xliv REPORT — 1853. 



the other as seeu 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 external boundary, and how entirely the characteristic details of 

 the larger drawings are lost in the smaller ones ; and if I had exhibited to you 

 drawings of some others of these nebulae, 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 de- 

 velopment of the real character of these astonishing and enigmatical aggre- 

 gations 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 18^ inches aperture. It is now proposed to send 

 out to some convenient station in the southern hemisphere a reflecting tele- 

 scope, with a mirror of 4- feet aperture. Mr. Grubb, of Dublin, has under- 

 taken to construct such an instrument (should the plan proposed be adopted) 

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

 and one or two other gentlemen. The general construction of the instrument, 

 and the best mode of mounting it, have been decided on with careful delibe- 

 ration, after consulting all the best authorities on the subject. 



These important preliminaries being agreed upon, and an estimate of the 

 whole expense of the instrument having been made by Mr. Grubb, the depu- 

 tation appointed for the purpose 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 deputation could not be otherwise 

 than perfectly satisfied, nor could they fail also to be gratified by the perfect 

 courtesy with which they were received. Judging from ail we know respecting 

 Mr. Gladstone's enlightened views on subjects of tiiis nature, and the favour- 

 able manner in which the House of Commons has always received proposi- 

 tions for the advancement of science, we have, I tiiink, every reason to hope 

 that my successor in this Chair may have the satisfaction of announcing to 

 you another instance of the liberality of the Government in their acceptance of 

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

 another proof that the Association is doing effectively what it professes to do 

 as an Association for tlie Advancement of Science. 



The refinement of modern methods of astronomical observation has be- 

 come so great, that astronomers 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 

 important researches of tliis kind. He has corrected an error in Burckhardt's 

 value of the moon's parallax ; and he has also determined to a nearer approxi- 

 mation than that obtained by Laplace, the secular variation in the moon's 

 mean motion. The former investigation is published in an Appendix to the 

 Nautical Almanac for 1856; the latter has been very recently presented to 

 the Royal Society. 



Before I quit this subject, I may state that an ' American Epbemeris and 



