8 



him to the Armagh reflector,) appears to be very effective in 

 preserving the polish. 



In trying the performance of the telescope, Dr. R. had 

 the advantage of the assistance of one of the most celebrated 

 of British astronomers, Sir James South ; but they were un- 

 fortunate in respect to weather, as the air was unsteady in 

 almost every instance ; the moonlight was also powerful on 

 most of the nights when they were using it. After mid- 

 night, too, (when large reflectors act best,) the sky, in 

 general, became overcast. The time was from October 29th 

 to November 8th. 



Both specula, the divided and the solid, seem exactly 

 parabolic, there being no sensible difference in the focal 

 adjustment of the eyepiece with the whole aperture of 

 thirty-six inches, or one of twelve ; in the former case there 

 is more flutter, but apparently no difference in definition, 

 and the eyepiece comes to its place of adjustment very 

 sharply. 



The solid speculum showed a Lyrae round and well de- 

 fined, with powers up to 1000 inclusive, and at moments 

 even with 1600; but the air was not fit for so high a power 

 on any telescope. Rigel, two hours from the meridian, with 

 600, was round, the field quite dark, the companion separated 

 by more than a diameter of the star from its light, and so 

 brilliant that it would certainly be visible long before sunset. 



^ Orionis, well defined, with all the powers from 200 to 

 1000, with the latter a wide black separation between the 

 stars ; 32 Orionis and 31 Canis minoris were also well sepa- 

 rated. 



It is scarcely possible to preserve the necessary sobriety 

 of language, in speaking of the moon's appearance with this 

 ir.strjment, which discovers a multitude of new objects at 

 every point of its surface. Among these may be named a 

 mountainous tract near Ptolemy, every ridge of which is 



