The state of things with regard to Lord Rosse's Telescope is this. If a night is fine, it is wanted for his use or for the use of professional astronomers. If it is not fine, it is of no use to anybody. Now considering this, and considering that the appropriation of the telescope on a fine night to any body but a technical astronomer is a misapplication of an enormous capital of money and intellect which is invested in this unique instrument--it is against my conscience to ask Lord Rosse to place it at the service of any person except an experienced astronomer. No introduction, I believe, is necessary for seeing it in the day-time. The instrument stands unenclosed in the Castle Demesne, to which strangers are admitted without question, I believe...............

Faithfully yours, G.B. AIRY.

1855

"On May 9th it was notified to me (I think through the Hydrographer) that the Admiralty were not unwilling to increase my salary. I made application therefore; and on Jan. 21st 1856 Sir Charles Wood notified to me that the Admiralty consented to have it raised from _800_ to _1000_.--In the Report to the Board of Visitors it appears that 'At the instance of the Board of Trade, acting on this occasion through a Committee of the Royal Society, a model of the Transit Circle (with the improvement of perforated cube, &c. introduced in the Cape Transit Circle) has been prepared for the Great Exhibition at Paris.'--Under the head of Reduction of Astronomical Observations it is stated that 'During the whole time of which I have spoken, the galvanic-contact method has been employed for transits, with the exception of a few days, when the galvanic apparatus was out of order.

From the clock errors, I have deduced the personal equations of the observers in our usual way.... The result is that the magnitude of the personal equations in the galvanic-touch method is not above half of that in the eye and ear method.'--With regard to the Reduction of the Magnetical Observations, 'I have not yet felt sufficiently satisfied with any proposed method of discussing the magnetic results to devote any time to their further treatment.'--'The Time-Signal Ball at Deal was brought into regular use at the beginning of the present year. In a short time, however, its action was interrupted, partly by derangement of the apparatus, and partly by the severity of the weather, which froze the sulphuric acid to the state of jelly. I sent an a.s.sistant and workman to put it in order, and since that time it has generally acted very well.--Application has been made to me from one of the important offices of Government (the Post Office) for the galvanic regulation of their clocks.--On considering the risks to which various galvanic communications are liable, and the financial necessity for occupying wires as little as possible, I perceived that it was necessary to devise constructions which should satisfy the following conditions. First, that a current sent once a day should suffice for adjusting the clock, even if it had gone ten or more seconds wrong. Secondly, that an occasional failure of the current should not stop the clock. I have arranged constructions which possess these characters, and the artist (Mr C. Shepherd) is now engaged in preparing estimates of the expense. I think it likely that this may prove to be the beginning of a very extensive system of clock regulation."--With respect to the operations for determining the longitude of Paris, it is stated that, "The whole number of days of signal transmission was eighteen, and the whole number of signals transmitted was 2530. The number of days considered available for longitude, in consequence of transits of stars having been observed at both Observatories, was twelve, and the number of signals was 1703. Very great care was taken on both sides, for the adjustments of the instruments. The resulting difference of longitude, 9m. 20.63s., is probably very accurate. It is less by nearly 1s. of time than that determined in 1825 by rocket-signals, under the superintendance of Sir John Herschel and Col. Sabine. The time occupied by the pa.s.sage of the galvanic current appears to be 1/12th of a second."--With regard to the Pendulum Experiments in the Harton Colliery, after mentioning that personal a.s.sistance had been sought and obtained from the Observatories of Cambridge, Oxford, Durham, and Red Hill, the Report states that "The experiments appear to have been in every point successful, shewing beyond doubt that gravity is increased at the depth of 1260 feet by 1/10000th part. I trust that this combination may prove a valuable precedent for future a.s.sociations of the different Observatories of the kingdom, when objects requiring extensive personal organization shall present themselves."--On Oct. 18th the Astronomer Royal printed an Address to the Individual Members of the Board of Visitors on the subject of a large new Equatoreal for the Observatory. After a brief statement of the existing equipment of the Observatory in respect of equatoreal instruments, the Address continues thus: "It is known to the Visitors that I have uniformly objected to any luxury of extrameridional apparatus, which would materially divert us from a steady adherence to the meridional system which both reason and tradition have engrafted on this Observatory. But I feel that our present instruments are insufficient even for my wishes; and I cannot overlook the consideration that due provision must be made for future interests, and that we are nearer by twenty years to the time when another judgment must decide on the direction which shall be given to the force of the Observatory."--"In August I had some correspondence about the Egyptian wooden astronomical tablets with Mr Gresswell and others: they were fully examined by Mr Ellis.--In this year I was much engaged on schemes for compa.s.ses, and in June I sent my Paper on Discussions of Ships' Magnetism to the Royal Society.--On Dec. 6th the mast of the Observatory time-ball broke, and the Ball fell in the Front Court.--On Aug. 4th my valued friend Mr Sheepshanks died; and on Aug. 14th I went to London to see the Standard Bars as left by him. Afterwards, on Oct. 25th I went to Reading to collect the papers about Standards left by Mr Sheepshanks.--I made a mechanical construction for Euclid I. 47, with which I was well satisfied.--On Apr. 13th I joined a deputation to the Chancellor of the Exchequer (Sir G. Cornewall Lewis) on Decimal Coinage."

Of private history: "I was at Playford for a large part of January.--On Mar, 26th I went to Reading, to visit Mr Sheepshanks, and afterwards to Silchester and Hereford.--On June 21st I went with my wife and two eldest sons to Edinburgh and other places in Scotland, but residing princ.i.p.ally at Oban, where I hired a house. Amongst other expeditions, I and my son Wilfrid went with the 'Pharos' (Northern Lights Steamer) to the Skerry Vohr Lighthouse, &c. I also visited Newcastle, &c., and returned to Greenwich on Aug. 2nd.--From Oct. 12th to 17th I was at Cambridge.--On Dec. 24th I went to Playford."

CHAPTER VII.

AT GREENWICH OBSERVATORY--1856 TO 1866.

1856

"In the Report to the Visitors there is an interesting account of the difficulties experienced with the Reflex Zenith Tube in consequence of the tremors of the quicksilver transmitted through the ground.

Attempts were made to reduce the tremor by supporting the quicksilver trough on a stage founded at a depth of 10 feet below the surface, but it was not in the smallest degree diminished, and the Report states that 'The experience of this investigation justifies me in believing that no practicable depth of trench prevents the propagation of tremor when the soil is like that of Greenwich Hill, a gravel, in all places very hard, and in some, cemented to the consistency of rock.'--With respect to the regulation of the Post Office clocks, 'One of the galvanic clocks in the Post Office Department, Lombard Street, is already placed in connection with the Royal Observatory, and is regulated at noon every day ... other clocks at the General Post Office are nearly prepared for the same regulation, and I expect that the complete system will soon be in action.'--Under the head of General Remarks a careful summary is given of the work of the Observatory, and the paragraph concludes as follows: 'Lastly there are employments which connect the scientific Observatory with the practical world; the distribution of accurate time, the improvement of marine time-keepers, the observations and communications which tend to the advantage of Geography and Navigation, and the study, in a practical sense, of the modifications of Magnetism; a careful attention to these is likely to prove useful to the world, and conducive to the material prosperity of the Observatory: and these ought not to be banished from our system.'--In September I prepared the first specification for the building to carry the S.E. Dome.--In September, learning that Hansen's Lunar Tables were finished in ma.n.u.script, I applied to Lord Clarendon and they were conveyed to me through the Foreign Office: in October I submitted to the Admiralty the proposal for printing the Tables, and in November I learned that the Treasury had a.s.sented to the expense.--Lieut.

Daynou's eclipses and occultations for longitudes of points in South Africa, observed in 1854 and 1855, were calculated here in this year.--On Feb. 16th I made my first application to Sir C. Wood (First Lord of the Admiralty) for a.s.sistance to C. Piazzi Smyth to carry out the Teneriffe Experiment: grounding it in part on the failure of attempts to see the solar prominences. He gave encouragement, and on Mar. 18th I transmitted Piazzi Smyth's Memorial to the Admiralty: on May 2nd the Admiralty authorized an expense of _500_. I drew up suggestions.--The Sheepshanks Fund: After the death of my friend Richard Sheepshanks, his sister Miss Anne Sheepshanks wished to bestow some funds in connection with the University of Cambridge, Trinity College, and Astronomy, to which his name should be attached. There must have been some conversation with me, but the first letter is one from De Morgan in August. In September I had a conversation with Miss Sheepshanks, and sent her my first draft of a scheme, to which she a.s.sented. On Sept. 30th I wrote to Whewell (Master of Trinity) who was much trusted by Miss Sheepshanks: he consented to take part, and made some suggestions. There was further correspondence, but the business did not get into shape in this year.--In connection with the Correction of the Compa.s.s in Iron Ships: I discussed the observations made in the voyage of the Royal Charter. On Feb. 13th I proposed to the Admiralty a system of mounting the compa.s.ses with adjustable magnets, and it was ordered to be tried in the Trident and Transit.--In February I reported to the Admiralty that the Deal Time-Ball had been successful, and I proposed time-b.a.l.l.s at Portsmouth, Plymouth, and Sheerness. There was much correspondence in various directions about Portsmouth and Devonport, and in March I went to Devonport and specially examined Mount Wise and the Devonport Column.--I had correspondence with Sir Howard Douglas about the sea breaking over the unfinished Dover Pier. I have an idea that this followed evidence given by me to a Harbour Commission, in which I expressed as a certainty that the sea will not be made to break by a vertical wall."

Of private history: "I returned from Playford on Jan. 18th.--From June 16th to August 5th I was, with my son Wilfrid, on an expedition to South Italy and Sicily: on our return from Sicily, we remained for three days ill at Ma.r.s.eilles from a touch of malaria.--On Dec. 22nd I went to Playford.--In acknowledgment of the pleasure which I had derived from excursions in the c.u.mberland Pa.s.ses, I made a foot-bridge over a troublesome stream on the Pa.s.s of the Sty Head."

1857

"In the Report to the Visitors, when on the subject of the Altazimuth, the following paragraph occurs: 'I alluded in a preceding section to the cutting away of a very small portion of one of the rays of the three-armed pier which carries the Altazimuth. The quality of the brickwork is the best that I have ever seen, and not a single brick was disturbed beyond those actually removed. Yet the effect was to give the Altazimuth an inclination of about 23". This inclination evidently depends on the elasticity of the brickwork.'--With reference to the new S.E. Equatoreal the Report states that 'The support of the north or upper end of the polar axis has been received, and is planted within the walls of the building in a position convenient for raising it to its ultimate destination. It is one piece of cast-iron, and weighs nearly 5 tons.'--Small changes as previously mentioned had been noticed with regard to the Zero of Azimuth of the Transit Circle, and the Report states that 'In regard to the Azimuth of the Transit Circle, and the Azimuth of its Collimator, Mr Main has brought together the results of several years, and the following law appears to hold. There is a well-marked annual periodical change in the position of the Transit Circle, the southerly movement of the eastern pivot having its minimum value in September, and its maximum in March, the extreme range being about 14 seconds; and there is a similar change, but of smaller amount, in the position of the Collimator. I cannot conjecture any cause for these changes, except in the motion of the ground. There is also a well-marked connection between the state of level of the axis and the temperature. The eastern pivot always rises when the temperature rises, the extreme range being about 6 seconds. I cannot offer any explanation of this.'--Under the head of Extraneous Works the Report states that 'The British Government had for some years past contributed by pecuniary grants to the preparation of Prof. Hansen's Lunar Tables. In the last winter they undertook the entire expense of printing a large impression of the Tables. The reading of the proof-sheets (a very considerable labour) has been effected entirely at the Observatory. I may take this opportunity of stating that the use of these Tables has enabled me, as I think, incontestably to fix the capture of Larissa to the date B.C. 557, May 19. This identification promises to prove valuable, not merely for its chronological utility, but also for its accurate determination of an astronomical epoch, the point eclipsed being exactly known, and the shadow having been very small.'--In April I gave a lecture to the Royal Astronomical Society on the methods available through the next 25 years for the determination of the Sun's parallax.--Dr Livingstone's observations for African longitudes were computed at the Observatory.--The Admiralty enquire of me about the feasibility of adopting Piazzi Smyth's construction for steadying telescopes on board ship: I gave a Report, of mixed character, on the whole discouraging.--I had correspondence with G.P. Bond and others about photographing the Stars and Moon.--On Feb. 17th Piazzi Smyth's books, &c. relating to the Teneriffe Experiment were sent to me: I recommended that an abridged Report should be sent to the Royal Society.--Respecting the Sheepshanks Fund: there was correspondence with Miss Sheepshanks and Whewell, but nothing got into shape this year: Miss Sheepshanks transferred to me _10,000_ lying at Overend and Gurney's.--In November experiments were made for the longitude of Edinburgh, which failed totally from the bad state of the telegraph wire between Deptford and the Admiralty.--In June the first suggestion was made to me by Capt. Washington for time-signals on the Lizard Point: which in no long time I changed for the Start Point.--The Admiralty call for estimates for a time-ball at Portsmouth: on receiving them they decline further proceeding.--I was engaged in speculations and correspondence about the Atlantic Submarine Cable.--In the Royal Astronomical Society, I presented Memoirs and gave lectures on the three great chronological eclipses (Agathocles, Thales, Larissa)."--On Dec. 5th Airy wrote to the Vice-Chancellor of the University of Cambridge, objecting to the proposed changes regarding the Smith's Prizes--a subject in which he took much interest, and to which he ascribed great importance.--On Apr. 27th I was in correspondence with G. Herbert of the Trinity House, about floating beacons.--In July I reported to the Treasury on the Swedish Calculating Engine (I think on the occasion of Mr Farr, of the Registrar-General's Office, applying for one).--In November I had correspondence about the launch of the Great Eastern, and the main drainage of London."

Of private history: "On Jan. 14th I returned from Playford.--From June 27th to Aug. 5th I was travelling in Scotland with my wife and two eldest sons, chiefly in the West Highlands. On our return we visited Mrs Smith (my wife's mother) at Brampton.--On Dec. 26th I went to Playford."

1858

"In the Minutes of the Visitors it is noted that the new Queen's Warrant was received. The princ.i.p.al change was the exclusion of the Astronomer Royal and the other Observatory Officers from the Board.--In the Report to the Visitors it is stated that 'The Papers of the Board of Longitude are now finally st.i.tched into books. They will probably form one of the most curious collections of the results of scientific enterprise, both normal and abnormal, which exists.'--It appears that the galvanic communications, external to the Observatory, had been in a bad state, the four wires to London Bridge having probably been injured by a thunderstorm in the last autumn, and the Report states that 'The state of the wires has not enabled us to drop the Ball at Deal. The feeble current which arrives there has been used for some months merely as giving a signal, by which an attendant is guided in dropping the Ball by hand.'--Regarding the new Equatoreal the Report states that 'For the new South-East Equatoreal, the object-gla.s.s was furnished by Messrs Merz and Son in the summer of last year, and I made various trials of it in a temporary tube carried by the temporary mounting which I had provided, and finally I was well satisfied with it. I cannot yet say that I have certainly divided the small star of gamma Andromedae; but, for such a test, a combination of favourable circ.u.mstances is required. From what I have seen, I have no doubt of its proving a first-rate object-gla.s.s.'--On March 15th was an annular eclipse of the Sun, for the observation of which I sent parties fully equipped to Bedford, Wellingborough, and Market Harborough. The observations failed totally in consequence of the bad weather: I myself went to Harrowden near Wellingborough.--Respecting the Altazimuth, the Report states that with due caution as to the zero of azimuth 'the results of observation are extremely good, very nearly equal to those of the meridional instrument; perhaps I might say that three observations with the Altazimuth are equivalent to two with the Transit Circle.'--Respecting Meteorological Observations the Report states that 'The observations of the maximum and minimum thermometers in the Thames, interrupted at the date of the last Report, have been resumed, and are most regularly maintained. Regarding the Thames as the grand climatic agent on London and its neighbourhood, I should much regret the suppression of these observations.'--After much trouble the longitude of Edinburgh had been determined: 'the r.e.t.a.r.d of the current is 0.04s very nearly, and the difference of longitudes 12m 43.05s, subject to personal equations.'--The Report concludes thus: 'With regard to the direction of our labours, I trust that I shall always be supported by the Visitors in my desire to maintain the fundamental and meridional system of the Observatory absolutely intact. This, however, does not impede the extension of our system in any way whatever, provided that such means are arranged for carrying out the extension as will render unnecessary the withdrawal of strength from what are now the engrossing objects of the Observatory.'--I had much correspondence on Comets, of which Donati's great Comet was one: the tail of this Comet pa.s.sed over Arcturus on October 5th.--Respecting the Sheepshanks Fund: In September I met Whewell at Leeds, and we settled orally the final plan of the scheme. On Oct. 27th I saw Messrs Sharp, Miss Sheepshanks's solicitors, and drew up a Draft of the Deed of Gift. There was much correspondence, and on Nov. 20th I wrote to the Vice-Chancellor of Cambridge University. A counter-scheme was proposed by Dr Philpott, Master of St Catharine's College. By arrangement I attended the Council of the University on Dec. 3rd, and explained my views, to which the Council a.s.sented. On Dec. 9th the Senate accepted the gift of Miss Sheepshanks.--I had much correspondence throughout this year, with the Treasury, Herschel, Sabine, and the Royal Society, about the continuation of the Magnetic Establishments. The Reductions of the Magnetic Observations 1848-1857 were commenced in February of this year, under the direction of Mr Lucas, a computer who had been engaged on the Lunar Reductions.--In this year I came to a final agreement with the South Eastern Railway Company about defining the terms of our connection with them for the pa.s.sage of Time Signals. I was authorized by the Admiralty to sign the 'protocol' or Memorandum of Agreement, and it was signed by the South Eastern Railway Directors.--On Aug. 28th I made my first proposal to Sir John Packington (First Lord of the Admiralty) for hourly time signals on the Start Point, and in September I went to the Start to examine localities, &c. On Dec. 23rd the Admiralty declined to sanction it.--I presented to the Royal Society a Paper about drawing a great-circle trace on a Mercator's chart.--In October I gave a Lecture on Astronomy in the a.s.sembly Room at Bury.--On Jan. 25th I was busied with my Mathematical Tracts for republication."--In this year Airy published in the Athenaeum very careful and critical remarks on the Commissioners' Draft of Statutes for Trinity College. He was always ready to take action in the interests of his old College. This Paper procured him the warmest grat.i.tude from the Fellows of the College.

Of private history: "On Jan. 23rd I returned from Playford. From July 5th to Aug. 6th I was on an expedition in Switzerland with my two eldest sons. At Paris we visited Le Verrier, and at Geneva we visited Gautier, De La Rive, and Plantamour. We returned by Brussels.--On Dec. 23rd I went to Playford."--In this year was erected in Playford Churchyard a granite obelisk in memory of Thomas Clarkson. It was built by subscription amongst a few friends of Clarkson's, and the negociations and arrangements were chiefly carried out by Airy, who zealously exerted himself in the work which was intended to honour the memory of his early friend. It gave him much trouble during the years 1856 to 1858.

Here is a letter to the Editor of the Athenaeum on some other Trinity matters:

_1858, November 22_.

DEAR SIR,

In the Athenaeum of November 20, page 650, column 3, paragraph 4, there is an account of the erection of the statue of Barrow in Trinity College Antechapel (Cambridge) conceived in a spirit hostile to the University, and written in great ignorance of the facts. On the latter I can give the writer some information.

The Marquis of Lansdowne, who was a Trinity man and whose son was of Trinity, intimated to the authorities of the College that he was desirous of placing in the antechapel a statue of _Milton_. This, regard being had to the customs and the college-feelings of Cambridge, was totally impossible. The antechapel of every college is sacredly reserved for memorials of the men of that college only; and Milton was of Christ's College. The Marquis of Lansdowne, on hearing this objection, left the choice of the person to be commemorated, to certain persons of the college, one of whom (a literary character of the highest eminence and a profound admirer of Milton) has not resided in Cambridge for many years. Several names were carefully considered, and particularly one (not mentioned by your correspondent) of very great literary celebrity, but in whose writings there is ingrained so much of ribaldry and licentiousness that he was at length given up. Finally the choice rested on Barrow, not as comparable to Milton, but as a person of reputation in his day and as the best who could be found under all the circ.u.mstances.

Cromwell never was mentioned; he was a member of Sidney College: moreover it would have been very wrong to select the exponent of an extreme political party. But Cromwell has I believe many admirers in Cambridge, to which list I attach myself.

I had no part in the negociations above mentioned, but I saw the original letters, and I answer for the perfect correctness of what I have stated. But as I am not a princ.i.p.al, I decline to appear in public.

It is much to be desired, both for the Athenaeum and for the public, that such an erroneous statement should not remain uncorrected. And I would suggest that a correction by the Editor would be just and graceful, and would tend to support the Athenaeum in that high position which it has usually maintained.

I am, dear Sir, Yours very faithfully, G.B. AIRY.

_Hepworth Dixon, Esq._

1859

"The Report to the Visitors states that 'The Lunar Reductions with amended elements (especially parallax) for correction of Observations from 1831 to 1851 are now completed. It is, I think, matter of congratulation to the Observatory and to Astronomy, that there are now exhibited the results of uninterrupted Lunar Observations extending through more than a century, made at the same place, reduced under the same superintendence and on the same general principles, and compared throughout with the same theoretical Tables.'--After reference to the great value of the Greenwich Lunar Observations to Prof. Hansen in constructing his Tables, and to the liberality of the British Government in their grants to Hansen, the Report continues thus: 'A strict comparison of Hansen's Tables with the Greenwich Observations of late years, both meridional and extra-meridional, was commenced.

The same observations had, in the daily routine of the Observatory, been compared with the Nautical Almanac or Burckhardt's Tables. The result for one year only (1852) has yet reached me, but it is most remarkable. The sum of squares of residual errors with Hansen's Tables is only one-eighth part of that with Burckhardt's Tables. When it is remembered that in this is included the entire effect of errors and irregularities of observation, we shall be justified in considering Hansen's Tables as nearly perfect. So great a step, to the best of my knowledge, has never been made in numerical physical theory. I have cited this at length, not only as interesting to the Visitors from the circ.u.mstance that we have on our side contributed to this great advance, but also because an innovation, peculiar to this Observatory, has in no small degree aided in giving a decisive character to the comparison. I have never concealed my opinion that the introduction and vigorous use of the Altazimuth for observations of the Moon is the most important addition to the system of the Observatory that has been made for many years. The largest errors of Burckhardt's Tables were put in evidence almost always by the Altazimuth Observations, in portions of the Moon's...o...b..t which could not be touched by the meridional instruments; they amounted sometimes to nearly 40" of arc, and they naturally became the crucial errors for distinction between Burckhardt's and Hansen's Tables. Those errors are in all cases corrected with great accuracy by Hansen's Tables.'--The Report concludes with the following paragraph: 'With the inauguration of the new Equatoreal will terminate the entire change from the old state of the Observatory. There is not now a single person employed or instrument used in the Observatory which was there in Mr Pond's time, nor a single room in the Observatory which is used as it was used then. In every step of change, however, except this last, the ancient and traditional responsibilities of the Observatory have been most carefully considered: and, in the last, the subst.i.tution of a new instrument was so absolutely necessary, and the importance of tolerating no instrument except of a high cla.s.s was so obvious, that no other course was open to us. I can only trust that, while the use of the Equatoreal within legitimate limits may enlarge the utility and the reputation of the Observatory, it may never be permitted to interfere with that which has always been the staple and standard work here.'--Concerning the Sheepshanks Fund: There was much correspondence about settling the Gift till about Feb. 21st. I took part in the first examination for the Scholarship in October of this year, and took my place with the Trinity Seniority, as one of their number on this foundation, for some general business of the Fund.--With respect to the Correction of the Compa.s.s in Iron Ships: I sent Mr Ellis to Liverpool to see some practice there in the correction of the Compa.s.s. In September I urged Mr Rundell to make a voyage in the Great Eastern (just floated) for examination of her compa.s.ses, and lent him instruments: very valuable results were obtained. Mr Archibald Smith had edited Scoresby's Voyage in the Royal Charter, with an introduction very offensive to me: I replied fully in the Athenaeum of Nov. 7th.--The Sale of Gas Act: An Act of Parliament promoted by private members of the House of Commons had been pa.s.sed, without the knowledge or recollection of the Government. It imposed on the Government various duties about the preparation of Standards.

Suddenly, at the very expiration of the time allowed this came to the knowledge of Government. On Oct. 1st Lord Monteagle applied to me for a.s.sistance. On Oct. 15th and 22nd I wrote to Mr Hamilton, Secretary of the Treasury, and received authority to ask for the a.s.sistance of Prof. W.H. Miller.--I made an examination of Mr Ball's eyes (long-sighted and short-sighted I think).--In February I made an a.n.a.lysis of the Cambridge Tripos Examination, which I communicated to some Cambridge residents." In a letter on this subject to one of his Cambridge friends Airy gives his opinion as follows: "I have looked very carefully over the Examination Papers, and think them on the whole very bad. They are utterly perverted by the insane love of Problems, and by the foolish importance given to wholly useless parts of Algebraical Geometry. For the sake of these, every Physical Subject and every useful application of pure mathematics are cut down or not mentioned." This led to much discussion at Cambridge. In this year the Smith's Prizes were awarded to the 4th and 6th Wranglers.

Of private history: "On Apr. 29th Mrs Smith (my wife's mother) died at Brampton.--From July 4th to Aug. 2nd I was in France (Auvergne and the Vivarais) with my two eldest sons. Maclear travelled with us to Paris.--On Dec. 23rd I went to Playford."--Antiquities and historical questions connected with military movements had a very great attraction for Airy. On his return from the expedition in France above-mentioned, he engaged in considerable correspondence with military authorities regarding points connected with the battle of Toulouse. And in this year also he had much correspondence with the Duke of Northumberland concerning his Map of the Roman Wall, and the military points relating to the same.

1860

"In June Mr Main accepted the office of Radcliffe Observer at Oxford (Mr Johnson having died) and resigned the First a.s.sistancy at Greenwich: in October Mr Stone was appointed First a.s.sistant.--At an adjourned Meeting of the Visitors on June 18th there were very heavy discussions on Hansen's merits, and about the grant to him. Papers were read from Sir J. Lubbock, Babbage, South, Whewell, and me. Finally it was recommended to the Government to grant _1000_ to Hansen, which was paid to him.--In the Report to the Board of Visitors the following remark occurs: 'The apparent existence of a discordance between the results of Direct Observations and Reflection Observations (after the application of corrections for flexure, founded upon observations of the horizontal collimator wires) to an extent far greater than can be explained by any disturbance of the direction of gravity on the quicksilver by its distance from the vertical, or by the attraction of neighbouring ma.s.ses, perplexes me much.'--With respect to the discordance of dips of the dipping-needles, which for years past had been a source of great trouble and puzzle, the Report states that 'The dipping-needles are still a source of anxiety. The form which their anomalies appear to take is that of a special or peculiar value of the dip given by each separate needle. With one of the 9-inch needles, the result always differs about a quarter of a degree from that of the others. I can see nothing in its mechanical construction to explain this.--Reference is made to the spontaneous currents through the wires of telegraph companies, which are frequently violent and always occur at the times of magnetic storms, and the Report continues 'It may be worth considering whether it would ever be desirable to establish in two directions at right angles to each other (for instance, along the Brighton Railway and along the North Kent Railway) wires which would photographically register in the Royal Observatory the currents that pa.s.s in these directions, exhibiting their indications by photographic curves in close juxtaposition with the registers of the magnetic elements.'--In connection with the Reduction of the Greenwich Lunar Observations from 1831 to 1851, the Report states that 'The comparison of Hansen's Lunar Tables with the Greenwich Observations, which at the last Visitation had been completed for one year only, has now been finished for the twelve years 1847 to 1858. The results for the whole period agree entirely, in their general spirit, with those for the year 1852 cited in the last Report. The greatest difference between the merits of Burckhardt's and Hansen's Tables appears in the Meridional Longitudes 1855, when the proportion of the sum of squares of errors is as 31 (Burckhardt) to 2 (Hansen). The nearest approach is in the Altazimuth Lat.i.tudes 1854, when the proportion of the sum of squares of errors is as 12 (Burckhardt) to 5 (Hansen).'--A special Address to the Members of the Board of Visitors has reference to the proposals of M. Struve for (amongst other matters) the improved determination of the longitude of Valencia, and the galvanic determination of the extreme Eastern Station of the British triangles.--On Sept. 13th I circulated amongst the Visitors my Remarks on a Paper ent.i.tled 'On the Polar Distances of the Greenwich Transit-Circle, by A. Marth,' printed in the Astronomische Nachrichten; the Paper by Mr Marth was an elaborate attack on the Greenwich methods of observation, and my Remarks were a detailed refutation of his statements.--On Oct. 20th I made enquiry of Sabine as to the advantage of keeping up magnetic observations. On Oct. 22nd he wrote, avoiding my question in some measure, but saying that our instruments must be changed for such as those at Kew (his observatory): I replied, generally declining to act on that advice.--In March and April I was in correspondence with Mr Cowper (First Commissioner of Works, &c.) about the bells of the Westminster Clock; also about the smoky chimneys of the various apartments of the Palace. On Apr. 21st I made my Report on the clock and bells, 20 foolscap pages. I employed a professional musician to examine the tones of the bells.--In November I was writing my book on Probable Errors, &c.--I was engaged on the Tides of Kurrachee and Bombay.--The first examination of Navy telescopes was made for the Admiralty.

--Hoch's Paper on Aberration appeared in the Astronomische Nachrichten. This (with others) led to the construction of the water-telescope several years later.--In September I wrote in the Athenaeum against a notion of Sir H. James on the effect of an upheaval of a mountain in changing the Earth's axis. In October I had drawn up a list of days for a possible evagation of the Earth's poles: but apparently nothing was done upon them.

"In this year I was a good deal occupied for the Lighthouse Commission. On Feb. 21st Admiral Hamilton (chairman) applied to me for a.s.sistance. In April I went to Chance's Factory in Birmingham on this business. In May I made my report on the Start Lighthouse, after inspection with the Commission. In June, with my son Hubert, I visited the Whitby Lighthouses, and discovered a fault of a singular kind which most materially diminished their power. This discovery led to a general examination of lighthouses by the Trinity Board, to a modification of many, and to a general improvement of system. On June 25th I reported on the Lights at Calais, Cap de Valde, Grisnez, South Foreland, and North Foreland. In August I had been to the North Foreland again, and in September to Calais and the Cap d'Ailly. In October I went with my son Hubert to Aberdeen to see the Girdleness Lighthouse. On Nov. 10th I made a General Report.

"This was the year of the great total solar eclipse visible in Spain. At my representation, the Admiralty placed at my command the large steamship 'Himalaya' to carry about 60 astronomers, British and Foreign. Some were landed at Santander: I with many at Bilbao. The Eclipse was fairly well observed: I personally did not do my part well. The most important were Mr De La Rue's photographic operations.

At Greenwich I had arranged a very careful series of observations with the Great Equatoreal, which were fully carried out."

The eclipse expedition to Spain, shortly referred to above, was most interesting, not merely from the importance of the results obtained (and some of the parties were very fortunate in the weather) but from the character of the expedition. It was a wonderful combination of the astronomers of Europe, who were all received on board the 'Himalaya,' and were conveyed together to the coast of Spain. The polyglot of languages was most remarkable, but the utmost harmony and enthusiasm prevailed from first to last, and this had much to do with the general success of the expedition. Those who landed at Bilbao were received in the kindest and most hospitable manner by Mr C.B. Vignoles, the engineer-in-chief of the Bilbao and Tudela Railway, which was then under construction. This gentleman made arrangements for the conveyance of parties to points in the interior of the country which were judged suitable for the observation of the eclipse, and placed all the resources of his staff at the disposal of the expedition in the most liberal manner. The universal opinion was that very great difficulty would have been experienced without the active and generous a.s.sistance of Mr Vignoles. It is needless to say that the vote of thanks to Mr Vignoles, proposed by the Astronomer Royal during the return voyage, was pa.s.sed by acclamation and with a very sincere feeling of grat.i.tude: it was to the effect that 'without the great and liberal aid of Mr C.B. Vignoles, and the disinterested love of science evinced by him on this occasion, the success of the "Himalaya" eclipse expedition could not have been ensured.' There is a graphic and interesting account of the reception of the party at Bilbao given in the 'Life of C.B. Vignoles, F.R.S., Soldier and Civil Engineer,' by O.J. Vignoles, M.A.

Of private history: "On May 26th my venerable friend Arthur Biddell died. He had been in many respects more than a father to me: I cannot express how much I owed to him, especially in my youth.--From June 12th to 15th I visited the Whitby Lighthouses with my son Hubert.--From July 6th to 28th I was in Spain, on the 'Himalaya'

expedition, to observe the total eclipse: I was accompanied by my wife, my eldest son, and my eldest daughter.--From Oct. 5th to 18th I went with my son Hubert to Aberdeen to see the Girdleness Lighthouse, making lateral trips to c.u.mberland in going and returning.--On Dec. 21st I went to Playford."

1861

"In the Report to the Visitors there is great complaint of want of room. 'With increase of computations, we want more room for computers; with our greatly increased business of Chronometers and Time-Distribution, we are in want of a nearly separate series of rooms for the Time-Department: we want rooms for book-stores; and we require rooms for the photographic operations and the computations of the Magnetic Department.'--The Report gives a curious history of Dr Bradley's Observations, which in 1776 had been transferred to the University of Oxford, and proceeds thus: 'More lately, I applied (in the first instance through Lord Wrottesley) to the Vice-Chancellor, Dr Jeune, in reference to the possibility of transferring these ma.n.u.scripts to the Royal Observatory.... Finally, a decree for the transfer of the ma.n.u.script observations to the Royal Observatory, without any condition, was proposed to Convocation on May 2nd, and was pa.s.sed unanimously. And on May 7th my a.s.sistant, Mr Dunkin, was sent to Oxford to receive them. And thus, after a delay of very nearly a century, the great work of justice is at length completed, and the great gap in our ma.n.u.script observations is at length filled up.'--With reference to the Transit Circle, it had been remarked that the Collimators were slightly disturbed by the proximity of the gas-flames of their illuminators, and after various experiments as to the cause of it, the Report proceeds thus: 'To my great surprise, I found that the disturbance was entirely due to the radiation of the flame upon a very small corner (about 16 square inches) of the large and ma.s.sive stone on which the collimator is planted. The tin plates were subsequently shaped in such a manner as to protect the stone as well as the metal; and the disturbance has entirely ceased.'

--Regarding the large S.E. Equatoreal, the Report states that 'On the character of its object-gla.s.s I am now able to speak, first, from the examination of Mr Otto Struve, made in a favourable state of atmosphere; secondly, from the examinations of my a.s.sistants (I have not myself obtained a sight of a test-object on a night of very good definition). It appears to be of the highest order. The small star of gamma Andromedae is so far separated as to shew a broad dark s.p.a.ce between its components. Some blue colour is shewn about the bright planets.'--It is noted in the Report that 'The Equatoreal observations of the Solar Eclipse are completely reduced; and the results are valuable. It appears from them that the error in right ascension of Burckhardt's Lunar Tables at the time of the eclipse amounted to about 38"; while that of Hansen's (ultimately adopted by Mr Hind for the calculation of the eclipse) did not exceed 3".'--With regard to Chronometers it is stated that 'By use of the Chronometer Oven, to which I have formerly alluded, we have been able to give great attention to the compensation. I have reason to think that we are producing a most beneficial effect on the manufacture and adjustment of chronometers in general.'--With regard to the Cape of Good Hope Observatory and Survey, the Admiralty enquire of me when the Survey work will be completed, and I enquire of Maclear 'How is the printing of your Survey Work?' In 1862 I began to press it strongly, and in 1863 very strongly.--I introduced a method (constantly pursued since that time at the Royal Observatory) for computing interpolations without changes of sign.--I had correspondence with Herschel and Faraday, on the possible effect of the Sun's radiant heat on the sea, as explaining the curve of diurnal magnetic inequality. (That diurnal inequality was inferred from the magnetic reductions 1848-1857, which were terminated in 1860.)--Regarding the proposal of hourly time-signals on the Start Point, I consulted telegraph engineers upon the practical points, and on Dec. 21st I proposed a formal scheme, in complete detail. (The matter has been repeatedly brought before the Admiralty, but has been uniformly rejected.)--I was engaged on the question of the bad ocular vision of two or three persons.--The British a.s.sociation Meeting was held at Manchester: I was President of Section A. I gave a Lecture on the Eclipse of 1860 to an enormous attendance in the Free Trade Hall." The following record of the Lecture is extracted from Dr E.J. Routh's Obituary Notice of Airy written for the Proceedings of the Royal Society. "At the meeting of the British a.s.sociation at Manchester in 1861, Mr Airy delivered a Lecture on the Solar Eclipse of 1860 to an a.s.sembly of perhaps 3000 persons. The writer remembers the great Free Trade Hall crowded to excess with an immense audience whose attention and interest, notwithstanding a weak voice, he was able to retain to the very end of the lecture....The charm of Professor Airy's lectures lay in the clearness of his explanations. The subjects also of his lectures were generally those to which his attention had been turned by other causes, so that he had much that was new to tell. His manner was slightly hesitating, and he used frequent repet.i.tions, which perhaps were necessary from the newness of the ideas. As the lecturer proceeded, his hearers forgot these imperfections and found their whole attention rivetted to the subject matter."

Of private history: "On Jan. 2nd there was a most remarkable crystallization of the ice on the flooded meadows at Playford: the frost was very severe.--From June 20th to Aug. 1st I was at the Grange near Keswick (where I hired a house) with my wife and most of my family.--From Nov. 5th to 14th I was on an expedition in the South of Scotland with my son Wilfrid: we walked with our knapsacks by the Roman Road across the Cheviots to Jedburgh.--On Dec. 21st I went to Playford."

1862

"The Report to the Board of Visitors states that 'A new range of wooden buildings (the Magnetic Offices) is in progress at the S.S.E. extremity of the Magnetic Ground. It will include seven rooms.'--Also 'I took this opportunity (the relaying of the water-main) of establishing two powerful fire-plugs (one in the Front Court, and one in the Magnetic Ground); a stock of fire-hose adapted to the "Brigade-Screw" having been previously secured in the Observatory.'--'Two wires, intended for the examination of spontaneous earth-currents, have been carried from the Magnetic Observatory to the Railway Station in the town of Greenwich. From this point one wire is to be led to a point in the neighbourhood of Croydon, the other to a point in the neighbourhood of Dartford. Each wire is to be connected at its two extremities with the Earth. The angle included between the general directions of these two lines is nearly a right angle.'--'The Kew unifilar magnetometer, adapted to the determination of the horizontal part of terrestrial magnetic force in absolute measure, was mounted in the summer of 1861; and till 1862 February, occasional observations (14 in all) were taken simultaneously with the old and with the new instrument. The comparison of results shewed a steady but very small difference, not greater probably than may correspond to the omission of the inverse seventh powers of distance in the theoretical investigation; proving that the old instrument had been quite efficient for its purpose.'--Great efforts had been made to deduce a law from the Diurnal Inequalities in Declination and Horizontal Force, as shewn by the Magnetic observations; but without success: the Report states that 'The results are most amazing, for the variation in magnitude as well as in law. What cosmical change can be indicated by them is entirely beyond my power of conjecture.'--'I have alluded, in the two last Reports, to the steps necessary, on the English side, for completing the great Arc of Parallel from Valencia to the Volga. The Russian portion of the work is far advanced, and will be finished (it is understood) in the coming summer. It appeared to me therefore that the repet.i.tion of the measure of astronomical longitude between Greenwich and Valencia could be no longer delayed. Two a.s.sistants of the Royal Observatory (Mr Dunkin and Mr Criswick) will at once proceed to Valencia, for the determination of local time and the management of galvanic signals.'--'I now ask leave to press the subject of Hourly Time Signals at the Start Point on the attention of the Board, and to submit the advantage of their addressing the Board of Admiralty upon it. The great majority of outward-bound ships pa.s.s within sight of the Start, and, if an hourly signal were exhibited, would have the means of regulating their chronometers at a most critical part of their voyage. The plan of the entire system of operations is completely arranged. The estimated expense of outfit is _2017_, and the estimated annual expense is _326_; both liable to some uncertainty, but sufficiently exact to shew that the outlay is inconsiderable in comparison with the advantages which might be expected from it. I know no direction of the powers of the Observatory which would tend so energetically to carry out the great object of its establishment, viz. "the finding out the so much desired Longitude at Sea."'--The attention of the Visitors is strongly drawn to the pressure on the strength of the Observatory caused by the observation of the numerous small planets, and the paragraph concludes thus: 'I shall, however, again endeavour to effect a part.i.tion of this labour with some other Observatory.'--A small fire having occurred in the Magnetic Observatory, a new building of zinc, for the operation of naphthalizing the illuminating gas, is in preparation, external to the Observatory: and thus one of the possible sources of accidental fire will be removed.--Miss Sheepshanks added, through me, _2000_ to her former gift: I transferred it, I believe, to the Master and Seniors of Trinity College."--In this year Airy contributed to the Royal Society two Papers, one "On the Magnetic properties of Hot-Rolled and Cold-Rolled Malleable Iron," the other "On the Strains in the Interior of Beams." He gave evidence before the Select Committee on Weights and Measures, and also before the Public Schools Commission.