In the latter part of 1862 a difference arose between Airy and Major-General Sabine, in consequence of remarks made by the latter at a meeting of the Committee of Recommendations of the British a.s.sociation. These remarks were to the effect "That it is necessary to maintain the complete system of self-registration of magnetic phenomena at the Kew Observatory, because no sufficient system of magnetic record is maintained elsewhere in England"; implying pointedly that the system at the Royal Observatory of Greenwich was insufficient. This matter was taken up very warmly by Airy, and after a short and acrimonious correspondence with Sabine, he issued a private Address to the Visitors, enclosing copies of the correspondence with his remarks, and requesting the Board to take the matter of this attack into their careful consideration. This Address is dated November 1862, and it was followed by another dated January 1863, which contains a careful reply to the various points of General Sabine's attack, and concludes with a distinct statement that he (the Astronomer Royal) can no longer act in confidence with Sabine as a Member of the Board of Visitors.

Of private history: There were the usual short visits to Playford at the beginning and end of the year.--From June 28th to Aug. 5th he was in Scotland (chiefly in the Western Highlands) with his wife and his sons Hubert and Osmund. In the course of this journey he visited the Corryvreckan whirlpool near the island of Scarba, and the following paragraph relating to this expedition is extracted from his journal: "Landed in Black Mile Bay, island of Luing, at 10.30. Here by previous arrangement with Mr A. Brown, agent of the steam-boat company, a 4-oared boat was waiting to take us to Scarba and the Corryvreckan. We were pulled across to the island of Lunga, and rowed along its length, till we came to the first channel opening from the main sea, which the sailors called the Little Gulf. Here the sea was rushing inwards in a manner of which I had no conception. Streams were running with raving speed, sometimes in opposite directions side by side, with high broken-headed billows. Where the streams touched were sometimes great whirls (one not many yards from our boat) that looked as if they would suck anything down. Sometimes among all this were great smooth parts of the sea, still in a whirling trouble, which were surrounded by the mad currents. We seemed entirely powerless among all these."

In the beginning of this year (1862) the Duke of Manchester, in writing to the Rev. W. Airy, had said, "I wish your brother, the Astronomer Royal, could be induced to have investigations made as to whether the aspects of the Planets have any effect on the weather."

This enquiry produced the following reply:

A subject like that of the occult influences of the planets (using the word occult in no bad sense but simply as meaning not _thoroughly_ traced) can be approached in two ways--either by the a priori probability of the existence of such influences, or by the a posteriori evidence of their effects. If the two can be combined, the subject may be considered as claiming the dignity of a science. Even if the effects alone are certain, it may be considered that we have a science of inferior degree, wanting however that definiteness of law and that general plausibility which can only be given when true causes, in accordance with antecedent experience in other cases, can be suggested.

Now in regard to the a priori probability of the existence of planetary influences, I am far from saying that such a thing is impossible. The discoveries of modern philosophy have all tended to shew that there may be many things about us, unknown even to the scientific world, but which well-followed accidents reveal with the most positive certainty. It is known that every beam of light is accompanied by a beam of chemical agency, totally undiscoverable to the senses of light or warmth, but admitting of separation from the luminous and warm rays; and producing photogenic effects. We know that there are disturbances of magnetism going on about us, affecting whole continents at a time, unknown to men in general, but traceable with facility and certainty, and which doubtless affect even our brains and nerves (which are indisputably subject to the influence of magnetism).

Now in the face of these things I will not undertake to say that there is any impossibility, or even any want of plausibility in the supposition that bodies external to the earth may affect us. It may well be cited in its favour that it is certain that the sun affects our magnetism (it is doubtful whether it does so _im_mediately, or mediately by giving different degrees of warmth to different parts of the earth), and it is believed on inferior evidence that the moon also affects it. It may therefore seem not impossible or unplausible that other celestial bodies may affect perhaps others of the powers of nature about us. But there I must stop. The denial of the impossibility is no a.s.sertion of the truth or probability, and I absolutely decline to take either side--either that the influences are real, or that the influences are unreal--till I see evidence of their effects.

Such evidence it is extremely difficult to extract from ordinary facts of observation. I have alluded to the sun's daily disturbance of the magnet as one of the most certain of influences, yet if you were to observe the magnet for a single day or perhaps for several days, you might see no evidence of that influence, so completely is it involved with other disturbances whose causes and laws are totally unknown.

I believe that, in addition to the effects ascribable to Newtonian gravitation (as general motion of the earth, precession of the equinoxes, and tides), this magnetic disturbance is the only one yet established as depending on an external body. Men in general, however, do not think so. It appears to be a law of the human mind, to love to trace an effect to a cause, and to be ready to a.s.sent to any specious cause. Thus all practical men of the lower cla.s.ses, even those whose pecuniary interests are concerned in it, believe firmly in the influence of the moon upon the winds and the weather. I believe that every careful examiner of recorded facts (among whom I place myself as regards the winds) has come to the conclusion that the influence of the moon is not discoverable.

I point out these two things (magnetic disturbances and weather) as tending to shew that notoriety or the a.s.sumed consent of practical men, are of no value. The unnotorious matter may be quite certain, the notorious matter may have no foundation. Everything must stand on its own evidence, as completely digested and examined.

Of such evidence the planetary influence has not a particle.

My intended short note has, in the course of writing, grown up into a discourse of very unreasonable length; and it is possible that a large portion of it has only increased obscurity. At any rate I can add nothing, I believe, which can help to explain more fully my views on this matter.

In this year (1862, June 9th) Airy received the Honorary Degree of LL.D. in the University of Cambridge. He was nominated by the Duke of Devonshire, as appears from the following letter:

LISMORE CASTLE, IRELAND, _April 19th, 1862_.

MY DEAR SIR,

It is proposed according to usage to confer a considerable number of Honorary Degrees on the occasion of my first visit to Cambridge as Chancellor of the University.

I hope that you will allow me to include your name in that portion of the list which I have been invited to draw up.

The ceremony is fixed for the 10th of June.

I am, my dear Sir, Yours very truly, DEVONSHIRE.

_The Astronomer Royal_.

Airy's reply was as follows:

ROYAL OBSERVATORY, GREENWICH, LONDON, S.E.

_1862, April 21_.

MY LORD DUKE,

I am exceedingly gratified by your communication this day received, conveying a proposal which I doubt not is suggested by your Grace's recollection of transactions now many years past.

I have always been desirous of maintaining my connection with my University, and have in various ways interested myself practically in its concerns. It would give me great pleasure to have the connection strengthened in the flattering way which you propose.

I had conceived that alumni of the University were not admissible to honorary degrees; but upon this point the information possessed by your Grace, as Chancellor of the University, cannot be disputed.

I am, my Lord Duke, Your Grace's very faithful servant, G.B. AIRY.

_His Grace The Duke of Devonshire_.

There were in all 19 Honorary Degrees of Doctor of Laws conferred on the 9th of June, including men of such eminence as Armstrong, Faraday, and Fairbairn.

1863

In this year there were several schemes for a Railway through the lower part of Greenwich Park, the most important being the scheme of the London, Chatham and Dover Railway Company. In reference to this scheme the Report to the Visitors states "I may say briefly that I believe that it would be possible to render such a railway innocuous to the Observatory; it would however be under restrictions which might be felt annoying to the authorities of the Railway, but whose relaxation would almost ensure ruin to the Observatory."--"The meridional observations of Mars in the Autumn of 1862 have been compared with those made at the Observatory of Williamstown, near Melbourne, Australia, and they give for mean solar parallax the value 8.932", exceeding the received value by about 1/24th part. (A value nearly identical with this 8.93" has also been found by comparing the Pulkowa and Cape of Good Hope Observations.)"--"The results of the new Dip-Instrument in 1861 and 1862 appear to give a firm foundation for speculations on the state and change of the dip. As a general result, I may state as probable that the value of dip in the middle of 1843 was about 691', and in the middle of 1862 about 6811'. The decrease of dip appears to be more rapid in the second half of this interval than in the first; the dip at beginning of 1853 being about 6844'."--With reference to the re-determination of the longitude of Valencia, it is stated that "The concluded longitude agrees almost exactly with that determined by the transmission of chronometers in 1844; and ent.i.tles us to believe that the longitudes of Kingstown and Liverpool, steps in the chronometer conveyance, were determined with equal accuracy."--"The computations, for inferring the direction and amount of movement of the Solar System in s.p.a.ce from the observed proper motions of 1167 stars, have been completed. The result is, that the Sun is moving towards a point, R.A. 264, N.P.D. 65 (not very different from Sir W. Herschel's, but depending much in N.P.D. on the accuracy of Bradley's quadrant observations), and that its annual motion subtends, at the distance of a star of the first magnitude, the angle 0.4". But the comparison, of the sum of squares of apparent proper motions uncorrected, with the sum of squares of apparent proper motions corrected for motion of Sun, shews so small an advance in the explanation of the star's apparent movements as to throw great doubt on the certainty of results; the sum of squares being diminished by only 1/25th part."--"I had been writing strongly to Maclear on the delays in publishing both the geodetic work and the Star Catalogue at the Cape of Good Hope: he resolves to go on with these works. In December I am still very urgent about the geodesy."

Of private history: There was the usual short visit to Playford at the beginning and end of the year.--"From June 27th to August 10th I was travelling in the North and West of Scotland with my wife, my youngest son Osmund, and my daughter Annot."

In this year the offer of Knighthood (for the third time) was made to Airy through the Rt Hon. Sir George C. Lewis, Bart. The offer was accepted on Feb. 12th, 1863, but on the same day a second letter was written as follows:

_1863, Feb. 12_.

DEAR SIR,

I am extremely ignorant of all matters connected with court ceremonial, and in reference to the proposed Knighthood would ask you:--

1. I trust that there is no expense of fees. To persons like myself of small fortune an honour may sometimes be somewhat dear.

2. My highest social rank is that given by my Academical Degree of D.C.L. which I hold in the Universities of Oxford and Cambridge. In regard to costume, would it be proper that I should appear in the scarlet gown of that degree? or in the ordinary Court Dress?

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

_The Right Honourable Sir George C. Lewis, Bart., &c. &c. &c._

To this letter Sir G.C. Lewis replied that the fees would amount to about _30_, an intimation which produced the following letter:

ROYAL OBSERVATORY, GREENWICH, S.E.

_1863, Feb. 19th_.

DEAR SIR,