80 



MEETING OF THE BRITISH ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE. [1853 



subjected. Tims, while the latter obey, in common with the 

 planets, the laws of gravitation, they frequently present to us, in 

 their apparent changes of volume, form and general character, 

 phenomena, the explanation of which has hitherto baffled the 

 ingenuity of astronomers. One of the most curious of these 

 phenomena has been recently observed in Biela's comet This 

 comet has a period of about six years and a half, and has been 

 observed a considerable number of times on its pe.iodical return 

 to the neighbourhood of the sun. It appeared in November, 

 1845, and in the following January, the phenomenon alluded to 

 ■was observed for the first time. The comet had become t'.ivided 

 into two distinct parts with separate nuclei. Sometimes the one 

 and sometimes the other appeared the brighter, till their final 

 disappearance. The elements of the orbits of these twin comets 

 were calulated by Professor Plantamour, from observations made 

 at Geneva in 1845-6, assuming them to be uninfluenced by each 

 other's attractions. The correctness of these elements could be 

 determined only on the next return of the comet, which took 

 place in the autumn of last year, one of the nuclei having been 

 first seen by Signor Secchi at Rome, on the 25th ot August, and 

 the other on the 15th of September. The subsequent observa- 

 tions made upon them show that the elements of the orbits, as 

 previously calculated from the Geneva observations, weie far from 

 exact. A complete discussion of all the observations which have 

 been made on these comets during their last and previous appear- 

 ances, is now in progress by Professor Hubbard, of the Washing- 

 ton Observatory. The distance between the two nuclei was much 

 increased on their last appearance. Judging from the apparent 

 absence of all influence and sympathy between these bodies, it 

 would seem that their physical divorcement, though without 

 known precedent, is final and complete. 



Stellar Astronomy continues to manifest a vigour and activity 

 worthy of the lofty interest which attaches to" it. Bessel had 

 made a survey of all stars to those of the ninth magnitude inclu- 

 sive, in a zone lying between 45- of north, and 15 : of south 

 declination. Argelander has extended this zone from 80 : of 

 north, to 31 ° of south declination. It comprises more than 

 100,000 stars. Last year was published also the long expected 

 work of M. F. G. W. Struve, containing a catalogue of stars ob- 

 served by him at Dorpat, in the years 1822 — 43." They are prin- 

 cipally double and multiple stare, which had been previously 

 micrometrically observed by the same distinguished astronomer. 

 Thefr number amounts to 2874; the epoch of reduction is 1830. 

 The introduction contains the discussion of various important 

 points in stellar astronomy. 



Notices have been brought before us from time to time, of the 

 nebulae observed through Lord Rosse's telescope. This noble 

 instrument, so unrivalled for observations of this kind, continues 

 to be applied to the same purpose, and to add yearly to our 

 knowledge of the remotest regions of space into wdiich the eye of 

 man has been able to penetrate. Almost every new observation 

 appears to confirm the fact of that curious teudency to a spiral 

 arrangement in these nebulous masses of which mention has so 

 frequently been made. To those persons, however, who have 

 neither seen the objects themselves, nor careful drawings of them, 

 a mere verbal description must convey very indistinct conceptions 

 of the spiral forms which they assume. I have, therefore had the 

 drawings made which are suspended in the room for your inspec- 

 tion. They will convey to you at once an idea of the spiral forms 

 alluded to. I am indebted to the kindness of Lord Rosse for the 

 use of the original drawings, — and for these large and accurate 

 copies of them, to our excellent Secretary, Mr. Phillips, who, with 

 his usual activity in the cause of the Association, has had them 

 prepared for the purpose of this evening. Most of them are 

 representations of nebulae which have been very recently observed. 



Two pairs of these are respectively drawings of the same ob- 

 jects; the larger one of each pair representing the nebula as seen 

 through the large telescope, the other as seen through a smaller 

 one of Lord Rosse's, of only three feet aperture. You will observe 

 how little resemblance there is between them, except in the exter- 

 nal boundary, and how entirely the characteristic details of the 

 larger drawings are lost in the smaller ones ; and if I had exhibit- 

 ed to you drawings of some others of these nebulas, as seen by 

 previous observers with inferior telescopic power, it would have 

 been still more obvious to you how necessary are telescopes with 

 large and perfectly ground mirrors for the development of the 

 real character of these astonishing and enigmatical aggregations 

 of stars. 



It is for this reason that it has been thought desirable to have 

 the nebulae of the southern hemisphere examined with higher 

 telescopic power than has hitherto been brought to bear upon 

 them. You are aware with what a noble devotion to science Sir 

 J. Herschel spent several years at the Cape of Good Hope, in the 

 examination of the southern heavens; but his telescopic power 

 was limited to that of a reflector of l&j inches aperture. • It is 

 now proposed to send out to some convenient station in the 

 southern hemisphere a reflecting telescope, with a mirror of four 

 feet aperture. Mr. Grubb, of Dublin, has undertaken to construct 

 such an instrument, (sin add the plan proposed be adopted,) under 

 the general superintendence of Lord Rosse, Dr. Robinson, Mr. 

 Lassel, ami one or two other gentlemen. The general construc- 

 tion of the instrument, and the best mode of mounting it, have 

 been decided on with careful deliberation, after consulting all the 

 best authorities on the subject. 



These important preliminaries being agreed upon, and an esti- 

 mate of the whole expense of the instrument having been made 

 by Mr. Grubb, the deputation appointed proceeded to wait on 

 Lord Aberdeen, to ascertain whether the Government were willing 

 to bear the expense which the plan proposed would involve. His 

 Lordship expressed himself, without hesitation, as favourable to 

 the undertaking; but said that, since it involved a grant of money, 

 it would be necessary to consult the Chancellor of the Exchequer, 

 who, supposing him to take a favourable view of the subject, 

 would probably bring it before the House of Commons among 

 the estimates of the ensuing year. With this answer, the depu- 

 tation could not be otherwise than perfectly satisfied, nor could 

 they fail also to be gratified by the perfect courtesy with which 

 the)' were received. Judging from all we know respecting Mr. 

 Gladstone's enlightened views on subjects of this nature, and the 

 favourable manner in which the House of Commons has always 

 received propositions for the advancement of science, we have, I 

 think, every reason to hope that my successor in this chair may 

 have the satisfaction of announcing to you another example of the 

 liberality of the Goverment in their acceptance of the plan pro- 

 posed to them. In such case, the result, I doubt not, will afford 

 a new proof that the association is doing effectively what it pro- 

 fesses to do as an association for the advancement of science. 



The refinement of modern methods of astronomical observa- 

 tion has become so great, that astror.omers appear very generally 

 to think that a higher degree of refinement in the calculations of 

 physical astronomy than has yet been attained is becoming 

 necessary. Mr. Adams has been engaged in some researches of 

 this kind. He has corrected an errror in Burckhardt's value of 

 the moon's parallax ; and he has also determined to a nearer ap- 

 proximation than that obtained bv Laplace the secular variation 

 in the moon's mean motion. The former investigation is pub- 

 lished in an appendix to the Nautical Almanac for 1856; the 

 latter has been very recently presented to the Royal Soeietv. 



Before I quit this subject, I may state, that an American 'Ephe- 

 meris and Nautical Almanac for 1855 ' has been published this 



