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534° at 3h. 15m. P.M. to 46° by 4h. P.M., and to 43° by 5h. P.M.); and the direction of the wind immediately changed to the amount of 90°, following the direction of the sun, or from S.S.W. to W.N.W.

At the Radcliffe Observatory, Oxford, the barometer-reading at 6h. A.M. was 29.18 in., and decreased to 28.80 in. at 2h. 30m.; it then suddenly increased to 28.85 in. at 2h. 35m., and to 29.25 in. by 11h. P.M. At 2h. the direction of the wind was S. ; at 3h. 30m. it was W., and continued W. till 4h. 30m., and then returned to S.W. by 5h. The temperature at 2h. was 51°, declined to 43° at 2h. 30m., and to 41° by 5h.

The general changes of temperature agree very closely with those at Greenwich; but, as in the case of the barometer, those at Oxford preceded those at Greenwich by one hour nearly.

The general fact frequently noticed of a change in the direction of the wind simultaneously with a sudden and great pressure, and for the most part in one direction (that is to say, in the direction of the sun's motion, or N. to E. to S.), is very remarkable, and not easily accounted for.

November 30, 1863.

ANNIVERSARY MEETING.

Major-General SABINE, President, in the Chair.

Dr. Alderson, on the part of the Auditors of the Treasurer's Accounts, reported that the total receipts during the past year, including a balance of £635 78. 3d. carried from the preceding year, amounted to £5133 10s. 3d., and that the total expenditure in the same period amounted to £4475 10s. 2d., leaving a balance at the Bank of £641 14s., and in the hands of the Treasurer of £16 6s. 1d.

On the motion of Sir Andrew S. Waugh, seconded by Mr. Hudson, the thanks of the Society were voted to the Treasurer and Auditors.

The Secretary read the following Lists :

Fellows deceased since the last Anniversary.

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The PRESIDENT then addressed the Society as follows:

:

GENTLEMEN, WHEN I had last the honour of addressing you at the Anniversary Meeting in 1862, I acquainted you that a communication had been received by your President and Council from the Duke of Newcastle, Her Majesty's principal Secretary of State for the Colonies, requesting the opinion of the Royal Society on the scientific importance of the results to be expected from the establishment of a Telescope of great optical power at Melbourne, in the Colony of Victoria, for the observation of the nebula and multiple stars of the Southern Hemisphere. The communication was founded on a despatch from Sir Henry Barkly, K.C.B., Governor of Victoria, soliciting on his own part and on that of the Visitors of the Melbourne

Observatory, the opinion of the Royal Society on this subject, and also on the most suitable construction of the telescope, both as to the optical part and the mounting, its probable cost, and the time required for its completion. It had happened that in 1853 the Royal Society and the British Association had united in an earnest representation to Her Majesty's Government of the scientific importance of establishing in some convenient locality in Her Majesty's dominions, from whence the southern nebulæ and multiple stars could be observed, a telescope of the requisite optical power; and in a preparatory correspondence, which was printed at the time, and in which the principal persons interested in such researches had participated, the best form of telescope, its probable cost, and all particulars relating to it, had been largely discussed. The representation thus concurred in by the two principal scientific bodies of the United Kingdom was not successful in securing the desired object; but the correspondence then printed was still fitted to supply in great measure in 1862 the information on which the President and Council could ground their reply. The discussion in 1853 had terminated in the appointment of a committee, consisting of the Earl of Rosse, Dr. Robinson, and Messrs. Lassell and Warren de la Rue, to superintend the construction of the telescope, in the event of the recommendation of the two Societies being favourably received. But as it was possible that the opinions previously entertained might have been in some degree modified by subsequent consideration or by more recent experience, the correspondence with those gentlemen was reopened, and their replies have formed a second correspondence, which, like the first, has been printed for the information of those Fellows of the Society who take a special interest in the subject. Availing themselves of these valuable communications, the President and Council replied to the Colonial Office by a report dated December 18, 1862. They have been since informed that copies of the report and of the correspondence have been sent to Melbourne for the information of the gentlemen with whom the proposition originated.

It is quite possible that the thoughtful discussions embodied in the correspondence referred to may be found to have a prospective value not limited to the occasion which has given rise to them. The considerations which apply to a telescope for the observation of the Southern Nebula at Melbourne are no less applicable to one which might be established on a site from whence a great part of the Southern Nebulæ could also be observed (as well as those of our own hemisphere), but enjoying the immense advantage conferred by elevation into the higher and less dense strata of the atmosphere. Such sites are to be found in the Nilgiris at elevations of several thousand feet, combining also convenient accessibility and proximity to the resources of civilized life. It may be hoped that at some not distant day the subject will receive the consideration which it deserves from those who are entrusted with the government of that now integral part of the British empire.

Having learnt that a series of pendulum experiments at the principal stations of the Great Russian Arc were in contemplation, I availed myself of an opportunity of informing M. Savitsch, by whom the operations were to be conducted, that the Invariable Pendulums which had been employed in the English experiments were now in the possession of the Royal Society, and, being unemployed, would, I was persuaded, be most readily lent by the Society on an application to that effect being made. The constants of these instruments, including the coefficient in the reduction to a vacuum, having been most carefully determined, they were ready, with the clocks and stands belonging to them, for immediate use, and would have the further advantage, that experiments made with them in Russia would be at once brought into direct connexion with the British series extending from 79° 50' N. to 62° 56', S. latitude. The communication was most courteously received and replied to. It appeared, however, that a detached invariable pendulum had been already ordered by the Russian Government from M. Repsold, of Hamburg, shorter than the English pendulums for convenience in land transport, and with two knife-edges and two fixed lenses, symmetrical in size and shape but one light and the other heavy, and so arranged that the times of vibration should be the same on either knife-edge in air of the same temperature and density. M. Savitsch expressed his desire to bring this pendulum in the first instance to Kew, and to secure thereby the connexion of his own with the English series, where also he would have the opportunity of testing the exactness of the correction for buoyancy by vibrating his pendulum on both its knife-edges in the vacuum-apparatus which is now established at Kew.

It is much to be desired that a similar series of pendulum experiments to those about to be undertaken in Russia should be made at the principal points of the Great Indian Arc; and the steps which are understood to be in progress in providimg new instruments for the verification of the astronomical and geodesical operations of the Trigonometrical Survey of India, and to give them a still greater extension, would seem to present a most favourable opportunity for the combination of pendulum experiments. In such case the pendulums of the Royal Society might be made available with excellent effect.

The large size of our printed volumes in the present year gives no unfavourable and, I think, no unfair idea of the present scientific activity of the Society; for I believe it may be safely said that our Council has not been less vigilant and cautious than heretofore in the selection of the papers to be printed. Although much care has been given to keeping the expenses of illustration within reasonable bounds, the cost of the Society's publications has been this year unusually high; yet I am glad to be able to state that our whole expenditure within the year has fallen within our income. With your permission, I will briefly advert to a few of the subjects which have occupied the Society's attention in the past year.

The researches of Kirchhoff and Bunsen have rendered it in a high degree probable that we shall be able to obtain much insight into the chemical nature of the atmospheres of the brighter fixed stars, by observing the dark lines in their spectra and comparing them with the bright lines in the spectra of elementary, and perhaps also of compound, bodies in the state of incandescent gas or vapour. The interest of such an inquiry is obvious; but the difficulties involved in it are very great. The quantity of light coming from even such a star as Sirius is so small, that without the use of a powerful telescope the spectrum obtained would be too faint to bear sufficient enlargement to show properly the fixed lines. The apparent diurnal motion of the stars causes much embarrassment, unless the instrument be mounted equatoreally, and furnished with a clock movement. The control of the experiments on incandescent bodies requires a thorough knowledge of chemistry, so as to avoid being misled by impurities in the substances examined, and to be prepared to interpret decompositions or combinations which may take place under unusual circumstances, and which may be manifested only by their effects. Nor can the astronomical and physical parts of the inquiry be well dissociated, so as to be separately undertaken by different individuals; for the most elaborate drawings can hardly convey a faithful idea of the various aspects of the different dark and bright lines, which yet must be borne in mind in instituting a comparison in cases of apparent coincidence. It is fortunate, therefore, that the inquiry has been taken up by two gentlemen working in concert. In a short paper read to the Society on the 26th of last February, and published in the Proceedings, Mr. Huggins and Dr. Miller have described and figured the spectra of three of the brighter stars; and this part of the inquiry will doubtless be continued. In a paper since presented to the Society, Mr. Huggins describes the means employed for practically determining with accuracy the positions of any stellar lines which may be observed, with reference to known points of the spectrum, and has given beautiful maps of the spectra of twenty-four of the elementary bodies under the action of the inductive discharge, reserving others for a future communication. When the inquiry is completed, it is possible that we may obtain an amount of knowledge, respecting the constitution of those distant heavenly bodies, of which we have at present little conception.

Professor Tyndall has given us the fourth of a series of papers upon the relation of Gases and Vapours to Radiant Heat. In the course of these inquiries, he has shown that the different aëriform bodies, even though colourless, exert very different degrees of absorptive action on the rays of heat, and that certain portions of these heat-rays, are more powerfully absorbed than others-rays from objects at a low temperature being more easily absorbed than those from objects at an elevated temperature. He has also proved that gases radiate as well as absorb, and, in conformity

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