Autobiography of Sir George Biddell Airy by George Biddell Airy (primary phonics books .TXT) 📖

of light in the best practical experiment (that of the flat prism); and I went thoroughly into the main points of the Undulatory Theory, interference, diffraction, &c. In 1830 I believe I went (in addition to what is mentioned above) into Polarization and Depolarization of all kinds. My best lecture diagrams were drawn and painted by my wife. The Lectures were universally pronounced to be valuable. The subjects underwent no material change in 1831, 2, 3, 4, 5; and I believe it was a matter of sincere regret to many persons that my removal to Greenwich terminated the series. Each lecture nominally occupied an hour. But I always encouraged students to stop and talk with me; and this supplement was usually considered a valuable part of the lecture. Practically the lecture, on most days, occupied two hours. I enjoyed the Lectures much: yet I felt that the labour (in addition to other work) made an impression on my strength, and I became at length desirous of terminating them.

"The Observatory, when I took charge of it, had only one instrument--the Transit-Instrument The principles however which I laid down for my own direction were adapted to the expected complete equipment, Planets (totally neglected at Greenwich) were to be observed. Observations were to be reduced completely, and the reductions were to be exhibited in an orderly way: this was a novelty in Astronomy. I considered it so important that I actually proposed to omit in my publication the original observations, but was dissuaded by Herschel and others. I sometimes suspended, observations for a short time, in order to obtain leisure for; the reductions. I had at first no intention of correcting the places of the fundamental stars as settled at Greenwich. But I found myself compelled to do so, because they were not sufficiently accurate; and then I took the course of observing and reducing as an independent observer, without reference to any other observatory. I introduced the principle of not correcting instrumental errors, but measuring them and applying numerical corrections. I determined my longitude by chronometers, and my latitude by a repeating circle borrowed from Mr Sheepshanks, which I used so well that the result; was only half a second in error. The form of my reductions in the published volume for 1828 is rather irregular, but the matter is good: it soon attracted attention. In 1829 the process was much the same: I had an assistant, Mr Baldrey. In 1830 still the same, with the additions:--that I formally gave the corrections of relative right-ascension of fundamental stars (without alteration of equinox, which I had not the means of obtaining) to be used in the year 1831; and that I reduced completely the observed occultations (with a small error, subsequently corrected). In 1831 the system of correction of broken transits was improved: the errors of assumed R.A. of Fundamental Stars were exhibited: Mean Solar Time was obtained from Sidereal Time by time of Transit of [Symbol: Aries] (computed by myself): the method of computing occultations was improved. In 1832 the small Equatoreal was erected, and was soon employed in observations of the elongation of the 4th Satellite of Jupiter for determining the mass of Jupiter. The Mural Circle was erected at the end of the year, but not used. The calculation of R.A. of Fundamental Stars was made homogeneously with the others: separate results of all were included in ledgers: a star-catalogue was formed: all as to the present time (1871). With the Equatoreal the difference of N.P.D. of Mars and stars was observed.

"With the beginning of 1833 the Mural Circle was established at work, a second assistant (Mr Glaisher) was appointed, and the Observatory might be considered complete. I made experiments on the graduations of the Circle. I detected and was annoyed by the R--D. I determined the latitude. I exhibited the separate results for N.P.D. of stars in ledger, and their means in Catalogue. I investigated from my observations the place of equinox and the obliquity of the ecliptic. I made another series of observations of Jupiter's 4th Satellite, for the mass of Jupiter. I observed the solar eclipse with the Equatoreal, by a method then first introduced, which I have since used several times at Cambridge and Greenwich with excellent effect. The Moon and the Planets were usually observed till near two in the morning. Correction for defective illumination applied when necessary. The volume is very complete, the only deficiency being in the observation of Moon and Planets through the severe morning hours. In 1834 the only novelties are--examination of the graduations of the declination circle of the Equatoreal (excessively bad): observations of a spot on Jupiter for rotation, and of Mars and stars. In 1835 (including January 1836) there is a more complete examination of the Equatoreal graduations: parallax and refraction for Equatoreal observations: a spot on Jupiter: a series of observations on Jupiter's 4th Satellite for the mass of Jupiter: Mars and stars: Halley's Comet (the best series of observations which could be made in the season): and a short series of meteorological observations, on a plan suggested by Sir John Herschel then at the Cape of Good Hope.

"I cannot tell precisely in which year I introduced the following useful custom. Towards the end of each year I procured a pocket-book for the following year with a space for every day, and carefully examining all the sources of elements of observations, and determining the observations to be made every day, I inserted them in the pocket-book. This system gave wonderful steadiness to the plan of observations for the next year. The system has been maintained in great perfection at the Observatory of Greenwich. (The first of these pocket-books which Prof. Adams has found is that for 1833.) Printed skeleton forms were introduced for all calculations from 1828. In the Greenwich Observatory Library there is a collection, I believe complete, of printed papers commencing with my manifesto, and containing all Syndicate Reports except for 1833 (when perhaps there was none). It seems from these that my first written Report on Observations, &c., was on May 30th, 1834. The first Syndicate Report is on May 25th, 1829."

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A few remarks on Airy's private life and friends during his residence at Cambridge Observatory may be here appropriately inserted.

Amid the laborious occupations recorded in the foregoing pages, his social life and surroundings appear to have been most pleasant and congenial. At that period there were in residence in Cambridge, and particularly at Trinity, a large number of very brilliant men. Airy was essentially a Cambridge man. He had come up poor and friendless: he had gained friends and fame at the University, and his whole work had been done there. From the frequent references in after times both by him and his wife to their life at Cambridge, it is clear that they had a very pleasant recollection of it, and that the social gatherings there were remarkably attractive. He has himself recorded that with Whewell and Sedgwick, and his accomplished sisters-in-law, who were frequently on long visits at the Observatory, they formed pretty nearly one family.

His friendship with Whewell was very close. Although Whewell was at times hasty, and rough-mannered, and even extremely rude, yet he was generous and large-minded, and thoroughly upright. [Footnote: The following passage occurs in a letter from Airy to his wife, dated 1845, Sept. 17th: "I am sorry that ---- speaks in such terms of the 'Grand Master,' as she used to be so proud of him: it is only those who have well gone through the ordeal of quarrels with him and almost insults from him, like Sheepshanks and me, that thoroughly appreciate the good that is in him: I am sure he will never want a good word from me."] In power of mind, in pursuits, and interests, Airy had more in common with Whewell than with any other of his friends. It was with Whewell that he undertook the experiments at Dolcoath: it was to Whewell that he first communicated the result of his remarkable investigation of the Long Inequality of Venus and the Earth; and some of his Optical researches were conducted jointly with Whewell. Whewell took his degree in 1816, seven years before Airy, and his reputation, both for mathematical and all-round knowledge, was extremely and deservedly great, but he was always most generous in his recognition of Airy's powers. Thus in a letter of Mar. 16th, 1823 (Life of William Whewell by Mrs Stair Douglas), he says, "Airy is certainly a most extraordinary man, and deserves everything that can be said of him"; and again in the autumn of 1826 he writes to his aunt, "You mentioned a difficulty which had occurred to you in one of your late letters; how Airy should be made Professor while I was here, who, being your nephew, must of course, on that account, deserve it better than he could. Now it is a thing which you will think odd, but it is nevertheless true, that Airy is a better mathematician than your nephew, and has moreover been much more employed of late in such studies.... Seriously speaking, Airy is by very much the best person they could have chosen for the situation, and few things have given me so much pleasure as his election." How much Whewell depended upon his friends at the Observatory may be gathered from a letter which he wrote to his sister on Dec. 21st, 1833. "We have lately been in alarm here on the subject of illness. Two very near friends of mine, Prof. and Mrs Airy, have had the scarlet fever at the same time; she more slightly, he very severely. They are now, I am thankful to say, doing well and recovering rapidly. You will recollect that I was staying with them at her father's in Derbyshire in the summer. They are, I think, two of the most admirable and delightful persons that the world contains." And again on Dec. 20th, 1835, he wrote to his sister Ann, "My friends--I may almost say my dearest friends --Professor Airy and his family have left Cambridge, he being appointed Astronomer Royal at Greenwich--to me an irreparable loss; but I shall probably go and see how they look in their new abode." Their close intercourse was naturally interrupted by Airy's removal to Greenwich, but their friendly feelings and mutual respect continued without material break till Whewell's death. There was frequent correspondence between them, especially on matters connected with the conduct and teaching of the University, in which they both took a keen interest, and a warm welcome at Trinity Lodge always awaited Mr and Mrs Airy when they visited Cambridge. In a letter written to Mrs Stair Douglas on Feb. 11th, 1882, enclosing some of Whewell's letters, there occurs the following passage: "After the decease of Mrs Whewell, Whewell wrote to my wife a mournful letter, telling her of his melancholy state, and asking her to visit him at the Lodge for a few days. And she did go, and did the honours of the house for several days. You will gather from this the relation in which the families stood." Whewell died on Mar. 6th, 1866, from the effects of a fall from his horse, and the following extract is from a letter written by Airy to Whewell's niece, Mrs Sumner Gibson, on hearing of the death of his old friend:

"The Master was, I believe, my oldest surviving friend (beyond my own family), and, after an acquaintance of 46 years, I must have been one of his oldest friends. We have during that time been connected privately and officially: we travelled together and experimented