ADDRESS. 



xli 



and resolvability of apparently nebulous matter into stars. I do not deny 

 the importance of the last observation ; but as it might be predicted before- 

 hand that the increase in the dimensions of telescopes would lead to more 

 extensive resolution of nebulae, I do not hold the inference* to be by any 

 means certain that all nebulae are resolvable. Mr. Lassell exhibited at the 

 last meeting of the Association a plan for supporting his two-feet mirrors 

 without flexure. This plan, slightly modified, has been adopted in use : and 

 I am assured that the improvement in what before seemed almost perfect 

 definition is very great. The removal of the vexatious fiscal interferences 

 with the manufacture of glass, and the enterprise with which Mr. Chance as 

 manufacturer and Mr. Simms and Mr. Ross as opticians, have taken up the 

 construction of large object-glasses, promise to lead to the most gratifying 

 results. Already Mr. Simms has partially tested object-glasses of 13 inches 

 aperture ; and one of 1 6 inches is waiting not for the flint but for the crown 

 lens. Mr. Ross, it is understood, has ground an object-glass of 2 feet 

 aperture ; but it has not been tested. The facility of procuring large object- 

 glasses will undoubtedly lead to the extensive construction of graduated in- 

 struments on a larger scale than before ; and it is in this view that I contem- 

 plate as a matter of no small importance the erection (this year) of the large 

 transit-circle at the Royal Observatory at Greenwich. It is known to many 

 members of the Association that this instrument was constructed in this town, 

 by Messrs. Ransomes and May ; and for the admirable proportions of its 

 various parts, for the firmness of fitting of the few portions of which it is 

 composed, and for the accuracy of the external forms of pivots, &c., it may 

 well be considered as one of the finest specimens of engineering that has ever 

 been produced. As an example of an excellent mechanical structure carry- 

 ing a large object-glass, I think it probable that this Greenwich transit-circle 

 may have a great influence on the construction of future instruments. I had 

 hoped to be able by this time to report to the Association on the American 

 method of recording transits, by a puncture or dot produced by a galvanic 

 agency whose circuit is closed by a touch of the observer's finger, — and espe- 

 cially on its fitness for the wants of a really active observatory ; but the de- 

 lays of construction have prevented me from doing so. Shortly before the 

 last meeting of the Association, the President for the time (Dr. Robinson) 

 transmitted to the Government, on the part of the Association, a general 

 request that a large reflecting telescope might be sent to some of the British 

 possessions in the southern hemisphere, for the purpose of observing the 

 southern nebulse ; and shortly after that meeting an answer was received 

 from the Lords of the Treasury, to the effect that their Lordships entirely 

 recognised the importance of the object, but that there appeared to be prac- 



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