Autobiography of Sir George Biddell Airy - George Biddell Airy (android based ebook reader txt) 📗

CHAPTER IV.

AT CAMBRIDGE OBSERVATORY. FROM HIS TAKING
CHARGE OF THE CAMBRIDGE OBSERVATORY TO HIS
RESIDENCE AT GREENWICH OBSERVATORY AS ASTRONOMER
ROYAL.

FROM MARCH 15TH 1828 TO JAN. 1ST 1836.


1828

"I attended a meeting of the Board of Longitude on Apr. 3rd. And again on June 4th; this was the last meeting: Sheepshanks had previously given me private information of the certainty of its dissolution.--On Apr. 4th I visited Mr Herschel at Slough, where one evening I saw Saturn with his 20-foot telescope, the best view of it that I have ever had.--In June I attended the Greenwich Observatory Visitation.--Before my election (as Plumian Professor) there are various schemes on my quires for computation of transit corrections, &c. After Apr. 15th there are corrections for deficient wires, inequality of pivots, &c. And I began a book of proposed regulations for observations. In this are plans for groups of stars for R.A. (the Transit Instrument being the only one finished): order of preference of classes of observations: no reductions to be made after dinner, or on Sunday: no loose papers: observations to be stopped if reductions are two months in arrear: stars selected for parallax.--The reduction of transits begins on Apr. 15th. On May 15th Mr Pond sent me some moon-transits to aid in determining my longitude.--Dr Young, in a letter to me of May 7th, enquires whether I will accept a free admission to the Royal Society, which I declined. On May 9th I was elected to the Astronomical Society.--Towards the end of the year I observed Encke's Comet: and determined the latitude of the Observatory with Sheepshanks's repeating circle.--On my papers I find a sketch of an Article on the Figure of the Earth for the Encyclopaedia Metropolitana.

"As early as Feb. 23rd I had been in correspondence with T. Jones, the instrument-maker, about pendulums for a repetition of the Dolcoath Experiments. Invitations had been received, and everything was arranged with Whewell. Sheepshanks, my brother, and Mr Jackson of Ipswich (Caius Coll.) were to go, and we were subsequently joined by Sedgwick, and Lodge (Magdalene Coll.). On July 3rd Sheepshanks and I started by Salisbury, taking Sherborne on our way to look at the church, which had alarmed the people by signs of a crack, and arrived at Camborne on July 8th. On the 14th we set up the pendulums, and at once commenced observations, our plan being, to have no intermission in the pendulum observations, so that as soon as the arc became too small a fresh series was started. On July 29th we raised the instruments, and Sheepshanks, who managed much of the upper operations, both astronomical and of pendulums, mounted the pendulums together in his observatory. We went on with our calculations, and on August 8th, on returning from a visit to John Williams at Barncoose, we heard that there was a 'run' in Dolcoath, that is a sinking of the whole mass of rock where it had been set free by the mine excavations: probably only a few inches, but enough to break the rock much and to stop the pumps. On Aug. 10th the calculations of our observations shewed that there was something wrong, and on the 13th I perceived an anomaly in the form of the knife edge of one pendulum, and of its agate planes, and suggested cautions for repeating the observations. We determined at once to repeat them: and as the water was rising in the mine there was no time to be lost. We again sent the instruments down, and made observations on the 16th, 17th and 18th. On the 19th I sent the instruments up, for the water was near our station, and Sedgwick, Whewell, and I went on a geological expedition to the Lizard. On our return we met Sheepshanks and the others, and found the results of the last observations unsatisfactory. The results of comparing the pendulums were discordant, and the knife edge of the faulty pendulum had very sensibly altered. We now gave up observations, with the feeling that our time had been totally lost, mainly through the fault of the maker of the pendulum (T. Jones). On the 28th we made an expedition to Penzance and other places, and arrived at Cambridge on the 17th of September.

"In the course of the work at Dolcoath we made various expeditions as opportunity offered. Thus we walked to Carn Brea and witnessed the wrestling, the common game of the country. On another occasion Sedgwick, Whewell, and I had a capital geological expedition to Trewavas Head to examine granite veins. We visited at Pendarves and Trevince, and made the expedition to the Lizard already referred to, and saw many of the sights in the neighbourhood. After visiting Penzance on the conclusion of our work we saw Cape Cornwall (where Whewell overturned me in a gig), and returned homewards by way of Truro, Plymouth (where we saw the watering-place and breakwater: also the Dockyard, and descended in one of the working diving-bells), Exeter, Salisbury, and Portsmouth. In returning from Camborne in 1826 I lost the principal of our papers. It was an odd thing that, in going through Exeter on our way to Camborne in 1828, I found them complete at Exeter, identified to the custodian by the dropping out of a letter with my address.

"On my return to Cambridge I was immediately immersed in the work of the Observatory. The only instrument then mounted at the Observatory was the Transit. I had no Assistant whatever.--A Mr Galbraith of Edinburgh had questioned something in one of my Papers about the Figure of the Earth. I drew up a rather formal answer to it: Whewell saw my draft and drew up a much more pithy one, which I adopted and sent to the Philosophical Magazine.--For comparing our clocks at the upper and lower stations of Dolcoath we had borrowed from the Royal Observatory, Greenwich, six good pocket chronometers: they were still in the care of Mr Sheepshanks. I arranged with him that they should be sent backwards and forwards a few times for determining the longitude of Cambridge Observatory. This was done on Oct. 21st, 22nd, 23rd: the result was 23 deg.54, and this has been used to the present time (1853). It evinced an error in the Trigonometrical Survey, the origin of which was found, I think, afterwards (Dr Pearson in a letter of Dec. 17th spoke of the mistake of a may-pole for a signal-staff). I drew up a Paper on this, and gave it to the Cambridge Philosophical Society on Nov. 24th. (My only academical Paper this year.)--I had several letters from Dr Young, partly supplying me with calculations that I wanted, partly on reform or extension of the Nautical Almanac (which Dr Young resisted as much as possible). He considered me very unfairly treated in the dissolution of the Board of Longitude: Professor Lax wished me to join in some effort for its restoration, but I declined.

"As my reduction of observations was kept quite close, I now began to think of printing. In regard to the form I determined to adopt a plan totally different from that of any other observations which I had seen. The results were to be the important things: I was desirous of suppressing the separate wires of transits. But upon consulting Herschel and other persons they would not agree to it, and I assented to keeping them. I applied to the Press Syndicate to print the work, and on Nov. 10th at the request of T. Musgrave (afterwards Archbishop of York) I sent a specimen of my MS.: on Nov. 11th they granted 250 copies, and the printing soon commenced."


1829

"During a winter holiday at Playford I wrote out some investigations about the orbits of comets, and on Jan. 23rd 1829 I returned to Cambridge. The Smith's Prize Examination soon followed, in which I set a Paper of questions as usual. On Feb. 18th I made notes on Liesganig's geodetic work at the British Museum.

"I was naturally anxious now about the settlement of my salary and of the Observatory establishment. I do not know when the Syndicate made their Report, but it must have been in the last term of 1828. It recommended that the salary should be annually made up (by Grace) to _L500_: that an Assistant should be appointed with the assent of the Vice-Chancellor and dismissable by the Plumian Professor: and that a Visiting Syndicate should be appointed, partly official and partly of persons to be named every year by Grace. The Grace for adopting this Report was to be offered to the Senate on Feb. 27th. The passing of the Grace was exposed to two considerable perils. First, I found out (just in time) that a Senior Fellow of Trinity (G.A. Browne) was determined to oppose the whole, on account of the insignificant clause regarding dismissal of Assistants, which he regarded as tyrannical. I at once undertook that that clause should be rejected. Secondly, by the absurd constitution of the 'Caput' at Cambridge, a single M.A. had the power of stopping any business whatever, and an M.A. actually came to the Senate House with the intention of throwing out all the Graces on various business that day presented to the Senate. Luckily he mistook the hour, and came at 11 instead of 10, and found that all were dispatched. The important parts of the Grace passed without any opposition: but I mustered some friends who negatived that part which had alarmed G.A. Browne, and it was corrected to his satisfaction by a new Grace on Mar. 18th. I was now almost set at rest on one of the great objects of my life: but not quite. I did not regard, and I determined not to regard, the addition to my salary as absolutely certain until a payment had been actually made to me: and I carefully abstained, for the present, from taking any steps based upon it. I found for Assistant at the Observatory an old Lieutenant of the Royal Navy, Mr Baldrey, who came on Mar. 16.

"On May 4th I began lectures: there were 32 names. The Lectures were improving, especially in the optical part. I do not find note of the day of termination.--I do not know the actual day of publication of my first small volume of Cambridge Observations, 1828, and of circulation. The date of the preface is Apr. 27th 1829. I have letters of approval of it from Davies Gilbert, Rigaud, and Lax. The system which I endeavoured to introduce into printed astronomical observations was partially introduced into this volume, and was steadily improved in subsequent volumes. I think that I am justified, by letters and other remarks, in believing that this introduction of an orderly system of exhibition, not merely of observations but of the steps for bringing them to a practical result--quite a novelty in astronomical publications--had a markedly