

94 SECTION PHYSICS. 



the improvements which he has been making in the great telescopes 

 which he inherited from their constructor. It will be in the recol- 

 lection, I daresay, of many of you, that in all instruments at that time 

 you had to get two movements, and it is no easy task to mount them 

 on an axis inclined parallel with the earth's axis. That, Lord Rosse 

 has now effected, and is now improving the equatorial mounting, and 

 also the means for the observer to reach the telescope, which is not 

 very easy with either of those enormous instruments. He has nearly 

 completed the mounting of the three feet, and if that is farther carried 

 on to the six feet telescope, we may expect far greater results than it 

 has hitherto yielded, inasmuch as the objects which have to be 

 observed are, of course, carried round by the diurnal motion of the 

 earth, and the large telescope being mounted only with an hour's 

 range on each side of the meridian, you perhaps can only catch them 

 very occasionally. If, however, he mounts the six feet telescope to 

 reach any part of the heavens, undoubtedly new features will ccme 

 out. It is a very beautiful investigation he has carried out with 

 respect to the heat radiation of the moon. It was thought at one 

 t ime that no heat reflected from the moon reached us, but he has 

 shown in the most effectual manner, eliminating all radiation from the 

 atmosphere near the moon, that there is a positive amount of heat 

 reaching us from the moon. 



I ought not to omit calling your attention again to this beautiful 

 apparatus, the thermopile the application, as he has said, of an 

 ordinary thermopile. The difficulty of getting two exactly alike in 

 their indications is extremely great, but by this beautiful contrivance 

 of receiving the image of the moon on a large plate, and allowing it to 

 conduct the whole effect to one joint, was a very happy thought, and 

 it has been most admirably carried out. I beg you to offer your 

 thanks to Lord Rosse. 



Lord Rosse here took the chair, whilst Mr. De La Rue gave the 

 following account of his new battery: 



Mr. DE LA RUE : I have ventured to take somewhat out of order 

 'the description of a piece of apparatus which may have some interest 

 for you. It is a galvanic or voltaic battery, particularly applicable to 

 those cases where a very large number of elements is required. It 

 is extremely. -simple, and. consists essentially of a flattened wire of 



