1825 .J on the Planet Venus, ^ 411, 



a Urs^e Minoris, I Ursse Maj oris, the quadruple star e Lyrae, 

 Rigel ; together with the whole of those in Dr. Herschel's first 

 class, which can be seen with the powers I can command. In 

 the spring of the present yeai', I have shown the double ring and 

 quintuple belt of Saturn, and once a spot upon his southern 

 hemisphere, to several persons ; it shows the most minute parts 

 of the solar spots, as well as the mottled appearance of his sur- 

 face, as perfectly as any instrument I have ever seen ; and the 

 spring of the present year afforded many opportunities of trying 

 its powers in this respect ; for example, March 3, within one 

 umbra of small size were 11 nuclei, all distinctly defined. 



The refractors consist of one convex object lens and a convex 

 eye glass. I have often compared them with the reflector, and 

 Myiih other instruments, and in point of steadiness there is no 

 comparison ; on account of their great length, causes which 

 produce great tremor in shorter instruments do not aii'ectthem; 

 also, what is very curious is, that when the air is in such a state 

 as to produce great undulations, when the reflector is used, it 

 affects the others very little ; so that with them I can observe 

 objects when nearer the horizon than with other instruments. 

 With the aerial of 18 feet, I see Saturn's ring beautifully distinct 

 with a power of 36 ; with 70 some belts, and certainly a trace 

 of the division of the ring ; all seen with 50 foot, and power 160, 

 I have not had opportunity to make many observations on 

 double stars with these instruments ; the stars are well defined 

 through them : I have seen the double star Castor, and the 

 trapezium in the nebula of Orion's sword, and many much 

 closer ones. I have often compared these instruments with the 

 reflector, in viewing the moon and the solar spots ; every part 

 of the moon, even the most intricate, is seen in high perfection ; 

 the limb beautifully defined ; so also are the solar spots : indeed, 

 except I am taking any micrometric measures, I almost always 

 use the short aerial for viewing both the sun and moon. With 

 it, the mottled appearance of the sun is very conspicuous, and 

 the solar spots are blacker than with any reflector I have ever 

 seen. The bright ridges of the sun are seen in the highest per- 

 fection by receiving the focal image of a lens of very long focus 

 upon a white screen ; the sun's image in the focus of the object 

 lens of my long aerial is about 4i inches in diameter : in this 

 the ridges are seen in great perfection, together with the spots, 

 which are absolutely free from colour. It is to be regretted that 

 the simple astronomical refracting telescope has gone into 

 disuse : if the proper dimensions be observed, it is as free from 

 colour as any achromatic ; it is remarkably free from tremors ; 

 the number of surfaces are small ; and on account of the long 

 focal lengths used, small imperfections in the lenses, or defects 

 in the centerings produce but little effect. On these accounts 

 it possesses many advantages. In light it exceeds not only % 



