millwrighting, lawnmowers, traction engines, railway fitments, the installation of the first domestic gas supplies to Ipswich and mountings for astronomical telescopes and associated fittings in observatories. By 1849, the firm had transferred operations to the Orwell Works in a former shipyard on the River Orwell, and employed more than 1000 people. Over the ensuing years the company grew and became the principal employer in Ipswich.

In 1851, the Great Exhibition was held in Hyde Park, London and, naturally, Ransomes was represented there. The firm wanted something spectacular to display, so constructed a telescope, on a German equatorial mount, around an 11" object glass by Ross of London. Also in that year, Charles May (who by this time had moved into a house in Bolton Lane, Ipswich) persuaded the British Association for the Advancement of Science to hold its annual meeting, not in London, but in Ipswich. He later considered this the highlight of his career! (After 1851, he moved to London and acted as an expert witness in engineering-related legal disputes.)

In 1966, the firm moved to a 250 acre site at Nacton (now Ransomes Europark) purchased earlier from the Pretyman family. Unfortunately, by this time the firm was in commercial decline and, by the end of 1966, was purchased in part by an American conglomerate. (Note that the company had no less than ten variations in its trading name during its 211 year existence as various partners bought into or out of it [1].)

Trophy Ransomes Trophy telescope at the Great Exhibition, 1851.

The Royal Greenwich Observatory

Charles II founded the Royal Greenwich Observatory in 1675 to solve the problem of determining longitude at sea. According to the royal warrant of 22 June 1675: we have resolved to build a small observatory within our park at Greenwich upon the highest ground. John Flamsteed was appointed the King's "Astronomical Observator" (later to become the post of Astronomer Royal) to catalogue the heavens accurately for the purposes of navigation. Designed by Christopher Wren [2] and built on a budget [3] of £500 with recycled materials purloined from the Tower of London and Tilbury Fort, the observatory originally consisted of the famous octagonal room plus basic accommodation for the Observator.

It was not until almost a century had passed that the problem of determining longitude at sea was finally solved, in part by stellar cataloguing and study of the Moon's motion, but mainly by the availability of accurate chronometers produced by John Harrison (a fascinating story in its own right). As a direct result of the work to determine longitude, Greenwich was eventually selected as the location marking the prime meridian (0° longitude). Over the ensuing years and under successive Astronomers Royal the observatory expanded and branched into many areas of astronomical research, maintaining its position as a world leader over the 323 years of its existence.

As a result of urban sprawl with its associated light pollution and the coming of the electrified railway, which played havoc with the RGO's terrestrial magnetic field readings, at the end of World War II the decision was made to move the observatory to Herstmonceux Castle in East Sussex. From 1958 until 1990 Herstmonceux was the home of the RGO until it moved again to Cambridge. Unfortunately, in April 1998, as part of the quest by PPARC [4] for "value for money", the RGO notified all its staff of redundancy and later that year its 323-year history came to an end.

ROG The RGO in the late 17th Century.

George Biddell Airy (1801-92)

Airy hailed from Playford in Suffolk. He was a mathematician who, by the age of 27, had held both the prestigious Lucasian and Plumian professorships at Cambridge University and was a director of Cambridge Observatory. He published over 500 papers and 12 books. He also held the Presidency of the Royal Astronomical Society, had a civil list pension (in his wife's name), declined a knighthood and, in 1835, was appointed seventh Astronomer Royal.

His reputation was that of a man methodical beyond belief with an extraordinary flair for effective administration. He set a standard of efficiency which became a benchmark of the RGO - the Airy tradition, as it became known. A born leader who inspired his staff to ever greater endeavour, he was loathe to disparage any of the existing observatory instruments but gradually replaced them with new equipment, whilst never demanding more resource than actually needed for any particular research task. This approach invariably let Airy get his way and his knowledge and confidence in the abilities of contemporary mechanical engineers, optical engineers and instrument makers ensured that he could specify very precisely the instrumentation that he required. He summed up his dedication to the position of Astronomer Royal thus:

I am not a mere Superintendent of current observations, but a Trustee for the honour of Greenwich Observatory generally and for its general utility in the world.

Upon his appointment as Astronomer Royal, Airy set about alterations to both the accommodation and instrumentation of the RGO. New living rooms were added to Flamsteed's original quarters, along with changes to the Octagon, Computing [5] and Quadrant rooms. From 1836, Airy embarked upon a complete re-equipping of the RGO, starting with a new magnetic observatory to the south of the main buildings, aligned to the magnetic meridian. During 1844, at the south-western corner, work commenced on a three-storey altazimuth dome which was sited upon the original walls from Flamsteed's time. During the re-equipping, Airy installed several instruments made in total or in part by Ransomes: these are described below.

ROG George Biddell Airy from a lithograph by T H Maguire, 1852.

Airy's achievements whilst at Greenwich are legion and too many to list fully here. Not least amongst them, he was instrumental in the standardisation of time throughout the British Isles via the railway telegraph system. Airy retired from the post of Astronomer Royal in 1881, finally accepting the knighthood which had been on offer for many years. He kept his links with the RGO via his election to the board of visitors, upon which he served until his death in 1892.

Altazimuth Instrument (1847)

Airy convinced the Board of Visitors of the RGO of the need for an instrument constructed on principles of extraordinary firmness for accurate measurement of the Moon's motion [6]. At the time, certain parts of the Moon's orbit had not been accurately measured (not least two days on either side of new moon due to solar glare). In 1843, Airy placed an order with Ransomes & May of Ipswich for castings and an order with Troughton & Simms of London for a 360° azimuth circle and optics. This was the first of Ransomes' products which Airy installed at the RGO.

The instrument did not achieve first light until 16 May 1847 due to an unexplained accident during manufacture at Ransomes [7] and minor delays in setting up. The instrument was essentially a transit circle, capable of being turned to any azimuth and altitude, and was used to obtain accurate lunar positions which were compared daily with the published lunar tables of the time. The instrument remained in use until 1899 when a new altazimuth instrument was brought into use. However, that was not the end for the Airy instrument and, during 1900 - 1910, it was used for work on lunar occultations. However, the dome was required by 1910 to house a new photoheliograph and the instrument was dismounted, eventually being placed on exhibition in the Science Museum. The dome was demolished in 1947.

Paramount in Airy's design was the need for firmness of construction, which was achieved by using as few principle parts as possible. The instrument was mounted on a cylindrical brick pier 26 feet high and 3 feet diameter. The major fixed parts of the instrument comprised the pivot of the vertical axis and the horizontal graduated circle. The movable part of the instrument, weighing just under one ton, consisted of four iron castings which carried the telescope together with micrometers, levels, lamp, reflectors and other paraphernalia for reading the graduations indicating the coordinates to which the telescope was pointing. Ransomes mounted a large name plate on one of the side panels of the instrument.

Airy Altazimuth 1 The Airy Altazimuth Instrument. The Ransomes & May maker's plate is clearly visible. (The Illustrated London News.)

Airy Altazimuth 2 The Airy Altazimuth Instrument. (Courtesy of the National Maritime Museum.)

Transit Circle (1850)

In 1848 Airy arranged for the Admiralty to purchase from Simms an 8" object glass with a focal length of 11' 6". Around this glass he designed a state of the art transit circle. Ransomes & May built all the engineering components and, once again, Troughton & Simms produced the optical and instrumental items. The transit telescope was mounted on two piers - one of granite and the other of Portland stone - via two 6" diameter pivots made with Ransomes' famed "chilled cast iron". The whole assembly weighed 1,890 lbs. The roof shutter mechanism is a classic example of Airy's eye for minute detail - just before the shutters reach the fully open or fully closed positions a hammer strikes a bell as a warning to the person who turns the winch that he must move it gently.

Airy's Transit Circle superseded the transit circle of James Bradley (3rd Astronomer Royal) at the RGO and the instrument of Sir James South at nearby Blackheath which, from 1806, was considered the most successful of its type in the world. Bradley's instrument had defined the prime meridian of Britain, adopted by the Ordnance Survey (OS) from the time of the first OS map in 1801 onwards. Airy's new instrument was mounted nineteen feet to the east of Bradley's and effectively redefined the prime meridian. (The first and second astronomers royal, Flamsteed and Edmond Halley, had also determined meridian lines which Bradley in turn had redefined.)

Airy's Transit Circle was in regular use until 1954, some 103 years and 600,000 observations after its installation. By 1967, the instrument had been restored to working order and is now on exhibition at the RGO and in occasional use. If you visit the observatory, have a look at the telescope tube of the instrument, where you will see two plates, proudly announcing the makers as RANSOMES & MAY ENGINEERS IPSWICH 1850.

At an International Meridian Conference held in Washington DC in 1884, twenty two nations voted that the cross hairs of the Airy Transit Instrument should define the zero meridian of the world [8]. The vote was ratified by a treaty which still holds.

Airy Transit 1 Observers using the Airy Transit Circle. (The Illustrated London News, 21 April 1923.

Airy Transit 2 The Airy Transit Circle. (Courtesy of the National Maritime Museum.)

Great Equatorial Refractor (1859)

The Great Equatorial Refractor is, perhaps, the most celebrated of Ransomes' instruments, and is the only one that the company itself ever appeared to acknowledge.

In 1845, both John Couch Adams of Cambridge and Urbain Le Verrier of Paris mathematically predicted the existence of the planet Neptune. Johann Galle in Berlin made the first optical detection of Neptune the following year, although James Challis at Cambridge had unsuccessfully searched for it for some months [9]. Victorian English public opinion was outraged and considered that the planet ought to have been discovered in England! In 1855, Airy took full advantage of the public sentiment: in an address to the Board of Visitors of the RGO he pointed out deficiencies in contemporary equatorial telescopes and pressed successfully for permission to commission a new instrument to his own design, employing a 12.8" object-glass manufactured by Merz of Munich. (At the time, the largest object-glass that British makers could successfully grind was approximately 6" in diameter. Foreign firms were better able to grind larger lenses and the company Merz of Munich was market leader for both the excellence of its object-glasses and their ready availability.)

Again, Airy contracted Troughton & Simms to produce the optical system and Ransomes & Sims the mounting. The mounting of the Great Equatorial Refractor is of the English style with the declination axis eccentric to the polar axis, permitting observation of the celestial pole. The wrought iron framework rests on a 24 feet cast iron pier (to the north) which weighs 5.5 tons. Setting circles were provided at 5 feet (declination) and 6 feet (RA) respectively. The telescope was driven by a water-powered turbine (controlled by a mercury pendulum and governor) with water supplied by the Kent Water Company. The instrument, housed in a new dome on the south-east corner of the observatory, became a wonder of the age!

The first recorded observation by the instrument was of an occultation of Jupiter on 24 May 1860. Thereafter it was used for visual observations of planets, spectroscopy and early pioneering photographic work.

By 1891, lens making had advanced to the point where much larger object glasses could be manufactured and the 12.8" OG and tube were replaced on the Ransomes mount by a new 28" refractor [10], for which a new dome was built around the mount. The 28" refractor survives at the RGO to this day. In 1892, the 12.8" telescope was installed in another dome at Greenwich and, in 1896, the OG was mounted in a new tube and fitted as a guide scope to the 26" Thompson photographic refractor at Greenwich. In 1957, the Thompson Refractor (with its guide scope) was moved to Herstmonceux.

Airy Equatorial 1 Observers using the Great Equatorial Refractor. (The Illustrated London News, 21 April 1923.

Airy Equatorial 2 The Great Equatorial Refractor. (Courtesy of the National Maritime Museum.)

Similarities Between the RGO and Orwell Park Observatory

Orwell Park Observatory became operational in 1874. The principal instrument at Orwell Park is a 10.2" equatorially mounted refractor, nowadays called the Tomline Refractor. There are some clear similarities and links between the RGO and Orwell Park Observatory:

Ransomes' Part in the Construction of Orwell Park Observatory

During the period 1969-73, the bulk of Ransomes' historical archives was passed to the University of Reading for conservation. Although the archives are extensive, they make only a vague passing reference to the Great Equatorial Refractor and contain no mention at all of the Altazimuth and Transit instruments at the RGO or of the Tomline Refractor at Orwell Park.

With so little information available in the archives on Ransomes' astronomical products, I extended an invitation to the late Mr Fred Dyer, C Eng, FIME to visit Orwell Park Observatory. Fred was internationally acknowledged as the leading authority on the history and products of the Ransomes company. He was apprenticed in the 1930's at Ransomes, and was the last apprentice ever to train there in steam engine engineering. He worked continuously for the company until his retirement, eventually being promoted to the post of Farm Machinery Works Manager. He wrote much on Ransomes and retained close links with both the company and the few surviving descendants of the Ransomes family (including the only direct descendant, who farmed in New Zealand). He contributed much to the archives at Reading.

Fred Dyer Fred Dyer inspects the Tomline Refractor.

It was with considerable pleasure that Fred accepted my invitation, and he visited Orwell Park in May 1998 to cast his expert eye over the telescope and its mount. He had no previous knowledge of Ransomes' telescope making activities beyond the Great Equatorial. In Fred's expert opinion, based on the style and size of the casting, the telescope mount at Orwell Park is "almost certainly" a product of the Orwell Foundry of the Ransomes, Sims & Head company. In the early 1870s, when the mount was constructed, the only other foundries capable of making a casting of such size and accuracy were likely no closer than Sheffield. (The Royal Naval Dockyards at Chatham might have had facilities to produce such a casting, but that is a remote possibility.)

The casting would have been dug into the floor of the Orwell Foundry and a wooden former would have been placed into the excavation with sand very tightly packed around. The former would then be removed and a core fashioned [12] after which molten metal would have been poured into the resulting mould. The Orwell Park mounting bears marks that were made by hardwood spindles which passed through the outer mould to hold the inside core as well as provide a means of lifting out the casting after it had cooled. The spindles were subsequently removed and their holes patched with core plugs. It is likely that the mounting would have been transported by barge downstream along the River Orwell direct from the works to the observatory.

Ransomes and other manufacturers usually placed a maker's plate on the outside of a large casting, and there is evidence of such a plate having been fitted at one time to the neck of the telescope mount; however it is not present nowadays.

A Link Between The Ransomes and Airy

Robert Ransome married a local girl, Mary Raven, and their union produced 12 children. One of these, Jane Ransome, married Arthur Biddell, a farmer and land valuer who farmed at Hall Farm, Playford. (Arthur and Jane in turn produced 10 children.) Arthur was George Biddell Airy's uncle, and a major influence on his childhood. The young Airy frequented the house at Hall Farm and draw extensively on his uncle's knowledge and excellent collection of books. It was through Arthur that Airy became acquainted with the likes of Clarkson, slave trade abolitionist, and Cubitt, the famous Victorian engineer. Anecdotal evidence suggests that Airy made his first astronomical observation when he was shown the planet Saturn through a 2" refractor constructed by Robert Ransome.

The picture below shows Arthur Biddell. It is thought to have been taken circa 1855-60 and may be one of the earliest paper printed photographs in existence (the paper photographic process was invented in 1850). Arthur is sitting in the entrance porch at Hall Farm and that scene is very little changed to this day. Anna Airy (grand-daughter of George Biddell Airy) endorsed the back of the photo in 1925, writing that Arthur didn't generally pose for pictures as it was against his religious principles and he regarded it as "the making of graven images"! He is wearing old fashioned knee breeches and was famed as possibly the last of his generation - in a very wide area - to wear them. Airy, while at Trinity College, Cambridge, was famed as the last student to wear such garments on campus, perhaps demonstrating his uncle's influence.

Arthur Biddell Arthur Biddell on his porch at Hall Farm.

While Astronomer Royal, Airy retained his country retreat at Playford, near his uncle's farm, and this, perhaps, kept alive his family associations with the area. It is no surprise that, when he came to modernise the telescopes at Greenwich, his familiarity with Ransomes and a knowledge both of the firm's technical capabilities and its senior personnel led him to place so much work with it.

Observatories and Telescopes Constructed by Ransomes

Name, Location, Date Details of Telescope Notes Where Now
Airy Altazimuth, Greenwich, 1847 3.75" OG by Troughton & Simms on altazimuth mount Used to extend observations by the Transit Telescope. Relatively small aperture on a massive mounting. Graduated circles on both axes. Superseded by larger instrument in 1910. [13] Science Museum reserve collection
Arthur Kett Barclay’s Observatory, Bury Hill, Dorking, Surrey, circa 1848 5.9" OG, maker unknown, on German Equatorial mount Dome by Ransome and May. [14] Observatory no longer in existence
Airy Transit Circle, Greenwich, 1851 8" OG by Troughton & Simms on altitude mount Marks prime meridian of the world. First instrument in UK to combine transit telescope and mural circle. Altitude circle (6ft in diameter) first to be divided by machine. [15] Still in situ
Trophy, Wester Elchies, Scotland, 1850 11" OG by Ross on German Equatorial mount Shown at Great Exhibition of 1851 on a Ransomes stand, re-erected in Scotland by James William Grant (1788-1865). Climate and owner's poor health limited use of the telescope. C P Smyth, Astronomer Royal for Scotland, described the telescope as "excellent". [16] Lost following owner's death
Great Equatorial, Greenwich, 1859 12.8" OG by Merz & Son on English Equatorial mount Originally housed in a "Drum Dome". "Onion Dome" constructed when OG replaced with 28" version in 1893. North pier largest single iron casting up to that time. [17] Still in situ, occasional amateur use
Airy Transit, Royal Observatory, Cape of Good Hope, South Africa, 1855 8" OG (maker unknown), on altitude mount Copy of Airy Transit Circle? Only part still existing is eyepiece micrometer in Cape Town Observatory Museum. [18] Dismantled in 1960
Orwell Park, Nacton, Nr, Ipswich, 1874 10.2" OG by Merz & Mahler on German Equatorial mount Colonel Tomline’s private observatory [18] Still in situ, regular amateur use
Spanish Naval Observatory, Cadiz, 1859 Unknown Possible second copy of the Airy Transit Circle? [19] Unknown


Considering the extensive experience of Ransomes in the construction of astronomical telescopes and mounts, the evidence of extensive collaboration between Airy, Troughton & Simms and Ransomes and the expert opinion of Fred Dyer, there can be little doubt that the mount of the Orwell Park Refractor was cast by Ransomes.



The family all followed the Quaker tradition.


Wren, although immortalised for his architectural feats, was in fact a Professor of Astronomy.


The £500 was raised by selling the French a quantity of spoiled gunpowder.


The Particle Physics and Astronomy Research Council, funding body for the RGO.


That is computing in the old sense of "clerk & quill", pouring over countless figures representing observational measurements.


Using the compelling argument that the RGO had been founded expressly to study lunar motion for the aid of mariners.


Ransomes may have encountered difficulties in casting what was certainly a new breed of scientific product.


San Domingo voted against and France and Brazil abstained. The French, with classic Gallic indifference, defined Paris as the initial meridian for another thirty years, until they finally capitulated.


There is evidence that both Galileo and Herschel had observed Neptune many years previously but neither had recognised it for what it was.


To this day, the largest refractor in the UK and the eighth largest in the world.


Comparisons ware made by turning both telescopes onto bright double stars and comparing the separations and diffraction rings.


The inner core would have been made of anything that came to hand which could be moulded to shape and easily broken out afterwards. The preferred substance to pack in tightly was a mix of sand, straw and horse droppings.


Greenwich Observations 1847, Appendix.


John Weale, "Observatories of London and Vicinity", 1851.


Greenwich Observations 1852, Appendix 1.


Letter from Professor Grant, Glasgow Observatory, to the editor, MNRAS, vol. 23, no. 1, 14 November 1862, pp.1-6..


Greenwich Observations 1868, Appendix 3.


"Graces Guide" to British industrial history, entry for George Arthur Biddell (1824-1901), para 7..


See p.6 of Greenwich Observatory Annual Report for 1859, also p.52 of "Aproximación histórica al desarrollo de la astronomía en España" by I F Pérez, 2009 [20].


In translation the text reads: The meridian circle was purchased from Troughton and Simms. It was completed in 1859, but it would still take four years to begin the observations. Until 1869, these observations were scarce (aimed primarily at the training of observers). This might refer to the same instrument.

Ken Goward, FRAS, Bill Barton, FRAS