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

very greatly superior to what it had been before. Still it is not satisfactory to us, and at this time a strong chain is in preparation, to support the mirror edgeways instead of the posts that there were at first or the iron hoop which we had on it yesterday.

Nobody would have conceived that an edgewise gripe of such a mass of metal could derange its form in this way.

Last night was the finest night we have had as regards clouds, though perhaps not the best for definition of objects.


THE CASTLE, PARSONSTOWN,
_1848, Sept. 2_.

I cannot learn that the fault in the mirror had been noticed before, but I fancy that the observations had been very much confined to the Zenith and its neighbourhood.


1849

"In July the new constant-service water-pipes to the Observatory were laid from Blackheath. Before this time the supply of water to the Observatory had been made by a pipe leading up from the lower part of the Park, and was not constant.--In May the new staircase from my dwelling-house to the Octagon Room was commenced.--In the Report to the Visitors there is a curious account of Mr Breen's (one of the Assistants) personal equation, which was found to be different in quantity for observations of the Moon and observations of the Stars.--The most important set of observations (of planets) was a series of measures of Saturn in four directions, at the time when his ring had disappeared. They appear completely to negative the idea that Saturn's form differs sensibly from an ellipsoid.--Among the General Remarks of the Report the following appears: 'Another change (in prospect) will depend on the use of galvanism; and as a probable instance of the application of this agent, I may mention that, although no positive step has hitherto been taken, I fully expect in no long time to make the going of all the clocks in the Observatory depend on one original regulator. The same means will probably be employed to increase the general utility of the Observatory, by the extensive dissemination throughout the kingdom of accurate time-signals, moved by an original clock at the Royal Observatory; and I have already entered into correspondence with the authorities of the South Eastern Railway (whose line of galvanic communication will shortly pass within nine furlongs of the Observatory) in reference to this subject.'--I agreed with Schumacher in giving no medal to Mr G. P. Bond; his comet was found to be Petersen's. Five medals were awarded for comets in 1847 (Hind, Colla, Mauvais, Brorsen, Schweizer).--The Liverpool Observatory was finished this year: and the thanks of the Town Council were presented to me.--Respecting Fallows's Observations at the Cape of Good Hope: I had received the Admiralty sanction for proceeding with calculations in 1846, and I employed computers as was convenient. On July 20th of this year I was ready with final results, and began to make enquiries about Fallows's personal history, and the early history of the Cape Observatory. On Oct. 23rd I applied for sanction for printing, which was given, and the work was soon finished off, in the Astronomical Society's Memoirs.--In the month of March I had commenced correspondence with various persons on the imperfect state of publication of the British Survey. Sheets of the Map were issued by scores, but not one of them had an indication of latitude or longitude engraved. I knew that great pains had been taken in giving to the principal triangulation a degree of accuracy never before reached, and in fixing the astronomical latitudes of many stations with unequalled precision. Finally I prepared for the Council of the Royal Society a very strong representation on these subjects, which was adopted and presented to the Government. It was entirely successful, and the Maps were in future furnished with latitude and longitude lines.--I was elected President of the Royal Astronomical Society on Feb. 9th.--In June I went with Sheepshanks to see some of the operation of measuring a Base on Salisbury Plain. The following extract from a letter to his wife dated 1849, June 27th, relates to this expedition: 'In the morning we started before eight in an open carriage to the Plain: looking into Old Sarum on our way. The Base is measured on what I should think a most unfavourable line, its north end (from which they have begun now, in verification of the old measure) being the very highest point in the whole plain, called Beacon Hill. The soldiers measure only 252 feet in a day, so it will take them a good while to measure the whole seven miles. While we were there Col. Hall (Colby's successor) and Yolland and Cosset came.'"

Of private history: "I made short visits to Playford in January, April and July. From July 28th to Sept. 12th I made an expedition with my wife to Orkney and Shetland.--From Dec. 24th to 26th I was at Hawkhurst, on a visit to Sir John Herschel."


1850

"The Report to the Board of Visitors opens with the following paragraph: 'In recording the proceedings at the Royal Observatory during the last year, I have less of novelty to communicate to the Visitors than in the Reports of several years past. Still I trust that the present Report will not be uninteresting; as exhibiting, I hope, a steady and vigorous adherence to a general plan long since matured, accompanied with a reasonable watchfulness for the introduction of new instruments and new methods when they may seem desirable.'--Since the introduction of the self-registering instruments a good many experiments had been made to obtain the most suitable light, and the Report states that 'No change whatever has been made in these instruments, except by the introduction of the light of coal-gas charged with the vapour of coal-naptha, for photographic self-registration both of the magnetic and of the meteorological instruments.... The chemical treatment of the paper is now so well understood by the Assistants that a failure is almost unknown. And, generally speaking, the photographs are most beautiful, and give conceptions of the continual disturbances in terrestrial magnetism which it would be impossible to acquire from eye-observation.' --Amongst the General Remarks of the Report it is stated that 'There are two points which have distinctly engaged my attention. The first of these is, the introduction of the American method of observing transits, by completing a galvanic circuit by means of a touch of the finger at the instant of appulse of the transiting body to the wire of the instrument, which circuit will then animate a magnet that will make an impression upon a moving paper. After careful consideration of this method, I am inclined to believe that, in Prof. Mitchell's form, it does possess the advantages which have been ascribed to it, and that it may possess peculiar advantages in this Observatory, where the time-connection of transits made with two different instruments (the Transit and the Altazimuth) is of the highest importance.... The second point is, the connection of the Observatory with the galvanic telegraph of the South Eastern Railway, and with other lines of galvanic wire with which that telegraph communicates. I had formerly in mind only the connection of this Observatory with different parts of the great British island: but I now think it possible that our communications may be extended far beyond its shores. The promoters of the submarine telegraph are very confident of the practicability of completing a galvanic connection between England and France: and I now begin to think it more than possible that, within a few years, observations at Paris and Brussels may be registered on the recording surfaces at Greenwich, and vice versa.'--Prof. Hansen was engaged in forming Lunar Tables from his Lunar Theory, but was stopped for want of money. On Mar. 7th I represented this privately to Mr Baring, First Lord of the Admiralty; and on Mar. 30th I wrote officially to the Admiralty, soliciting _L150_ with the prospect, if necessary, of making it _L200_. On Apr. 10th the Admiralty gave their assent. The existence of Hansen's Lunar Tables is due to this grant.--The King of Denmark's Medal for Comets was discontinued, owing to the difficulties produced by the hostility of Prussia.--On Aug. 1st I gave to the Treasury my opinion on the first proposal for a large reflector in Australia: it was not strongly favourable.--In August, being (with my wife and Otto Struve) on a visit to Lady Breadalbane at Taymouth Castle, I examined the mountain Schehallien.--As in other years, I reported on several Papers for the Royal Society, and took part in various business for them.--In the Royal Astronomical Society I had much official business, as President.--In March I communicated to the Athenaeum my views on the Exodus of the Israelites: this brought me into correspondence with Miss Corbaux, Robert Stephenson, Capt. Vetch, and Prof. J.D. Forbes.--In December I went to the London Custom House, to see Sir T. Freemantle (Chairman of Customs), and to see how far decimal subdivisions were used in the Custom House."

Of private history: "From Mar. 19th to 22nd I was on an expedition to Folkestone, Dover, Dungeness, &c.--From Apr. 3rd to 8th at Playford, and again for short periods in June and July.--From Aug. 1st to Sept. 5th I was travelling in Scotland with my wife and Otto Struve (for part of the time). At Edinburgh I attended the Meeting of the British Association, and spoke a little in Section A. I was nominated President for 1851 at Ipswich. We travelled to Cape Wrath and returned by Inverness and the Caledonian Canal.--I was at Playford for a short time in October and December."


1851

"In this year the great shed was built (first erected on the Magnetic Ground, and about the year 1868 transferred to the South Ground).--The chronometers were taken from the old Chronometer Room (a room on the upper story fronting the south, now, 1872, called Library 2) and were put in the room above the Computing Room (where they remained for 10 or 12 years, I think): it had a chronometer-oven with gas-heat, erected in 1850.--The following passage is quoted from the Report to the Visitors:--'As regards Meridional Astronomy our equipment may now be considered complete. As I have stated above, an improvement might yet be made in our Transit Circle; nevertheless I do not hesitate to express my belief that no other existing meridional instrument can be compared with it. This presumed excellence has not been obtained without much thought on my part and much anxiety on the part of the constructors of the instrument (Messrs Ransomes and May, and Mr Simms). But it would be very unjust to omit the further statement that the expense of