1871
"In April 1870 the Assistants had applied for an increase of salary, a request which I had urged strongly upon the Admiralty. On Jan. 27 of this year the Admiralty answered that, on account of Mr Childers's illness, the consideration must be deferred to next year! The Assistants wrote bitterly to me: and with my sanction they wrote to the First Lord. On Jan. 31st I requested an interview with Mr Baxter (secretary of the Admiralty), and saw him on Feb. 3rd, when I obtained his consent to an addition of£530. There was still a difficulty with the Treasury, but on June 27th the liberal scale was allowed.—Experiments made by Mr Stone shew clearly that a local elevation, like that of the Royal Observatory on the hill of Greenwich Park, has no tendency to diminish the effect of railway tremors.—The correction for level error in the Transit Circle having become inconveniently large, a sheet of very thin paper, 1/270 inch in thickness, was placed under the eastern Y, which was raised from its bed for the purpose. The mean annual value of the level-error appears to be now sensibly zero.—As the siege and war operations in Paris seriously interfered with the observations of small planets made at the Paris Observatory, observations of them were continued at Greenwich throughout each entire lunation during the investment of the city.—The new Water-Telescope has been got into working order, and performs most satisfactorily. Observations of gamma Draconis have been made with it, when the star passed between 20h and 17h, with some observations for adjustment at a still more advanced time. As the astronomical latitude of the place of observation is not known, the bearing of these observations on the question of aberration cannot be certainly pronounced until the autumn observations shall have been made; but supposing the geodetic latitude to be accordant with the astronomical latitude, the result for aberration appears to be sensibly the same as with ordinary telescopes.—Several years since, I prepared a barometer, by which the barometric fluctuations were enlarged, for the information of the public; its indications are exhibited on the wall, near to the entrance gate of the Observatory. A card is now also exhibited, in a glass case near the public barometer, giving the highest and lowest readings of the thermometer in the preceding twenty-four hours.—Those who have given attention to the history of Terrestrial Magnetism are aware that Halley's Magnetic Chart is very frequently cited; but I could not learn that any person, at least in modern times, had seen it. At last I discovered a copy in the library of the British Museum, and have been allowed to take copies by photolithography. These are appended to the Magnetical and Meteorological Volume for 1869.—The trials and certificates of hand-telescopes for the use of the Royal Navy have lately been so frequent that they almost become a regular part of the work of the Observatory. I may state here that by availing myself of a theory of eyepieces which I published long since in the Cambridge Transactions, I have been able to effect a considerable improvement in the telescopes furnished to the Admiralty.—The occurrence of the Total Eclipse of the Sun in December last has brought much labour upon the Observatory. As regards the assistants and computers, the actual observation on a complicated plan with the Great Equatoreal (a plan for which few equatoreals are sufficiently steady, but which when properly carried out gives a most complete solution of the geometrical problem) has required, in observation and in computation, a large expenditure of time.—My preparations for the Transit of Venus have respect only to eye-observation of contact of limbs. With all the liabilities and defects to which it is subject, this method possesses the inestimable advantage of placing no reliance on instrumental scales. I hope that the error of observation may not exceed four seconds of time, corresponding to about 0.13" of arc. I shall be very glad to see, in a detailed form, a plan for making the proper measures by heliometric or photographic apparatus; and should take great interest in combining these with the eye-observations, if my selected stations can be made available. But my present impression is one of doubt on the certainty of equality of parts in the scale employed. An error depending on this cause could not be diminished by any repetition of observations."—After referring to the desirability of vigorously prosecuting the Meteorological Reductions (already begun) and of discussing the Magnetic Observations, the Report concludes thus: "There is another consideration which very often presents itself to my mind; the waste of labour in the repetition of observations at different observatories….. I think that this consideration ought not to be put out of sight in planning the courses of different Observatories."—In this year De Launay's Lunar Theory was published. This valuable work was of great service to Airy in the preparation of the Numerical Lunar Theory, which he subsequently undertook.—In the latter part of this year Airy was elected President of the Royal Society, and held the office during 1872 and 1873. At this time he was much pressed with work, and could ill afford to take up additional duties, as the following quotation from a letter to one of his friends shews: "The election to the Presidency of R.S. is flattering, and has brought to me the friendly remembrances of many persons; but in its material and laborious connections, I could well have dispensed with it, and should have done so but for the respectful way in which it was pressed on me."
Of private history: There was the usual winter visit to Playford.—InApril he made a short trip to Cornwall with his daughter Annot.—InJune he was appointed a Companion of the Bath, and was presented atCourt on his appointment.—Mrs Airy was staying with her daughter, MrsRouth, at Hunstanton, during June, her state of health being somewhatimproved.—From August 1st to 28th he was chiefly in Cumberland, atBarrow House, and at Grange, Borrowdale, where his son Osmund wasstaying for a holiday.
1872
"From the Report to the Board of Visitors it appears that 'The Normal Siderial Clock for giving sidereal time by galvanic communication to the Astronomical Observatory was established in the Magnetic Basement in 1871, June; that locality being adapted for it on account of the uniformity of temperature, the daily changed of temperature rarely exceeding 1° Fahrenheit. Its escapement is one which I suggested many years ago in the Cambridge Transactions; a detached escapement, very closely analogous to the ordinary chronometer escapement, the pendulum receiving an impulse only at alternate vibrations…. The steadiness of rate is very far superior to any that we have previously attained.'—The aspect of railway enterprise is at present favourable to the Park and to the Observatory. The South-Eastern Railway Company has made an arrangement with the Metropolitan Board of Works for shifting the course of the great Southern Outfall Sewer. This enables the Company to trace a new line for the railway, passing on the north side of London Street, at such a distance from the Observatory as to remove all cause of alarm. I understand that the Bill, which was unopposed, has passed the Committee of the House of Commons. I trust that the contest, which has lasted thirty-seven years, is now terminated.—The observations of 7 Draconis with the Water-Telescope, made in the autumn of 1871, and the spring of 1872, are reduced, the latter only in their first steps…. Using the values of the level scales as determined by Mr Simms (which I have no reason to believe to be inaccurate) the spring and autumn observations of 1871 absolutely negative the idea of any effect being produced on the constant of aberration by the amount of refracting medium traversed by the light.—The great Aurora of 1872 Feb. 4 was well observed. On this occasion the term Borealis would have been a misnomer, for the phenomenon began in the South and was most conspicuous in the South. Three times in the evening it exhibited that umbrella-like appearance which has been called (perhaps inaccurately) a corona. I have very carefully compared its momentary phenomena with the corresponding movements of the magnetometers. In some of the most critical times, the comparison fails on account of the violent movements and consequent faint traces of the magnetometers. I have not been able to connect the phases of aurora and those of magnetic disturbance very distinctly.—The Report contains a detailed account of the heavy preparations for the observation of the Transit of Venus 1874, including the portable buildings for the instruments, the instruments themselves (being a transit-instrument, an altazimuth, and an equatoreal, for each station), and first class and second-class clocks, all sufficient for the equipment of 5 stations, and continues thus: I was made aware of the assent of the Government to the wish of the Board of Visitors, as expressed at their last meeting, that provision should be made for the application of photography to the observation of the Transit of Venus. It is unnecessary for me to remark that our hope of success is founded entirely on our confidence in Mr De La Rue. Under his direction, Mr Dallmeyer has advanced far in the preparation of five photoheliographs…. The subject is recognized by many astronomers as not wholly free from difficulties, but it is generally believed that these difficulties may be overcome, and Mr De La Rue is giving careful attention to the most important of them.—I take this opportunity of reporting to the Board that the Observatory was honoured by a visit of His Majesty the Emperor of Brazil, who minutely examined every part."—After referring to various subjects which in his opinion might be usefully pursued systematically at the Observatory, the Report proceeds thus: "'The character of the Observatory would be somewhat changed by this innovation, but not, as I imagine, in a direction to which any objection can be made. It would become, pro tanto, a physical observatory; and possibly in time its operations might be extended still further in a physical direction.'—The consideration of possible changes in the future of the Observatory leads me to the recollection of actual changes in the past. In my Annual Reports to the Visitors I have endeavoured to chronicle these; but still there will be many circumstances which at present are known only to myself, but which ought not to be beyond the reach of history. I have therefore lately employed some time in drawing up a series of skeleton annals of the Observatory (which unavoidably partakes in some measure of the form of biography), and have carried it through the critical period, 1836-1851. If I should command sufficient leisure to bring it down to 1861, I think that I might then very well stop." (The skeleton annals here referred to are undoubtedly the manuscript notes which form the basis of the present biography. Ed.)—"On Feb. 23rd in this year I first (privately) formed the notion of preparing a numerical Lunar Theory by substituting Delaunay's numbers in the proper Equations and seeing what would come of it."
Of private history: There was the usual visit to Playford—in this year later than usual—from Feb. 4th to Mar. 4th. The letters written during this visit are, as usual, full of freshness and delight at finding himself in his favourite country village.—On June 5th he went to Barrow House, near Keswick, to be present at the marriage of his second son Hubert to Miss S. C. Langton, daughter of Z. Langton Esq., of Barrow House.—After the wedding he made a trip through the Trossachs district of Scotland with his daughter Annot, and returned to Greenwich on June 17th.
On the 26th June 1872 Airy was appointed a Knight Commander of the Most Honourable Order of the Bath: he was knighted by the Queen at Osborne on the 30th of July. In the course of his official career he had three times been offered Knighthood, and had each time declined it: but it seemed now as if his scruples on the subject were removed, and it is probable that he felt gratified by the public recognition of his services. Of course the occasion produced many letters of congratulation from his friends: to one of these he replied as follows: "The real charm of these public compliments seems to be, that they excite the sympathies and elicit the kind expressions of private friends or of official superiors as well as subordinates. In every way I have derived pleasure from these." From the Assistants of the Royal Observatory he received a hearty letter of congratulation containing the following paragraph. "Our position has naturally given us peculiar opportunities for perceiving the high and broad purposes which have characterized your many and great undertakings, and of witnessing the untiring zeal and self-denial with which they have been pursued."
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On the 18th of March 1872 Airy was nominated a Foreign Associate of the Institut de France, to fill the place vacant by the death of Sir John Herschel. The following letter of acknowledgment shews how much he was gratified by this high scientific honour:
ROYAL OBSERVATORY, GREENWICH,1872, March 23.
ÀMessieurs Messieurs ELIE DE BEAUMONT,etJ.B. DUMAS,Secrétaires perpetuels de l'Académie des Sciences, Institut de France.
I am honoured with your letter of March 18, communicating to me my nomination by the Academy of Sciences to the place rendered vacant in the class of Foreign Associates of the Academy by the decease of Sir John Herschel, and enclosing Copy of the Decree of the President of the French Republic approving the Election.
It is almost unnecessary for me to attempt to express to you the pride and gratification with which I receive this announcement. By universal consent, the title ofAssocié Etranger de l'Académie des Sciencesis recognised as the highest distinction to which any man of science can aspire; and I can scarcely imagine that, unless by the flattering interpretation of my friends in the Academy, I am entitled to bear it. But in any case, I am delighted to feel that the bands of friendship are drawn closer between myself and the distinguished body whom, partly by personal intercourse, partly by correspondence, and in every instance by reputation, I have known so long.
I beg that you will convey to the Academy my long-felt esteem for that body in its scientific capacity, and my deep recognition of its friendship to me and of the honor which it has conferred on me in the late election.
I have the honor to beGentlemen,Your very faithful servant,G.B. AIRY.
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On the 20th November 1872 Airy was nominated a Grand Cross in the Imperial Order of the Rose of Brazil: the insignia of the Order were accompanied by an autograph letter from the Emperor of Brazil, of which the following is a transcript.
Vous êtes un des doyens de la science, et le Président de l'illustre Société, qui a eu la bienveillance d'inscrire mon nom parmi ceux de ses associés. La manière, dont vous m'avez fait les honneurs de votre Observatoire m'a imposé aussi l'agréable devoir d'indiquer votre nom à l'empereur de Brésil pour un témoignage de haute estime, dont je suis fort heureux de vous faire part personellement, en vous envoyant les décorations que vous garderez, an moins, comme un souvenir de ma visite à Greenwich.
J'espère que vous m'informerez, quand il vous sera aisé, des travaux de votre observatoire, et surtout de ce que l'on aura fait pour l'observation du passage de Vénus et la détermination exacte de la passage.
J'ai reçu déjà lesProceedings de la Royal Societylesquels m'intéressent vivement.
Je voudrais vous écrire dans votre langue, mais, comme je n'en ai pas l'habitude, j'ai craigné de ne pas vous exprimer tout-à-fait les sentiments de
Votre affectionné,D. PEDRO D'ALCANTARA.
RIO,22 Octobre, 1872.
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Airy's reply was as follows:
ROYAL OBSERVATORY, GREENWICH,1872, November 26.
I am honoured with your Imperial Majesty's autograph letter of October 22 informing me that, on considering the attention which the Royal Society of London had been able to offer to your Majesty, as well as the explanation of the various parts of the establishment of this Observatory which I had the honor and the high gratification to communicate, You had been pleased to place my name in the Imperial Order of the Rose, and to present to me the Decorations of Grand Cross of that Order.
With pride I receive this proof of Your Majesty's recollection of your visit to the scientific institutions of Great Britain.
The Diploma of the appointment to the Order of the Rose, under theImperial Sign Manual, together with the Decorations of the Order, havebeen transmitted to me by his Excellency Don Pereira de Andrada, YourMajesty's Representative at the British Court.
Your Majesty has been pleased to advert to the approaching Transit of Venus, on the preparations for which you found me engaged. It is unfortunate that the Transit of 1874 will not be visible at Rio de Janeiro. For that of 1882, Rio will be a favourable position, and we reckon on the observations to be made there. Your Majesty may be assured that I shall loyally bear in mind your desire to be informed of any remarkable enterprise of this Observatory, or of any principal step in the preparations for the Transit of Venus and of its results.
I have the honor to beSire,Your Imperial Majesty's very faithful servant,G.B. AIRY.
To His MajestyThe Emperor of Brazil.
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Airy's old friend, Adam Sedgwick, was now very aged and infirm, but his spirit was still vigorous, and he was warm-hearted as ever. The following letter from him (probably the last of their long correspondence) was written in this year, and appears characteristic:
TRINITY COLLEGE, CAMBRIDGE,May 10, 1872.
I have received your card of invitation for the 1st of June, and with great joy should I count upon that day if I thought that I should be able to accept your invitation: but alas I have no hope of the kind, for that humiliating malady which now has fastened upon me for a full year and a half has not let go its hold, nor is it likely to do so. A man who is journeying in the 88th year of his pilgrimage is not likely to throw off such a chronic malady. Indeed were I well enough to come I am deaf as a post and half blind, and if I were with you I should only be able to play dummy. Several years have passed away since I was last at your Visitation and I had great joy in seeing Mrs Airy and some lady friends at the Observatory, but I could not then attend the dinner. At that Meeting were many faces that I knew, but strangely altered by the rude handling of old Time, and there were many new faces which I had never seen before at a Royal Society Meeting; but worse than all, all the old faces were away. In vain I looked round for Wollaston, Davy, Davies Gilbert, Barrow, Troughton, &c. &c.; and the merry companion Admiral Smyth was also away, so that my last visit had its sorrowful side. But why should I bother you with these old man's mopings.
I send an old man's blessing and an old man's love to all the members of your family; especially to Mrs Airy, the oldest and dearest of my lady friends.
I remain, my dear Airy,Your true-hearted old friend,hisADAM X SEDGWICK.mark
P.S. Shall I ever again gaze with wonder and delight from the great window of your Observatory.
The body of the above letter is in the handwriting of an amanuensis, but the signature and Postscript are in Sedgwick's handwriting. (Ed.)
* * * * *
1873
"Chronographic registration having been established at the Paris Observatory, Mr Hilgard, principal officer of the American Coast Survey, has made use of it for determining the longitude of Harvard from Greenwich, through Paris, Brest, and St Pierre. For this purpose Mr Hilgard's Transit Instrument was planted in the Magnetic Court. I understand that the result does not sensibly differ from that obtained by Mr Gould, through Valentia and Newfoundland.—It was known to the scientific world that several of the original thermometers, constructed by Mr Sheepshanks (in the course of his preparation of the National Standard of Length) by independent calibration of the bores, and independent determination of the freezing and boiling points on arbitrary graduations, were still preserved at the Royal Observatory. It was lately stated to me by M. Tresca, the principal officer of the International Metrical Commission, that, in the late unhappy war in Paris, the French original thermometers were destroyed; and M. Tresca requested that, if possible, some of the original thermometers made by Mr Sheepshanks might be appropriated to the use of the International Commission. I have therefore transferred to M. Tresca the three thermometers A.6, S.1, S.2, with the documentary information relating to them, which was found in Mr Sheepshanks's papers; retaining six thermometers of the same class in the Royal Observatory.—The Sidereal Standard Clock continues to give great satisfaction. I am considering (with the aid of Mr Buckney, of the firm of E. Dent and Co.) an arrangement for barometric correction, founded on the principle of action on the pendulum by means of a magnet which can be raised or lowered by the agency of a large barometer.—The Altazimuth has received some important alterations. An examination of the results of observations had made me dissatisfied with the bearings of the horizontal pivots in their Y's. Mr Simms, at my request, changed the bearings in Y's for bearing in segments of circles, a construction which has worked admirably well in the pivots of the Transit Circle." (And in various other respects the instrument appears to have received a thorough overhauling. Ed.)—"With the consent of the Royal Society and of the Kew Committee, the Kew Heliograph has been planted in the new dome looking over the South Ground. It is not yet finally adjusted.—Some magnetic observations in the Britannia and Conway tubular bridges were made last autumn. For this purpose I detached an Assistant (Mr Carpenter), who was aided by Capt. Tupman, R.M.A.; in other respects the enterprise was private and at private expense.—The rates of the first six chronometers (in the annual trials) are published, in a form which appears most likely to lead to examination of the causes that influence their merits or demerits. This report is extensively distributed to British and Foreign horologists and instrument-makers. All these artists appear to entertain the conviction that the careful comparisons made at this Observatory, and the orderly form of their publication, have contributed powerfully to the improvement of chronometers.—Very lately, application has been made to me, through the Board of Trade, for plans and other information regarding time-signal-balls, to assist in guiding the authorities of the German Empire in the establishment of time signals at various ports of that State. In other foreign countries the system is extending, and is referred to Greenwich as its origin.—The arrangements and preparations for the observation of the Transit of Venus occupied much attention. With regard to the photoheliographs it is proposed to make trial of a plan proposed by M. Janssen, for numerous photographs of Venus when very near to the Sun's limb. On Apr. 26th the engaging of photographic teachers was sanctioned. Observers were selected and engaged. A working model of the Transit was prepared, and the use of De La Rue's Scale was practised. There was some hostile criticism of the stations selected for the observation of the Transit, which necessitated a formal reply.—Reference is made to the increase of facilities for making magnetical and meteorological observations. The inevitable result of it is, that observations are produced in numbers so great that complete reduction becomes almost impossible. The labour of reduction is very great, and it is concluded that, of the enormous number of meteorological observations now made at numerous observatories, very few can ever possess the smallest utility.—Referring to my Numerical Lunar Theory: on June 30th, 1873, a theory was formed, nearly but not perfectly complete. Numerical development of powers of a÷r and r÷a. Factors of corrections to Delaunay first attempted, but entirely in numerical form."—In March of this year Airy was consulted by Mr W.H. Barlow, C.E., and Mr Thomas Bouch (the Engineer of the Tay Bridge, which was blown down in 1879, and of a proposed scheme for a Forth Bridge in 1873) on the subject of the wind pressure, &c., that should be allowed for in the construction of the bridge. Airy's report on this question is dated 1873, Apr. 9th: it was subsequently much referred to at the Official Enquiry into the causes of the failure of the Tay Bridge.—At the end of this year Airy resigned the Presidency of the Royal Society. In his Address to the Society on Dec. 1st he stated his reasons in full, as follows: "the severity of official duties, which seem to increase, while vigour to discharge them does not increase; and the distance of my residence…. Another cause is a difficulty of hearing, which unfits me for effective action as Chairman of Council."
Of private history: There was the usual visit to Playford in January: also a short visit in May: and a third visit at Christmas.—There was a short run in June, of about a week, to Coniston, with one of his daughters.—And there was a trip to Weymouth, &c., for about 10 days, with one of his daughters, in the beginning of August—On his return from the last-mentioned trip, Airy found a letter from the Secretary of the Swedish Legation, enclosing the Warrant under the Royal Sign Manual of His Majesty (Oscar), the King of Sweden and Norway, by which he was nominated as a First Class Commander of the Order of the North Star, and accompanying the Decorations of that Order.
1874
"In this year Mr Glaisher resigned his appointment: I placed his Department (Magnetical and Meteorological) under Mr Ellis.—A balance of peculiar construction has been made by Mr Oertling, from my instructions, and fixed near the public barometer at the Entrance Gate. This instrument enables the public to test any ordinary pound weight, shewing on a scale the number of grains by which it is too heavy or too light.—Fresh counterpoises have been attached to the Great Equatoreal to balance the additional weight of the new Spectroscope, which was finally received from Mr Browning's hands on May 2nd of the present year. The Spectroscope is specifically adapted to sweeping round the Sun's limb, with a view to mapping out the prominences, and is also available for work on Stars and Nebulae, the dispersive power being very readily varied. An induction-coil, capable of giving a six-inch spark, has been made for this instrument by Mr Browning.—Some new classes of reductions of the meteorological observations from 1848 to 1868 have been undertaken and completed in the past year. The general state of this work is as follows: The diurnal changes of the dry-bulb thermometer, as depending on the month, on the temperature waves, on the barometric waves, on the overcast and cloudless states of the sky, and on the direction of the wind, have been computed and examined for the whole period; and the exhibition of the results is ready for press. The similar reductions for the wet-bulb thermometer are rapidly approaching completion. —Regarding the preparations for the Transit of Venus Expeditions. Originally five stations were selected and fully equipped with equatoreals, transits, altazimuths, photoheliographs, and clocks; but I have since thought it desirable to supplement these by two branch stations in the Sandwich Islands and one in Kerguelen's Island; and the additional instruments thus required have been borrowed from various sources, so that there is now an abundant supply of instrumental means…. There will thus be available for observation of the Transit of Venus 23 telescopes, nine of which will be provided with double-image-micrometers; and five photoheliographs; and for determination of local time, and latitude and longitude, there will be nine transits and six altazimuths…. All the observers have undergone a course of training in photography; first, under a professional photographer, Mr Reynolds, and subsequently under Capt. Abney, R.E., whose new dry-plate process is to be adopted at all the British Stations…. A Janssen slide, capable of taking 50 photographs of Venus and the neighbouring part of the Sun's limb at intervals of one second, has been made by Mr Dallmeyer for each of the five photoheliographs."—Attached to the Report to the Visitors is a copy of the Instructions to Observers engaged in the Transit of Venus Expeditions, prepared with great care and in remarkable detail.—"In the past spring I published in the Monthly Notices of the Royal Astronomical Society a statement of the fundamental points in a new treatment of the Lunar Theory, by which, availing myself of all that has been done in the best algebraical investigations of that theory, I trust to be able by numerical operations only to give greater accuracy to final results. Considerable progress has been made in the extensive numerical developments, the work being done, at my private expense, entirely by a junior computer; and I hope, at any rate, to put it in such a state that there will be no liability to its entire loss. When this was reported to the Board of Visitors, it was resolved on the motion of Prof. Stokes, that this work, as a public expense, ought to be borne by the Government; and this was forwarded to the Admiralty. On June 24th I wrote to the Secretary of the Admiralty, asking for£100for the present year, which after the usual enquiries and explanations was sanctioned on Aug. 29th."
Of private history: There were short visits to Playford in January, June, and October, but only for a few days in each case.—In March there was a run of two or three days to Newnham (on the Severn) to see the Bore on the Severn, and to Malvern.—In July he went to Newcastle to observe with Mr Newall's great telescope, but the weather was unfavourable: he then went on to Barrow House near Keswick, and spent a few days there, with excursions among the mountains.—On Aug. 13th he went with his daughter Christabel to the Isle of Arran, and then by Glasgow to the Trosachs, where he made several excursions to verify the localities mentioned in the "Lady of the Lake."—While in Scotland he heard of the death of his brother, the Rev. William Airy, and travelled to Keysoe in Bedfordshire to attend the funeral; and returned to Greenwich on Aug. 24th.
1875
"In October of this year I wrote to the Admiralty that I had grounds for asking for an increase of my salary: because the pension which had been settled on my wife, and which I had practically recognized as part of my salary, had been terminated by her death; so that my salary now stood lower by£200than that of the Director of Studies of the Royal Naval College. The Admiralty reply favourably, and on Nov. 27th the Treasury raise my salary to£1,200.—For the service of the Clock Movement of the Great Equatoreal, a water-cistern has been established in the highest part of the Ball-Turret, the necessity for which arose from the following circumstance: The Water Clock was supplied by a small pipe, about 80 feet in length, connected with the 3-inch Observatory main (which passes through the Park), at a distance of about 250 feet from any other branch pipe. In spite of this distance I have seen that, on stopping the water-tap in the Battery-Basement under the North-East Turret, the pressure in the gauge of the Water Clock has been instantly increased by more than 40 lbs. per square inch. The consequent derangement of the Water Clock in its now incessant daily use became intolerable. Since the independent supply was provided, its performance has been most satisfactory.—With the Spectroscope the solar prominences have been mapped on 28 days only; but the weather of the past winter was exceptionally unfavourable for this class of observation. After mapping the prominences, as seen on the C line, the other lines, especially F and b, have been regularly examined, whenever practicable. Great care has been taken in determining the position, angle, and heights of the prominences in all cases. The spectrum of Coggia's Comet was examined at every available opportunity last July, and compared directly with that of carbon dioxide, the bands of the two spectra being sensibly coincident. Fifty-four measures of the displacement of lines in the spectra of 10 stars, as compared with the corresponding lines in the spectra of terrestrial elements (chiefly hydrogen), have been made, but some of these appear to be affected by a constant error depending on faulty adjustment of the Spectroscope.—Photographs of the Sun have been taken with the Kew Photoheliograph on 186 days; and of these 377 have been selected for preservation. The Moon, Jupiter, Saturn, and several stars (including the Pleiades and some double stars) have been photographed with the Great Equatoreal, with fairly satisfactory results, though further practice is required in this class of work.—I would mention a supplemental mechanism which I have myself introduced into some chronometers. I have long remarked that, in ordinary good chronometers, the freedom from irregularities depending on mechanical causes is most remarkable; but that, after all the efforts of the most judicious makers, there is in nearly every case a perceptible defect of thermal compensation. There is great difficulty in correcting the residual fault, not only because an inconceivably small movement of the weights on the balance-curve is required, but also because it endangers the equilibrium of the balance. The mechanism adopted to remedy the defect is described in a Paper in the Horological Journal of July 1875 by Mr W. Ellis, and has received the approval of some able chronometer-makers.—With respect to the Transit of Venus Expeditions: The parties from Egypt and Rodriguez are returned. I am in continual expectation of the arrival of the other parties. I believe the eye-observations and the ordinary photographs to be quite successful; I doubt the advantage of the Janssen; one of the double-image-micrometers seems to have failed; and the Zenith-telescope gives some trouble. At three stations at Rodriguez, and three at Kerguelen, the observations appear to have been most successful. At the Sandwich Islands, two of the stations appear to have been perfectly successful (except that I fear that the Janssen has failed), and a rich series of lunar observations for longitude is obtained. At New Zealand, I grieve to say, the observations were totally lost, entirely in consequence of bad weather. There has been little annoyance from the dreaded 'black drop.' Greater inconvenience and doubt have been caused by the unexpected luminous ring round Venus.—With regard to the progress of my proposed New Lunar Theory: Three computers are now steadily employed on the work. It will be remembered that the detail and mass of this work are purely numerical; every numerical coefficient being accompanied with a symbolical correction whose value will sometimes depend on the time, but in every case is ultimately to be obtained in a numerical form. Of these coefficients, extracted (for convenience) from Delaunay's results, there are 100 for parallax, 182 for longitude, 142 for latitude; the arguments being preserved in the usual form."—After reviewing the changes that had taken place at the Observatory during the past forty years, the Report to the Board of Visitors concludes thus: "I much desire to see the system of time-signals extended, by clocks or daily signals, to various parts of our great cities and our dockyards, and above all by hourly signals on the Start Point, which I believe would be the greatest of all benefits to nautical chronometry. Should any extension of our scientific work ever be contemplated, I would remark that the Observatory is not the place for new physical investigations. It is well adapted for following out any which, originating with private investigators, have been reduced to laws susceptible of verification by daily observation. The National Observatory will, I trust, always remain on the site where it was first planted, and which early acquired the name of 'Flamsteed Hill.' There are some inconveniences in the position, arising principally from the limited extent of the hill, but they are, in my opinion, very far overbalanced by its advantages."—In a letter on the subject of the Smith's Prizes Examination at Cambridge, which was always a matter of the greatest interest to him, Airy renewed his objections to the preponderance in the Papers of a class of Pure Mathematics, which he considered was never likely under any circumstances to give the slightest assistance to Physics. And, as before, these remarks called forth a rejoinder from Prof. Cayley, who was responsible for many of the questions of the class referred to.—In this year Airy completed his "Notes on the Earlier Hebrew Scriptures," which were shortly afterwards published as a book by Messrs Longmans, Green, & Co. In his letter to the publishers introducing the subject, he says, "For many years past I have at times put together a few sentences explanatory as I conceive of the geographical and historical circumstances connected with the principal events recorded in the Hebrew Scriptures. The view which I take is free, but I trust not irreverent. They terminate with a brief review of Colenso's great work. The collection now amounts to a small book." From the references already given in previous years to his Papers and correspondence on the geography of Exodus, his correspondence with Colenso, &c. &c., it will be seen that he took a great interest in the early history of the Israelites.—On August 10th, 1875, Airy celebrated the Bicentenary of the Royal Observatory by a dinner in the Octagon Room, which was attended by the Presidents of the Royal Society and the R. Astr. Society, and by a large number of Scientific gentlemen interested in Astronomy.—In February he was revising his Treatise on "Probabilities."
Of private history: up to Jan. 16th Airy was at Playford as usual.—For about a week in April he was in the Isle of Man with his daughter Christabel.—In June there was a short trip to Salisbury, Blandford, and Wimborne.—On August 12th he started with his daughter Annot for a holiday in Cumberland, but on the next day he was recalled by a telegram with the intelligence that a change for the worse had come over his wife's health. Lady Airy died on August 13th, 1875. For the last five years of her life she had been very helpless from the effects of a paralytic stroke—a very sad ending to a bright and happy life—and had been continually nursed throughout this time by her two unmarried daughters with the greatest self-denial and devotion. Her husband had been unremitting in his care and attention. Nothing was wanting that the most thoughtful kindness could supply. And in all his trips and excursions his constant and kind letters shewed how anxious he was that she should participate in all his interests and amusements. From the nature of the case it could hardly be said that her death was unexpected, and he received the shock with the manly steadiness which belonged to him. Lady Airy was buried in Playford churchyard.—From Sept. 22nd to Oct. 4 he made a short expedition to Wales (Capel Curig, &c.).—On Dec. 15th he attended the Commemoration at Trinity College, Cambridge.—On Dec. 22nd he went as usual to Playford.
In this year Airy received the high honour of the Freedom of the City of London, in the following communication:
STONE, Mayor.—A Common Council holden in the Chamber of the Guildhall of the City of London, on Thursday the 29th day of April 1875.
Resolved Unanimously
That the Freedom of this City in a Gold Box of the value of One hundred guineas be presented to Sir George Biddell Airy, K.C.B., D.C.L., LL.D. &c., Astronomer Royal, as a recognition of his indefatigable labours in Astronomy, and of his eminent services in the advancement of practical science, whereby he has so materially benefited the cause of Commerce and Civilization.
This Resolution was forwarded with a letter from Benjamin Scott, theChamberlain. Airy's reply was as follows:
ROYAL OBSERVATORY, GREENWICH, S.E.1875, May 1.
I have the honour to acknowledge your letter of April 30, accompanied with Copy of the Resolution of the Common Council of the City of London passed at their Meeting of April 29, under signature of the Town Clerk, That the Freedom of the City of London in a valuable Box be presented to me, in recognition of works stated in the Resolution. And I am requested by you to inform you whether it is my intention to accept the compliment proposed by the Corporation.
In reply, I beg you to convey to the Right Honorable the Lord Mayor and the Corporation that I accept with the greatest pride and pleasure the honour which they propose to offer to me. The Freedom of our Great City, conferred by the spontaneous act of its Municipal Governors, is in my estimation the highest honour which it is possible to receive; and its presentation at this time is peculiarly grateful to me.
I have the honour to be,Sir,Your very obedient servant,G.B. AIRY.
Benjamin Scott, Esq.,&c. &c. &c.Chamberlain of the Corporation of theCity of London.
As it was technically necessary that a Freeman of the City of London should belong to one or other of the City Companies, the Worshipful Company of Spectacle Makers through their clerk (with very great appropriateness) enquired whether it would be agreeable that that Company should have the privilege of conferring their Honorary Freedom on him, and added: "In soliciting your acquiescence to the proposal I am directed to call attention to the fact that this Guild is permitted to claim all manufacturers of Mathematical and Astronomical Instruments within the City of London, which is now pleaded as an apology for the wish that one so distinguished as yourself in the use of such Instruments should be enrolled as a Member of this Craft." In his reply, accepting the Freedom of the Company, Airy wrote thus: "I shall much value the association with a body whose ostensible title bears so close a relation to the official engagements which have long occupied me. I have had extensive experience both in arranging and in using optical and mathematical instruments, and feel that my own pursuits are closely connected with the original employments of the Company." The Freedom of the Company was duly presented, and the occasion was celebrated by a banquet at the Albion Tavern on Tuesday, July 6th.
The Freedom of the City of London was conferred at a Court of Common Council held at the Guildhall on Thursday the 4th of November. In presenting the gold box containing the Freedom, the Chamberlain, in an eloquent speech, first referred to the fact that this was the first occasion on which the Freedom had been conferred on a person whose name was associated with the sciences other than those of war and statecraft. He then referred to the solid character of his work, in that, while others had turned their attention to the more attractive fields of exploration, the discovery of new worlds or of novel celestial phenomena, he had incessantly devoted himself to the less interesting, less obtrusive, but more valuable walks of practical astronomy. And he instanced as the special grounds of the honour conferred, the compilation of nautical tables of extraordinary accuracy, the improvement of chronometers, the correction of the compasses of iron ships, the restoration of the standards of length and weight, and the Transit of Venus Expeditions. In his reply Airy stated that he regarded the honour just conferred upon him as the greatest and proudest ever received by him. He referred to the fact that the same honour had been previously conferred on the valued friend of his youth, Thomas Clarkson, and said that the circumstance of his succeeding such a man was to himself a great honour and pleasure. He alluded to his having received a small exhibition from one of the London Companies, when he was a poor undergraduate at Cambridge, and acknowledged the great assistance that it had been to him. With regard to his occupation, he said that he had followed it in a great measure because of its practical use, and thought it fortunate that from the first he was connected with an institution in which utility was combined with science. The occasion of this presentation was celebrated by a Banquet at the Mansion House on Saturday July 3rd, 1875, to Sir George Airy (Astronomer Royal) and the Representatives of Learned Societies.
There is no doubt that Airy was extremely gratified by the honour that he had received. It was to him the crowning honour of his life, and coming last of all it threw all his other honours into the shade. To his independent and liberal spirit there was something peculiarly touching in the unsolicited approbation and act of so powerful and disinterested a body as the Corporation of the City of London.
AT GREENWICH OBSERVATORY FROM JANUARY 1ST, 1876,TO HIS RESIGNATION OF OFFICE ON AUGUST 15TH,1881.
1876
"At the door from the Front Court to the staircase of the Octagon Room (the original entrance to the Observatory as erected by Sir Christopher Wren), a small porch-shelter has been often desired. I proposed to fix there a fan-roof of quadrantal form, covering the upper flat stone of the external steps.—On a critical examination of the micrometer-screws of the Transit Circle it was found that the corrections, which range from -1°38" to +0°76", indicate considerable wear in the screws; and it was found that as much as one-hundreth part of an inch had been worn away from some of the threads. The old screws were consequently discarded, and new ones were made by Mr Simms.—The adjustment of the Spectroscope has occupied a great deal of attention. There was astigmatism of the prisms; and false light reflected from the base of the prisms, causing loss both of light and of definition. The latter defect was corrected by altering the angles, and then astigmatism was corrected by a cylindrical lens near the slit. The definition in both planes was then found to be perfect.—The number of small planets has now become so great, and the interest of establishing the elements of all their orbits so small,—while at the same time the light of all those lately discovered is very faint, and the difficulty and doubt of observation greatly increased,—that I have begun to think seriously of limiting future observations to a small number of these objects.—All observations with the Spectroscope have been completely reduced; the measures of lines in the spectra of elements being converted into corresponding wave-lengths, and the observations of displacement of lines in the spectra of stars being reduced so as to exhibit the concluded motion in miles per second, after applying a correction for the earth's motion. Sixteen measures of the F line in the spectrum of the Moon as compared with hydrogen give a displacement corresponding to a motion of less than two miles a second, which seems to shew that the method of comparison now adopted is free from systematic error; and this is supported by the manner in which motions of approach and recession are distributed among the stars examined on each night of observation. The results recently obtained appear to be on the whole as consistent as can be expected in such delicate observations, and they support in a remarkable manner the conclusions of Dr Huggins, with regard to the motions of those stars which he examined.—Photographs of the sun have been taken with the photoheliograph on 182 days. On one of the photographs, which was accidentally exposed while the drop slit was being drawn up, there appears to be a faint image of a cloud-like prominence close to the sun's limb, though the exposure probably only amounted to a fraction of a second. A prominence of unusual brilliancy was seen with the Spectroscope about the same time and in the same position with reference to the Sun's limb. All groups of Sun-spots and faculae have been numbered, and the dates of their first and last appearances entered up to the present time. Areas of spots have been measured, and the measures have been reduced to millionths of the Sun's visible hemisphere.—The examination of the readings of the deep-sunk thermometers from 1846 to 1873 has exhibited some laws which had been sufficiently established before this time, and some which were less known. Among the former were the successive retardations of seasons in successive descents, amounting to about four months at the depth of 25 feet; and the successive diminutions of the annual range of temperature. Among the latter is the character of the changes from year to year, which the great length of this series of observations brings well to light. It is found that from year to year the mean temperature of the surface for the year, varying by three or four degrees of Fahrenheit, follows in its changes the mean temperature of the atmosphere for the year, and that the changes of annual temperature are propagated downwards, retarded in phase and diminishing in amount of change, in the same manner (though probably not following the same law) as the season changes. The inference from this is, that changes of temperature come entirely from the exterior and in no discoverable degree from the interior; an inference which may be important in regard both to solar action and to geology. —Referring to the Transit of Venus observations: In the astronomical part of the reductions, there has been great labour and difficulty in the determination of local sidereal times; some books of observations required extensive transcription; some instrumental errors are still uncertain; the latter determinations have perplexed us so much that we are inclined to believe that, in spite of the great facilities of reduction given by the transit instrument, it would be better to rely on the altazimuth for time-determinations…. In the photographic part, I have confined my attention entirely to measures of the distance between the centres of the Sun and Planet, a troublesome and complex operation.—Referring to the progress of the Numerical Lunar Theory: With a repetition of grant from the Treasury, I have usually maintained four junior computers on this work. The progress, though considerable, has not been so great as I had hoped, by reason of the excessive personal pressure upon me during the whole year.—I wrote a letter of congratulation to Le Verrier on the completion of his great work of Planetary Tables.—On May 13th the Queen was at South Kensington, and I attended to explain the astronomical instruments, and shewed Her Majesty one of the Transit of Venus photographs."
Of private history: He returned from his Playford visit on the 18th of January.—In April there was a two-day trip to Colchester.—From June 13th to July 12th he was travelling in the North of Scotland and the Orkneys with his daughters, staying for a short time with Mr Webster, M.P., at Aberdeen, and with Mr Newall at Newcastle.—In September there was a week's run to Birkenhead and Keswick.—In November a week's run to Playford.—From the 13th to 15th of December he was at Cambridge, and on the 28th he went to Playford for the usual winter stay there.
1877
"In April of this year I was much engaged on the subject of Mr Gill's expedition to Ascension to observe for the determination of the parallax of Mars at the approaching opposition of that planet.—A large Direct-vision Spectroscope has been quite recently made by Mr Hilger under Mr Christie's direction on a new plan, in which either great dispersion or great purity of spectrum is obtained by the use of 'Half-prisms,' according as the incident pencil falls first on the perpendicular or on the oblique face. In this Spectroscope either one or two half prisms can be used at pleasure, according to the dispersion required, and there is facility for increasing the train to three or four half-prisms, though the dispersion with two only is nearly double of that given by the large ten-prism Spectroscope. The definition in this form of Spectroscope appears to be very fine.—At the end of May 1876, spectroscopic determinations of the Sun's rotation were made by observations of the relative displacement of the Fraunhofer lines at the east and west limbs respectively. The results are in close agreement with the value of the rotation found from observations of Sun-spots. A similar determination has also been made in the case of Jupiter, with equally satisfactory results.—An Electrometer on Sir William Thomson's plan, for continuous photographic registration of atmospheric electricity has been received from Mr White of Glasgow. It was mounted in December.—The computation of the photographic records of the barometer from 1854 to 1873 has so far advanced that we can assert positively that there is no trace of lunar tide in the atmosphere; but that there is a strongly marked semi-diurnal solar tide, accompanied with a smaller diurnal tide. We are at present engaged in comparing the barometric measures with the directions of the wind.—Regarding the distribution of the printed observations: There is no extensive wish for separate magnetic observations, but general magnetic results are in great demand, especially for mining operations, and to meet this a map of magnetic declination is furnished in the newspaper called the 'Colliery Guardian.'—As regards the operations for the Transit of Venus: The computing staff has by degrees been reduced to two junior computers within the Observatory; and one or two computers external to the Observatory, who are employed on large groups of systematic calculations. The principal part of the calculations remaining at the date of the last Report was that applying to the determination of the geographical longitudes of fundamental stations. At the moment of my writing, the last of these (the longitude of Observatory Bay, Kerguelen) is not absolutely finished:… The method of determining the geographical longitude of the principal station in each group by vertical transits of the Moon has been found very successful at Honolulu and Rodriguez. For stations in high south latitude, horizontal transits are preferable.—As regards the Numerical Lunar Theory: With the view of preserving, against the ordinary chances of destruction or abandonment, a work which is already one of considerable magnitude, I have prepared and have printed as Appendix to the Greenwich Observations (with additional copies as for a separate work) the ordinary Equations of Lunar Disturbance, the novel theory of Symbolical Variations, and the Numerical Developments of the quantities on the first side of the Equations.—At various times from February to May I was engaged on the reduction of Malta Tides, and on a Paper concerning the same.—In July I was awarded the Albert Medal for my Compass corrections, and received the same from the Prince of Wales.—In February, Campbell's instrument for the registration of sunshine was introduced: it was mounted in July."
Of private history: "I was at Playford until Jan. 19th, in close correspondence as usual with Mr Christie at the Observatory, and attending to my Numerical Lunar Theory.—From Mar. 29th to Apr. 2nd I went on a short trip to Hereford, Worcester, &c.—From June 8th to 20th I was at Playford.—From Aug. 13th to Sept. 8th Airy was on an expedition in Ireland, chiefly in the North and West, with his daughters. When at Dublin he visited Grubb's instrument factory. On the return journey he stayed for some time in the Lake District of Cumberland, and took soundings in the neighbourhood of the place of the 'floating island' in Derwentwater."
Airy took the greatest interest in antiquarian matters, whether military or ecclesiastical, and his feelings on such matters is well illustrated by the following letter:
ROYAL OBSERVATORY, GREENWICH, S.E.1877, February 27.
I venture to ask if you can assist me in the following matter.
In the Parish Church of Playford, near Ipswich, Suffolk, was a splendid brass tombstone to Sir Thomas Felbrigg. By an act of folly and barbarism, almost unequalled in the history of the world, the Incumbent and Curate nearly destroyed the brass inscription surrounding the image of the Knight.
This tombstone is figured in Gough's Sepulchral Antiquities, which, I presume, is to be found in the British Museum.
And I take the liberty to ask if you would kindly look at the engraving, and give me any suggestion as to the way in which some copies of it could be made, in a fairly durable form. I am connected with the parish of Playford, and am anxious to preserve for it this memorial of a family of high rank formerly resident there.
I am, dear Sir,Very faithfully yours,G.B. AIRY.
T. Winter Jones, Esq.
To this request Mr Winter Jones immediately acceded, and the engraving was duly photographed, and copies were circulated with a historical notice of Sir George (not Sir Thomas) Felbrigg and a history of the Monument. Sir George Felbrigg was Esquire-at-Arms to Edward III., and Lord of the Manor of Playford: he died in 1400, and was buried in the North wall of Playford Church.
1878
The Report to the Board of Visitors has this paragraph: "I continue to remark the approaching necessity for Library extension. Without having absolutely decided on a site, I may suggest that I should wish to erect a brick building, about 50 feet by 20, consisting of two very low stories (or rather of one story with a gallery running round its walls), so low that books can be moved by hand without necessity for a ladder.—In the month of December, 1877, the azimuthal error of the Transit Circle had increased to 10". A skilful workman, instructed by Mr Simms, easily reduced the error to about 2".5 (which would leave its mean error nearly 0), the western Y being moved to the north so far as to reduce the reading of the transit micrometer, when pointed to the south, from 35r.500 to 35r.000. The level error was not sensibly affected.—The Sidereal Standard Clock preserves a rate approaching to perfection, so long as it is left without disturbance of the galvanic-contact springs (touched by its pendulum), which transmit signals at every second of time to sympathetic clocks and the chronograph. A readjustment of these springs usually disturbs the rate.—To facilitate the observations of stars, a new working catalogue has been prepared, in which are included all stars down to the third magnitude, stars down to the fifth magnitude which have not been observed in the last two catalogues, and a list of 258 stars of about the sixth magnitude of which the places are required for the United States Coast Survey. The whole number of stars in our new working list is about 2500. It may be here mentioned that an extensive series of observations was made, during the autumn, of about 70 stars, at the request of Mr Gill, for comparison with Mars, Ariadne, and Melpomene.—On Apr. 10th last, a very heavy fall of rain took place. Between Apr. 10d. 5h. and Apr. 11d. 2h., 2.824 inch. was recorded, and 75 per cent. of this, or 2.12 inch., fell in the eight hours between 13-1/2h. and 21-1/2h.; and on May 7, 1 inch of rain fell in 50 minutes, of which 1/2 inch fell in 15 minutes.—The supplementary compensation continues to be applied with success to Government chronometers which offer facilities for its introduction, and a marked improvement in the performance of chronometers returned after repair by the makers appears to have resulted from the increased attention now given to the compensation. Of the 29 competitive chronometers, 25 have the supplementary compensation."—With regard to the reduction of the observations of the Transit of Venus: After reference to the difficulties arising from the errors and the interpretation of the language used by some of the observers, the Report continues thus: "Finally a Report was made to the Government on July 5th, giving as the mean result for Mean Solar Parallax 8".76; the results from ingress and from egress, however, differing to the extent of 0".11…. After further examination and consideration, the result for parallax has been increased to 8".82 or 8".83. The results from photography have disappointed me much. The failure has arisen, perhaps sometimes from irregularity of limb, or from atmospheric distortion, but more frequently from faintness and from want of clear definition. Many photographs, which to the eye appeared good, lost all strength and sharpness when placed under the measuring microscope. A final result 8".17 was obtained from Mr Burton's measures, and 8".08 from Capt. Tupman's.—With regard to the Numerical Lunar Theory: A cursory collection of the terms relating to the Areas (in the Ecliptic) led me to suppose that there might be some error in the computations of the Annual Equation and related terms. A most jealous re-examination has however detected nothing, and has confirmed my belief in the general accuracy of the numerical computations. I dare not yet venture to assume an error in Delaunay's theory; but I remember that the Annual Equation gave great trouble to the late Sir John Lubbock, and that he more than once changed his conclusions as to its true value.—In February I was engaged on the drawings and preparations for my intended Lecture at Cockermouth on the probable condition of the interior of the Earth. The Lecture was delivered in April.—At different times in the autumn I was engaged on diagrams to illustrate the passage of rays through eye-pieces and double-image micrometers.—The miscellaneous scientific correspondence, which was always going on, was in this year unusually varied and heavy."
Of private history: He was at Playford till Jan. 26th.—In April he went to Cockermouth to deliver his Lecture above-mentioned: the journey was by Birmingham, where he stayed for two days (probably with his son Osmund, who resided there), to Tarn Bank (the residence of Isaac Fletcher, M.P.): the lecture was delivered on the 22nd: he made excursions to Thirlmere and Barrow, and to Edward I.'s Monument, and returned to Greenwich on the 27th.—From June 17th to 28th he was at Playford.—From Aug. 19th to Sept. 17th he was travelling in Scotland, visiting the Tay Bridge, the Loch Katrine Waterworks, &c., and spent the last fortnight of his trip at Portinscale, near Keswick. On Dec. 23rd he went to Playford.
1879
"The manuscripts of every kind, which are accumulated in the ordinary transactions of the Observatory, are preserved with the same care and arranged on the same system as heretofore. The total number of bound volumes exceeds 4000. Besides these there is the great mass of Transit of Venus reductions and manuscripts, which when bound may be expected to form about 200 volumes.—With regard to the numerous group of Minor Planets, the Berlin authorities have most kindly given attention to my representation, and we have now a most admirable and comprehensive Ephemeris. But the extreme faintness of the majority of these bodies places them practically beyond the reach of our meridian instrument, and the difficulty of observation is in many cases further increased by the large errors of the predicted places.—After a fine autumn, the weather in the past winter and spring has been remarkably bad. More than an entire lunation was lost with the Transit Circle, no observation of the Moon on the meridian having been possible between January 8 and March 1, a period of more than seven weeks. Neither Sun nor stars were visible for eleven days, during which period the clock-times were carried on entirely by the preceding rate of the clock. The accumulated error at the end of this time did not exceed 0s'3.—Some difficulty was at first experienced with the Thomson Electrometer, which was traced to want of insulation. This has been mastered by the use of glass supporters, which carry some sulphuric acid. The instrument is now in excellent order, and the photographic registers have been perfectly satisfactory since 1879, February, when the new insulators were applied.—From the annual curves of diurnal inequality, deduced from the Magnetic Reductions, most important inferences may be drawn, as to the connection between magnetic phenomena and sun-spots. These annual curves shew a well-marked change in close correspondence with the number of sun-spots. About the epoch of maximum of sun-spots they are large and nearly circular, having the same character as the curves for the summer months; whilst about the time of sun-spot minimum they are small and lemniscate-shaped, with a striking resemblance to the curves for the winter months. The connection between changes of terrestrial magnetism and sun-spots is shewn in a still more striking manner by a comparison which Mr Ellis has made between the monthly means of the diurnal range of declination and horizontal force, and Dr R. Wolf's 'relative numbers' for frequency of sun-spots.—The records of sunshine with Campbell's Registering Sun-dial are preserved in a form easily accessible for reference, and the results are communicated weekly to the Agricultural Gazette.—Prof. Oppolzer's results for the determination of the longitudes of Vienna and Berlin, made in 1877, have now been made public. They shew a remarkable agreement of the Chronometric determination formerly made with the Telegraphic. It may be of interest to recall the fact that a similar agreement was found between the Chronometric and Telegraphic determinations of the longitude of Valentia.—For observing the Transit of Venus of 1882, the general impression appears to be that it will be best to confine our observations to simple telescopic observations or micrometer observations at Ingress and Egress, if possible at places whose longitudes are known. For the first phenomenon (accelerated ingress) the choice of stations is not good; but for the other phenomena (retarded ingress, accelerated egress, retarded egress) there appears to be no difficulty.—With regard to the Numerical Lunar Theory: Respecting the discordance of Annual Equation, I suspend my judgment. I have now discussed the theory completely; and in going into details of secular changes, I am at this time engaged on that which is the foundation of all, namely, the change of excentricity of the Solar Orbit, and its result in producing Lunar Acceleration. An important error in the theoretical formulae for Variations of Radius Vector, Longitude, and Latitude, was discovered; some calculations depending on them are cancelled."—Referring to the magnitude of the printed volume of "Greenwich Observations," and the practicability of reducing the extent of it, the Report states thus: "The tendency of external scientific movement is to give great attention to the phenomena of the Solar disc (in which this Observatory ought undoubtedly to bear its part). And I personally am most unwilling to recede from the existing course of magnetical and meteorological observations….The general tendency of these considerations is to increase the annual expenses of the Observatory. And so it has been, almost continuously, for the last 42 years. The annual ordinary expenses are now between 2-1/2 and 3 times as great as in my first years at the Royal Observatory.—Mr Gill was appointed to the Cape Observatory, and I wrote out instructions for him in March: there was subsequently much correspondence respecting the equipment and repairs of the Cape Observatory."—In the Monthly Notices of the Royal Astronomical Society for January an article had appeared headed "Notes on the late Admiral Smyth's Cycle of Celestial Objects, Vol. II." by Mr Herbert Sadler. In this article Mr Sadler had criticized the work of Admiral Smyth in a manner which Airy regarded as imputing bad faith to Admiral Smyth. He at once took up the defence of his old friend very warmly, and proposed certain Drafts of Resolutions to the Council of the Society. These Resolutions were moved, but were amended or negatived, and Airy immediately resigned his office of Vice-President. There was considerable negociation on the subject, and discussion with Lord Lindsay, and on May 9th Airy's Resolutions were accepted by the Council.—In October Airy inspected the "Faraday" telegraph ship, then lying in the river near Messrs Siemens' works, and broke his finger by a fall on board the vessel.—In this year Airy wrote and circulated a letter to the Members of the Senate of the University of Cambridge, on the subject of the Papers set in the Smith's Prizes Examination. In this letter, as on former occasions, he objected much to the large number of questions in "purely idle algebra, arbitrary combinations of symbols, applicable to no further purpose." And in particular he singled out for comment the following question, which was one of those set, "Using the term circle as extending to the case where the radius is a pure imaginary, it is required to construct the common chord of two given circles." This drew forth as usual a rejoinder from Prof. Cayley, who wrote enclosing a solution of his problem, but not at all to Airy's satisfaction, who replied as follows: "I am not so deeply plunged in the mists of impossibles as to appreciate fully your explanation in this instance, or to think that it is a good criterion for University candidates."
Of private history: On Jan. 21st he returned from Playford.—On March 22nd he attended the funeral of his sister at Little Welnetham near Bury St Edmunds: Miss Elizabeth Airy had lived with him at the Observatory from shortly after his appointment.—For about a week at the end of April he was visiting Matlock, Edensor, and Buxton.—From June 14th to July 18th he was staying at Portinscale near Keswick.—He was at Playford for two or three days in October, and went there again on Dec. 23rd for his usual winter holiday.
The following letter, relating to the life of Thomas Clarkson, waswritten to Dr Merivale, Dean of Ely, after reading the account in the"Times" of October 10th of the unveiling of a statue of Clarkson nearWare:
ROYAL OBSERVATORY, GREENWICH,LONDON, S.E.1879, October 11.
Pardon my intrusion on you, in reference to a transaction which has greatly interested me—the honour paid by you to the memory of Thomas Clarkson. With very great pleasure I have heard of this step: and I have also been much satisfied with the remarks on it in the "Times." I well remember, in Clarkson's "History of the Abolition," which I read some 60 years ago, the account of the circumstance, now commemorated by you, which determined the action of his whole subsequent life.
It is not improbable that, among those who still remember Clarkson, my acquaintance with him began at the earliest time of all. I knew him, intimately, from the beginning of 1815 to his death. The family which he represented must have occupied a very good position in society. I have heard that he sold two good estates to defray the expenses which he incurred in his personal labours for Abolition: and his brother was Governor of Sierra Leone (I know not at what time appointed). Thomas Clarkson was at St John's College; and, as I gather from circumstances which I have heard him mention, must have been a rather gay man. He kept a horse, and at one time kept two. He took Orders in the Church; and on one occasion, in the course of his Abolition struggle, he preached in a church. But he afterwards resolutely laid aside all pretensions to the title of Minister of the Church, and never would accept any title except as layman. He was, however, a very earnest reader of theology during my acquaintance with him, and appeared to be well acquainted with the Early Fathers.
The precise words in which was announced the subject for Prize Essay in the University were "Anne liceat invitos in servitutem trahere."
After the first great victory on the slave trade question, he established himself in a house on the bank of Ullswater. I have not identified the place: from a view which he once shewed me I supposed it to be near the bottom of the lake: but from an account of the storm of wind which he encountered when walking with a lady over a pass, it seemed to be in or near Patterdale. When the remains of a mountaineer, who perished in Helvellyn (as described in Scott's well-known poem), were discovered by a shepherd, it was to Mr Clarkson that the intelligence was first brought.