The Builders and Assistants
There were a number of people and companies involved in the construction of the telescope. We know that Craig had approached several individuals that had expert knowledge in various aspects of the telescope's design, engineering and construction.
We can readily tie up how most of the engineers were acquainted although the direct link between Craig and the others is unknown. William Gravatt and George Rennie had both worked quite extensively on the Thames Tunnel Crossing. They were also members of the Royal Society and while Gravatt had joined the Royal Astronomical Society by the early 1840s, Rennie was elected by the mid 1850s.
Gravatt was clearly a liked man. During his residency in London he had made some kind of connection with Richard Beard, the victorian portrait photographer. They had both lived at 34 Parliament Street. It is quite probable that Beard had been told specific information about the Craig Telescope, so that when he came to photograph it in 1852 for the Illustrated London News, he would already have been predisposed to all the idiosyncrasies of the instrument, portraying it from its best side. If the telescope had not yet been completed, then it was easier for Beard to have known what else needed to be added or modified, assisting the engraver who had been commissioned by the publication to created the telescope's likeness.
Our knowledge of Thomas Slater's connection with the project is much more scant. We know he was about 33 years old when asked by either Gravatt or Craig to help in the telescope's construction. It would have taken him about two years to complete the figuring of the two components of the 24-inch lens. At that time he was not a member of the Royal Astronomical Society for he joined later in 1858. However, one of his proposers was John Lee, a keen amateur astronomer and antiquary and a fellow of the Royal Astronomical Society. In 1830, Lee had his own private observatory at Hartwell, housing a 6-inch refractor. No doubt, Slater's knowledge of refractors was a passion the two men enjoyed. Perhaps they had known each other some time and when Slater wanted membership of the Royal Astronomical Society, Lee was quite ready to help.
Lee was also known to George Rennie, proposing him in 1856. Perhaps the connection between Thomas Slater and the others in the project, is John Lee. Continuing the link between Lee and the others, we know from an entry in the Times of February 13, 1844, he must have known the Rev. Joseph Bancroft Reade. For it mentions their observations of the Comet of Faye.
Mr William Gravatt
In 1850 Gravatt was, on account of his well-known mathematical and mechanical skills, selected to design and to superintend the construction of an Achromatic Telescope.
From the few references of his involvement it is obvious that his designs for the telescope were heavily compromised by John Craig who felt that there were engineering solutions that could be sought which would keep the costs of the project to a minimum.
Mr George Rennie
Messrs. Rennie was one of the foremost heavy-engineering firms of the 19th century, were engaged to build some of the telescope parts and fabricate the long tube assembly. Once completed it seems he did not involved himself any more with the project.
Chance Brothers
Britain had lagged behind the rest of Europe in the production of glass due to the prohibitive window tax against which astronomers campaigned to no avail, and which was not repealed until 1851, the year before Craig built his monster refractor.
Chance & Hunt Ltd has always considered its foundation year to be 1835, the year in which Chance and Hartleys of Smethwick, very soon to become the famous firm of Chance Brothers and Company, glassmakers was formed. Products manufactured included saltcake, Hydrochloric Acid and Soda Ash.
The Chance Brothers of Smethwick were the British Commonwealth leading optical-instrument firm. In 1888 the chance brothers went on to cast the 28-inch object lens of the (at the time) Royal Greenwich Observatory. The lens was in fact cast out of two components, one of flint and the other of plate glass. Making the flint-glass blanks was the responsibility of Mr Chance of Birmingham. While the plate-glass disk was cast by the Thames Plate Glass Company.
Mr Thomas Slater
It is probable that Craig had asked several lens makers to take up the challenge of the world's largest achromatic lens before he came across Slater. One such individual would probably have been Andrew Ross. He was well known to several eminent astronomers including George Biddell Airy, the Astronomer Royal at that time, who said in a report of the British Association for the Advancement of Science in 1851, "The removal of the vexatious fiscal interferences with the manufacture of glass, and the enterprise with which Mr Chance as manufacturer and Mr Simms and Mr Ross as opticians, have taken up the construction of large object-glasses, promise to lead to the most gratifying results. Already Mr Simms has partially tested object glasses of 13-inches aperture; and one of 16-inches is waiting not for the flint but for the crown lens. Mr Ross, it is understood, has ground an object-lens of 2-feet aperture; but it has yet to be tested". Perhaps Mr Ross turned down the offer because he was already committed to the construction of several large aperture lenses.
We know nothing of the work Slater put into the project, but we do know that it was probably done at Somers Place and that it was not a total success; one of the lenses being slightly undercorrected. |
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In 1850 Craig had probably started his ideas for the Telescope. As such it might be an idea to see how old each of those that worked on the telescope were at that time.
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