Autobiography of Sir George Biddell Airy

by George Biddell Airy

CHAPTER X.

AT THE WHITE HOUSE, GREENWICH. FROM HIS RESIGNATION OF OFFICE ON AUGUST 15TH, 1881, TO HIS DEATH ON JANUARY 2ND, 1892.

HISTORY OF HIS LIFE AFTER HIS RESIGNATION OF OFFICE.

On the 16th of August 1881 Airy left the Observatory which had been his residence for nearly 46 years, and removed to the White House. Whatever his feelings may have been at the severing of his old associations he carefully kept them to himself, and entered upon his new life with the cheerful composure and steadiness of temper which he possessed in a remarkable degree. He was now more than 80 years old, and the cares of office had begun to weigh heavily upon him: the long-continued drag of the Transit of Venus work had wearied him, and he was anxious to carry on and if possible complete his Numerical Lunar Theory, the great work which for some years had occupied much of his time and attention. His mental powers were still vigorous, and his energy but little impaired: his strong constitution, his regular habits of life, the systematic relief which he obtained by short holiday expeditions whenever he found himself worn with work, and his keen interest in history, poetry, classics, antiquities, engineering, and other subjects not immediately connected with his profession, had combined to produce this result. And in leaving office, he had no idea of leaving off work; his resignation of office merely meant for him a change of work. It is needless to say that his interest in the welfare and progress of the Observatory was as keen as ever; his advice was always at the service of his successor, and his appointment as Visitor a year or two after his resignation gave him an official position with regard to the Observatory which he much valued. The White House, which was to be his home for the rest of his life, is just outside one of the upper gates of the Park, and about a quarter of a mile from the Observatory. Here he resided with his two unmarried daughters. The house suited him well and he was very comfortable there: he preferred to live in the neighbourhood with which he was so familiar and in which he was so well known, rather than to remove to a distance. His daily habits of life were but little altered: he worked steadily as formerly, took his daily walk on Blackheath, made frequent visits to Playford, and occasional expeditions to the Cumberland Lakes and elsewhere.

The work to which he chiefly devoted himself in his retirement was the completion of his Numerical Lunar Theory. This was a vast work, involving the subtlest considerations of principle, very long and elaborate mathematical investigations of a high order, and an enormous amount of arithmetical computation. The issue of it was unfortunate: he concluded that there was an error in some of the early work, which vitiated the results obtained: and although the whole process was published, and was left in such a state that it would be a comparatively simple task for a future astronomer to correct and complete it, yet it was not permitted to the original author of it to do this. To avoid the necessity of frequent reference to this work in the history of Airy's remaining years, it will be convenient to summarize it here. It was commenced in 1872: "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." From this time forward till his power to continue it absolutely failed, he pursued the subject with his usual tenacity of purpose. During his tenure of office every available opportunity was seized for making progress with his Lunar Theory, and in every Report to the Visitors a careful statement was inserted of the state in which it then stood. And, after his resignation of office, it formed the bulk of his occupation. In 1873 the Theory was formed, and by 1874 it was so far advanced that he published in the Monthly Notices of the Royal Astronomical Society a statement of the fundamental points of the Theory. In 1875, the Theory having advanced to a stage where extensive arithmetical computation was required, he obtained a small grant from the Government in aid of the expense of the work, and other grants were made in subsequent years. By 1878 the calculations were so far advanced that an opinion could be formed as to the probable accuracy of the Theory, and the following remark is made: "A cursory collation 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;" but no error could be discovered and the work proceeded. The complex character of the Theory, and the extreme care required in the mathematical processes, are well illustrated by the following statement, which occurs in the Report of 1879, "An important error in the theoretical formulae for Variations of Radius Vector, Longitude, and Latitude, was discovered; some calculations depending on them are cancelled." In 1880 and 1881 the work was continued, but was "sadly interrupted by the pressure of the Transit of Venus work and other business." After his resignation of the Office of Astronomer Royal he had no further public assistance, and did much of the computations himself, but a sum of £100 was contributed by Mr De La Rue in furtherance of the work, and this sum was spent on computers. In his retirement the work made good progress, and on Dec. 31st, 1882, he made the following note: "I finished and put in general order the final tables of Equations of Variations. This is a definite point in the Lunar Theory…. I hope shortly to take up severely the numerical operations of the Lunar Theory from the very beginning." The work was continued steadily through 1883, and on Mar. 24th, 1884, he made application through the Board of Visitors to the Admiralty to print the work: after the usual enquiries as to the expense this was acceded to, and copy was sent to the printers as soon as it was ready. The first printed proofs were received on Feb. 5th, 1885, and the whole book was printed by the end of 1886. From the frequent references in his journal to errors discovered and corrected during the progress of these calculations, it would seem likely that his powers were not what they had been, and that there was a probability that some important errors might escape correction. He was far too honest to blind himself to this possibility, and in the Preface to his Numerical Lunar Theory he says thus: "I have explained above that the principle of operations was, to arrange the fundamental mechanical equations in a form suited for the investigations of Lunar Theory; to substitute in the terms of these equations the numerical values furnished by Delaunay's great work; and to examine whether the equations are thereby satisfied. With painful alarm, I find that they are not satisfied; and that the discordance, or failure of satisfying the equations, is large. The critical trial depends on the great mass of computations in Section II. These have been made in duplicate, with all the care for accuracy that anxiety could supply. Still I cannot but fear that the error which is the source of discordance must be on my part. I cannot conjecture whether I may be able to examine sufficiently into this matter." He resolutely took in hand the revision of his work, and continued it till October 1888. But it is clear from the entries in his journal that his powers were now unequal to the task, and although from time to time he suspected that he had discovered errors, yet it does not appear that he determined anything with certainty. He never doubted that there were important errors in the work, and later on he left the following private note on the subject:

NUMERICAL LUNAR THEORY.

1890, Sept. 29.

I had made considerable advance (under official difficulties) in calculations on my favourite Numerical Lunar Theory, when I discovered that, under the heavy pressure of unusual matters (two Transits of Venus and some eclipses) I had committed a grievous error in the first stage of giving numerical value to my Theory.

My spirit in the work was broken, and I have never heartily proceeded with it since.

G.B. AIRY.

Probably the error referred to here is the suspected error mentioned above in his Report of 1878, as to which he subsequently became more certain.

Whatever may be the imperfections of the Numerical Lunar Theory, it is a wonderful work to have been turned out by a man 85 years old. In its idea and inception it embodies the experience of a long life actively spent in practical science. And it may be that it will yet fulfil the objects of its author, and that some younger astronomer may take it up, correct its errors (wherever they may be), and fit it for practical use. And then the labour bestowed upon it will not have been in vain.

Subject always to the absorbing occupations of the Lunar Theory he amused himself with reading his favourite subjects of History and Antiquities. His movements during the remainder of the year 1881 were as follows: In September he paid a two days' visit to Lady Herschel at Hawkhurst. From Oct. 4th to 17th he was at the Cumberland Lakes and engaged in expeditions in the neighbourhood. From Nov. 5th to 8th he was at Cambridge, inspecting Prof. Stuart's workshops, and other scientific institutions. On Dec. 13th he went to Playford.—Amongst miscellaneous matters: in November he wrote to Mr Rothery on the loss of the 'Teuton' at some length, with suggestions for the safer construction of such vessels.—In October he was asked for suggestions regarding the establishment of a "Standard Time" applicable to the railway traffic in the United States: he replied as follows:

1881, Oct. 31.

SIR,

I have to acknowledge your letter of October 17, introducing to my notice the difficulty which appears to be arising in America regarding a "Standard Time," for extensive use throughout N. America "applicable to railway traffic only." The subject, as including considerations of convenience in all the matters to which it applies, is one of difficulties probably insuperable. The certainty, however, that objections may be raised to every scheme, renders me less timid in offering my own remarks; which are much at your service.

I first comment upon your expression of "Standard Time… applicable to railway traffic only." But do you mean this as affecting the transactions between one railway and another railway, or as affecting each railway and the local interests (temporal and others) of the towns which it touches? The difference is so great that I should be disposed to adopt it as marking very strongly the difference to be made between the practices of railways among themselves and the practices of railways towards the public; and will base a system on that difference.

As regards the practices of railways among themselves: if the various railways of America are joined and inosculated as they are in England, it appears to me indispensable that they have one common standard among themselves: say Washington Observatory time. But this is only needed for the office-transactions between the railways; it may be kept perfectly private; never communicated to the public at all. And I should recommend this as the first step.

There will then be no difficulty in deducing, from these private Washington times, the accurate local times at those stations (whose longitude is supposed to be fairly well known, as a sailor with a sextant can determine one in a few hours) which the railway authorities may deem worthy of that honour; generally the termini of railways. Thus we shall have a series of bases of local time, of authoritative character, through the country.

Of such bases we have two, Greenwich and Dublin: and they are separated by a sea-voyage. In the U.S. of America there must be a greater number, and probably not so well separated. Still it is indispensable to adopt such a system of local centers.

No people in this world can be induced to use a reckoning which does not depend clearly upon the sun. In all civilized countries it depends (approximately) on the sun's meridian passage. Even the sailor on mid-ocean refers to that phenomenon. And the solar passage, with reasonable allowance, 20m. or 30m. one way or another, must be recognized in all time-arrangements as giving the fundamental time. The only practical way of doing this is, to adopt for a whole region the fundamental time of a center of that region.

And to this fundamental time, the local time of the railway, as now entering into all the concerns of life, must be adapted. A solicitor has an appointment to meet a client by railway; a physician to a consultation. How is this to be kept if the railway uses one time and every other act of life another?

There is one chain of circumstances which is almost peculiar—that of the line from New York to San Francisco. Here I would have two clocks at every station: those on the north side all shewing San Francisco time, and those on the south all shewing New York time. Every traveller's watch would then be available to the end of his journey.

A system, fundamentally such as I have sketched, would give little trouble, and may I think be adopted with advantage.

I am, Sir,
Your faithful servant,
G.B. AIRY.

Mr Edward Barrington.

1882

He returned from Playford on Jan. 17: his other movements during the year were as follows: from Apr. 27th to May 11th he was at Playford; and again from August 1st to 24th. From Oct. 9th to Nov. 1st he was travelling with his two unmarried daughters in the Lake District of Cumberland: the journey was by Furness and Coniston to Portinscale near Keswick; on Oct. 13th he fell and sprained his ankle, and his excursions for the rest of the time were mainly conducted by driving. Shortly after his return, on Nov. 11th, while walking alone on Blackheath, he was seized with a violent attack of illness, and lay helpless for some time before he was found and brought home: he seems however to have recovered to a great extent in the course of a day or two, and continued his Lunar Theory and other work as before. On June 22nd he made the following sad note, "This morning, died after a most painful illness my much-loved daughter-in-law, Anna Airy, daughter of Professor Listing of Göttingen, wife of my eldest son Wilfrid." In February he wrote out his reminiscences of the village of Playford during his boyhood.

In June he was much disturbed in mind on hearing of some important alterations made by the Astronomer Royal in the Collimators of the Transit Circle, and some correspondence ensued on the subject.—During the year he had much correspondence on the subject of the subsidences on Blackheath.

The following letter was written in reply to a gentleman who had asked whether it could be ascertained by calculation how long it is since the Glacial Period existed:

1882, July 4.

SIR,

I should have much pleasure in fully answering your questions of July 3 if I were able to do so: but the subject really is very obscure.

(1) Though it is recognized that the glacial period (or periods) is late, I do not think that any one has ventured to fix upon a rude number of years since elapsed.

(2) We have no reason to think that the mean distance of the earth from the sun has sensibly altered. There have been changes in the eccentricity of the orbit (making the earth's distance from the sun less in one month and greater in the opposite month), but I do not perceive that this would explain glaciers.

(3) I consider it to be certain that the whole surface of the earth, at a very distant period, was very hot, that it has cooled gradually, and (theoretically and imperceptibly) is cooling still. The glaciers must be later than these hot times, and later than our last consolidated strata: but this is nearly all that I can say.

I am, Sir, Your obedient Servant,
G.B. AIRY.

James Alston, Esq.

1883

From May 2nd to 29th he was at Playford. From July 10th to 20th he was travelling in South Wales with his daughters.—From Oct. 10th to Nov. 10th he was at Playford.—Between Nov. 20th of this year and Jan. 4th of the year 1884, he sat several times to Mr John Collier for his portrait: the picture was exhibited in the Academy of 1884; it is a most successful and excellent likeness.

Throughout the year he was very busy with the Numerical Lunar Theory.—In March he was officially asked to accept the office of Visitor of the Royal Observatory, which he accepted, and in this capacity attended at the Annual Visitation on June 2nd, and addressed a Memorandum to the Visitors on the progress of his Lunar Theory.—On March 12th he published in several newspapers a statement in opposition to the proposed Braithwaite and Buttermere Railway, which he considered would be injurious to the Lake District, in which he took so deep an interest.—In May he communicated to "The Observatory" a statement of his objections to a Theory advanced by Mr Stone (then President of the Royal Astronomical Society) to account for the recognized inequality in the Mean Motion of the Moon. This Theory, on a subject to which Airy had given his incessant attention for so many years, would naturally receive his careful attention and criticism, and it attracted much general notice at the time.—In December he wrote to the Secretary of the Royal Astronomical Society his opinion as to the award of the Medal of the Society. In this letter he stated the principles which guided him as follows: "I have always maintained that the award of the Medal ought to be guided mainly by the originality of communications: that one advance in a new direction ought in our decision to outweigh any mass of work in a routine already established: and that, in any case, scientific utility as distinguished from mere elegance is indispensable."—In July Lieut. Pinheiro of the Brazilian Navy called with an autograph letter of introduction from the Emperor of Brazil. The Lieutenant desired to make himself acquainted with the English system of Lighthouses and Meteorology, and Airy took much trouble in providing him with introductions through which he received every facility for the thorough accomplishment of his object.—On Oct. 8th he forwarded to Prof. Cayley proofs of Euclid's Propositions I. 47 and III. 35 with the following remarks: "I place on the other side the propositions which may be substituted (with knowledge of Euclid's VI. book) for the two celebrated propositions of the geometrical books. They leave on my mind no doubt whatever that they were invented as proofs by ratios, and that they were then violently expanded into cumbrous geometrical proofs."—On June 28th he declined to sign a memorial asking for the interment of Mr Spottiswoode in Westminster Abbey, stating as his reason, "I take it, that interment possessing such a public character is a public recognition of benefits, political, literary, or philosophical, whose effects will be great and durable. Now I doubt whether it can be stated that Mr Spottiswoode had conferred such benefits on Society. "But he adds at length his cordial recognition of Mr Spottiswoode's scientific services.—Throughout his life Airy was a regular attendant at church, and took much interest in the conduct of the Church services. In October of this year he wrote a long letter to the Vicar of Greenwich on various points, in which occurs the following paragraph: "But there is one matter in the present form of the Church Service, on which my feeling is very strong, namely the (so-called, I believe) Choral Service, in the Confession, the Prayer, and the Creed. I have long listened with veneration to our noble Liturgy, and I have always been struck with the deep personally religious feeling which pervades it, especially those parts of it which are for 'The People.' And an earnest Priest, earnestly pressing these parts by his vocal example on the notice of the People, can scarcely fail to excite a corresponding earnestness in them. All this is totally lost in the choral system. For a venerable persuasion there is substituted a rude irreverential confusion of voices; for an earnest acceptance of the form offered by the Priest there is substituted—in my feeling at least—a weary waiting for the end of an unmeaning form." He also objected much to singing the responses to the Commandments.

1884

From Apr. 29th to May 30th he was at Playford, concluding his Journal there with the note "So ends a pleasant Vacation."—On June 11th he went to Cambridge and attended the Trinity College Commemoration Service, and dined in Hall.—From Aug. 14th to Sept. 11th he was at Playford.—On Sept. 26th he made an expedition to Guildford and Farnham.—During this year he was closely engaged on the Numerical Lunar Theory, and for relaxation was reading theology and sundry books of the Old Testament.

On June 7th he attended at the Visitation of the Royal Observatory.—In a letter written in April to Lt.-Col. Marindin, R.A., on the subject of wind pressure there occurs the following remark: "When the heavy gusts come on, the wind is blowing in directions changing rapidly, but limited in extent. My conclusion is that in arches of small extent (as in the Tay Bridge) every thing must be calculated for full pressure; but in arches of large extent (as in the Forth Bridge) every thing may be calculated for small pressure. And for a suspension bridge the pressure is far less dangerous than for a stiff arch."—In January he had some correspondence with Professor Tyndall on the Theory of the "White Rainbow," and stated that he thoroughly agreed with Dr Young's explanation of this phaenomenon. —The following is extracted from a letter on May 1st to his old friend Otto Struve: "I received from you about 3 or 4 weeks past a sign of your friendly remembrance, a copy of your paper on the Annual Parallax of Aldebaran. It pleased me much. Especially I was delighted with your noble retention of the one equation whose result differed so sensibly from that of the other equations. It is quite possible, even probable, that the mean result is improved by it. I have known such instances. The first, which attracted much attention, was Capt. Kater's attempt to establish a scale of longitude in England by reciprocal observations of azimuth between Beachy Head and Dunnose. The result was evidently erroneous. But Colonel Colby, on examination of the original papers, found that some observations had been omitted, as suspicious; and that when these were included the mean agreed well with the scale of observation inferred from other methods."—In a letter to the Rev. R.C.M. Rouse, acknowledging the receipt of a geometrical book, there occurs the following paragraph: "I do not value Euclid's Elements as a super-excellent book of instruction—though some important points are better presented in it than in any other book of geometrical instruction that I have seen. But I value it as a book of strong and distinct reasoning, and of orderly succession of reasonings. I do not think that there is any book in the world which presents so distinctly the 'because…… therefore…….' And this is invaluable for the mental education of youth."—In May he was in correspondence with Professor Balfour Stewart regarding a projected movement in Terrestrial Magnetism to be submitted to the British Association. Airy cordially approved of this movement, and supported it to the best of his ability, stating that in his opinion what was mainly wanted was the collation of existing records.—In January and February he was much pressed by Prof. Pritchard of Oxford to give his opinion as to the incorrectness of statements made by Dr Kinns in his Lectures on the Scientific Accuracy of the Bible. Airy refused absolutely to take part in the controversy, but he could not escape from the correspondence which the matter involved: and this led up to other points connected with the early history of the Israelites, a subject in which he took much interest.

1885

From May 4th to June 3rd he was at Playford.—From July 2nd to 22nd he was in the Lake District. The journey was by Windermere to Kentmere, where he made enquiries concerning the Airy family, as it had been concluded with much probability from investigations made by his nephew, the Rev. Basil R. Airy, that the family was settled there at a very early date. Some persons of the name of Airy were still living there. He then went on by Coniston and Grasmere to Portinscale, and spent the rest of his time in expeditions amongst the hills and visits to friends.—On July 28th he went to Woodbridge in Suffolk and distributed the prizes to the boys of the Grammar School there.—From Oct. 9th to Nov. 12th he was again at Playford.—Throughout the year he was busily engaged on the Numerical Lunar Theory, and found but little time for miscellaneous reading.

Of printed papers by Airy in this year the most important was one on the "Results deduced from the Measures of Terrestrial Magnetic Force in the Horizontal Plane," &c. This was a long Paper, communicated to the Royal Society, and published in the Phil. Trans., and was the last Scientific Paper of any importance (except the Volume of the Numerical Lunar Theory) in the long list of "Papers by G.B. Airy." The preparation of this Paper took much time.—Of miscellaneous matters: In May a Committee of the Royal Society had been appointed to advise the India Office as to the publication of Col. J. Herschel's pendulum observations in India; and Airy was asked to assist the Committee with his advice. He gave very careful and anxious consideration to the subject, and it occupied much time.—In the early part of the year he was asked by Sir William Thomson to assist him with an affidavit in a lawsuit concerning an alleged infringement of one of his Patents for the improvement of the Compass. Airy declined to make an affidavit or to take sides in the dispute, but he wrote a letter from which the following is extracted: "I cannot have the least difficulty in expressing my opinion that you have made a great advance in the application of my method of correcting the compass in iron ships, by your introduction of the use of short needles for the compass-cards. In my original investigations, when the whole subject was in darkness, I could only use existing means for experiment, namely the long-needle compasses then existing. But when I applied mechanical theory to explanation of the results, I felt grievously the deficiency of a theory and the construction which it suggested (necessarily founded on assumption that the proportion of the needle-length to the other elements of measure is small) when the length of the needles was really so great. I should possibly have used some construction like yours, but the Government had not then a single iron vessel, and did not seem disposed to urge the enquiry. You, under happier auspices, have successfully carried it out, and, I fully believe, with much advantage to the science."—He wrote a Paper for the Athenaeum and had various correspondence on the subject of the Badbury Rings in Dorsetshire, which he (and others) considered as identical with the "Mons Badonicus" of Gildas, the site of an ancient British battle.—In February he was in correspondence with the Astronomer Royal on Uniform Time Reckoning, and on considerations relating to it.—On June 6th he attended the Annual Visitation of the Observatory, and brought before the Board his investigations of the Diurnal Magnetic Inequalities, and the revises of his Lunar Theory.

1886

From June 8th to July 17th he was at Playford.—And again at Playford from Oct. 5th to Nov. 8th.—On March 27th he had an attack of gout in his right foot, which continued through April and into May, causing him much inconvenience.—He was busy with the Numerical Lunar Theory up to Sept. 25th, when he was reading the last proof-sheet received from the printers: during this period his powers were evidently failing, and there are frequent references to errors discovered and corrected, and to uncertainties connected with points of the Theory. But his great work on the Numerical Lunar Theory was printed in this year: and there can be no doubt that he experienced a great feeling of relief when this was accomplished.—He was in correspondence with Prof. Adams as to the effect of his reduction of the Coefficient of Lunar Acceleration on the calculation of the ancient historical eclipses.—He compiled a Paper "On the establishment of the Roman dominion in England," which was printed in 1887.—He wrote a notice concerning events in the life of Mr John Jackson of Rosthwaite near Keswick, a well-known guide and much-respected authority on matters relating to the Lake District.—He also wrote a short account of the connection of the history of Mdlle de Quéroualle with that of the Royal Observatory at Greenwich.—On June 4th he attended at the Annual Visitation of the Observatory.

1887

On May 9th to 11th he made a short visit to Eastbourne and the neighbourhood.—From June 8th to July 13th he was at Playford.—From Aug. 29th to Sept. 5th he was travelling in Dorsetshire and Wiltshire: he went first to Weymouth, a very favourite centre for excursions with him, and afterwards visited Bridport and Lyme Regis: then by Dorchester to Blandford, and visited the Hod Hill, Badbury Rings, &c.: at Wimborne he was much interested in the architecture of the church: lastly he visited Salisbury, Old Sarum, Stonehenge, &c., and returned to Greenwich.—From Oct. 11th to Nov. 12th he was at Playford.—During this year he partly occupied himself with arranging his papers and drawings, and with miscellaneous reading. But he could not withdraw his thoughts from his Lunar Theory, and he still continued to struggle with the difficulties of the subject, and was constantly scheming improvements. His private accounts also now gave him much trouble. Throughout his life he had been accustomed to keep his accounts by double entry in very perfect order. But he now began to make mistakes and to grow confused, and this distressed him greatly. It never seemed to occur to him to abandon his elaborate system of accounts, and to content himself with simple entries of receipts and expenses. This would have been utterly opposed to his sense of order, which was now more than ever the ruling principle of his mind. And so he struggled with his accounts as he did with his Lunar Theory till his powers absolutely failed. In his Journal for this year there are various entries of mental attacks of short duration and other ailments ascribable to his advanced age.

The last printed "Papers by G.B. Airy" belong to this year. One was the Paper before referred to "On the establishment of the Roman dominion in England": another was on the solution of a certain Equation: and there were early reminiscences of the Cambridge Tripos, &c.—In February he attended a little to a new edition of his Ipswich Lectures, but soon handed it over to Mr H.H. Turner of the Royal Observatory.—On May 23rd he was drawing up suggestions for the arrangement of the Seckford School, &c., at Woodbridge.—On June 4th he attended the Visitation of the Royal Observatory, when a resolution was passed in favour of complete photography of the star-sky.

1888

From the 14th to 16th of May he made a short expedition to Bournemouth, and stopped on the way home to visit Winchester Cathedral.—From June 27th to Aug. 3rd he was at Playford; and again from Oct. 13th to Nov. 10th.—During the first half of the year he continued his examination of his Lunar Theory, but gradually dropped it. There are several references in his Journal to his feelings of pain and weakness, both mental and bodily: at the end of March he had an attack of gout in the fingers of his right hand. During the latter part of the year he was troubled with his private accounts, as before.—He does not appear to have been engaged on any miscellaneous matters calling for special notice in this year. But he kept up his astronomical correspondence—with Lockyer on the meteorite system of planetary formation; with Pritchard on the work of the Oxford University Observatory; with Adams on his Numerical Lunar Theory, &c., and with others.—On June 2nd he attended the Visitation of the Royal Observatory.—He amused himself occasionally with reading his favourite subjects of history and antiquities, and with looking over some of his early investigations of scientific questions.

1889

On June 5th he made a one-day's excursion to Colchester.—From July 2nd to 27th he was in the Cumberland Lake District, chiefly at Portinscale near Keswick. While staying at Portinscale he was seized with a sudden giddiness and fell upon the floor: he afterwards wrote a curious account of the visions which oppressed his brain immediately after the accident. He returned by Solihull, where his son Osmund was residing.—From Oct. 4th to Nov. 8th he was at Playford. While there he drew up a short statement of his general state of health, adverting particularly to the loss of strength in his legs and failure of his walking powers.—His health seems to have failed a good deal in this year: on Feb. 4th he had an accidental fall, and there are several entries in his Journal of mental attacks, pains in his limbs, affection of his eye-sight, &c.—In the early part of the year he was much engaged on the history of the Airy family, particularly on that of his father.—In this year the White House was sold by auction by its owners, and Airy purchased it on May 24th.—He was still in difficulties with his private accounts, but was making efforts to abandon his old and elaborate system.—For his amusement he was chiefly engaged on Theological Notes which he was compiling: and also on early optical investigations, &c.

On June 1st he attended the Visitation of the Royal Observatory, and moved a resolution that a Committee be appointed to consider whether any reduction can be effected in the amount of matter printed in the Volume of Observations of the Royal Observatory. During his tenure of office he had on various occasions brought this subject before the Board of Visitors, and with his usual tenacity of purpose he now as Visitor pressed it upon their notice.—In May he zealously joined with others in an application to get for Dr Huggins a pension on the Civil List.—In January he prepared a short Paper illustrated with diagrams to exhibit the Interference of Solar Light, as used by him in his Lectures at Cambridge in 1836: but it does not appear to have been published.—In April he received a copy of a Paper by Mr Rundell, referring to the complete adoption of his system of compass correction in iron ships, not only in the merchant service, but also in the Navy. This was a matter of peculiar gratification to Airy, who had always maintained that the method of Tables of Errors, which had been so persistently adhered to by the Admiralty, was a mistake, and that sooner or later they would find it necessary to adopt his method of mechanical correction. The passage referred to is as follows: "The name of Sir George Airy, the father of the mechanical compensation of the compass in iron vessels, having just been mentioned, it may not be inappropriate to remind you that the present year is the fiftieth since Sir George Airy presented to the Royal Society his celebrated paper on this subject with the account of his experiments on the 'Rainbow' and 'Ironsides.' Fifty years is a long period in one man's history, and Sir George Airy may well be proud in looking back over this period to see how complete has been the success of his compass investigation. His mode of compensation has been adopted by all the civilized world. Sir William Thomson, one of the latest and perhaps the most successful of modern compass adjusters, when he exhibited his apparatus in 1878 before a distinguished meeting in London, remarked that within the last ten years the application of Sir George Airy's method had become universal, not only in the merchant service, but in the navies of this and other countries, and added—The compass and the binnacles before you are designed to thoroughly carry out in practical navigation the Astronomer Royal's principles."

1890

From May 17th to 24th he was on an expedition to North Wales, stopping at Chester, Conway, Carnarvon, Barmouth, and Shrewsbury.—From June 18th to July 24th he was at Playford; and again from Oct. 11th to Nov. 15th.—In this year his powers greatly failed, and he complained frequently of mental attacks, weakness of limbs, lassitude, and failure of sleep. He occupied himself as usual with his books, papers, and accounts; and read Travels, Biblical History, &c., but nothing very persistently.

On June 7th he attended the Visitation of the Royal Observatory.—From a letter addressed to him by Mr J. Hartnup, of Liverpool Observatory, it appears that there had grown up in the mercantile world an impression that very accurate chronometers were not needed for steam ships, because they were rarely running many days out of sight of land: and Airy's opinion was requested on this matter. He replied as follows on Mar. 3rd: "The question proposed in your letter is purely a practical one. (1) If a ship is likely ever to be two days out of sight of land, I think that she ought to be furnished with two good chronometers, properly tested. (2) For the proper testing of the rates of the chronometers, a rating of the chronometers for three or four days in a meridional observatory is necessary. A longer testing is desirable."—In March he was in correspondence, as one of the Trustees of the Sheepshanks Fund, with the Master of Trinity relative to grants from the Fund for Cambridge Observatory.

1891

From June 16th to July 15th he was at Playford. And again from Oct. 12th to Dec. 2nd (his last visit). Throughout the year his weakness, both of brain power and muscular power, had been gradually increasing, and during this stay at Playford, on Nov. 11th, he fell down in his bed-room (probably from failure of nerve action) and was much prostrated by the shock. For several days he remained in a semi-unconscious condition, and although he rallied, yet he continued very weak, and it was not until Dec. 2nd that he could be removed to the White House. Up to the time of his fall he had been able to take frequent drives and even short walks in the neighbourhood that he was so fond of, but he could take but little exercise afterwards, and on or about Nov. 18th he made the following note: "The saddest expedition that I have ever made. We have not left home for several days."

The rapid failure of his powers during this year is well exemplified by his handwriting in his Journal entries, which, with occasional rallies, becomes broken and in places almost illegible. He makes frequent reference to his decline in strength and brain-power, and to his failing memory, but he continued his ordinary occupations, made frequent drives around Blackheath, and amused himself with his family history researches, arrangement of papers, and miscellaneous reading: and he persisted to the last with his private accounts. His interest in matters around him was still keen. On June 13th he was driving along the Greenwich Marshes in order to track the course of the great sewer; and on August 5th he visited the Crossness Sewage Works and took great interest in the details of the treatment of the sewage.—In March he contributed, with great satisfaction, to the Fund for the Portrait of his old friend Sir G.G. Stokes, with whom he had had so much scientific correspondence.—On July 25th an afternoon party was arranged to celebrate the 90th anniversary of his birthday (the actual anniversary was on July 27th). None of his early friends were there: he had survived them all. But invitations were sent to all his scientific and private friends who could be expected to come, and a large party assembled. The afternoon was very fine, and he sat in the garden and received his friends (many of whom had come from long distances) in good strength and spirits. It was a most successful gathering and was not without its meaning; for it was felt that, under the circumstances of his failing powers, it was in all probability a final leave-taking.—On July 27th he went down to the Greenwich Parish Church at 9 p.m., to be present at the illumination of the church clock face for the first time—a matter of local interest which had necessitated a good deal of time and money. On this occasion at the request of the company assembled in and around the Vestry he spoke for about a quarter of an hour on Time—the value of accurate time, the dissemination of Greenwich time throughout the country by time-signals from the Observatory, and the exhibition of it by time-balls, &c., &c.,—the subject to which so large a part of his life had been devoted. It was a pleasant and able speech and gave great satisfaction to the parishioners, amongst whom he had lived for so many years.—He received two illuminated addresses—one from the Astronomer Royal and Staff of the Royal Observatory; the other from the Vorstand of the Astronomische Gesellschaft at Berlin—and various private letters of congratulation. The address from the Staff of the Observatory was worded thus: "We, the present members of the Staff of the Royal Observatory, Greenwich, beg to offer you our most sincere congratulations on the occasion of your 90th birthday. We cannot but feel how closely associated we are with you, in that our whole energies are directed to the maintenance and development of that practical astronomical work, of which you essentially laid the foundation. It affords us great pleasure to think that after the conclusion of your life's work, you have been spared to live so long under the shadow of the noble Observatory with which your name was identified for half a century, and with which it must ever remain associated."

After his return from Playford he seemed to rally a little: but he soon fell ill and was found to be suffering from hernia. This necessitated a surgical operation, which was successfully performed on Dec. 17th. This gave him effectual relief, and after recovering from the immediate effects of the operation, he lay for several days quietly and without active pain reciting the English poetry with which his memory was stored. But the shock was too great for his enfeebled condition, and he died peacefully in the presence of his six surviving children on Jan. 2nd, 1892. He was buried in Playford churchyard on Jan. 7th. The funeral procession was attended at Greenwich by the whole staff of the Royal Observatory, and by other friends, and at his burial there were present two former Fellows of the College to which he had been so deeply attached.