denominated the Aerial Reflector. 45 



lescope, would, perhaps, find it difficult, in the first instance, to 

 make this adjustment; but, were it at any time deranged, 

 through accident or otherwise, I can easily make the adjustment 

 a-new, in the course of five or six minutes. 



In pointing this telescope to the object intended to be viewed, the 

 eye is applied at K (fig. 1.), and looking along the arm, towards 

 the eye-piece, till it nearly coincide with the object, it will, in 

 most cases, be readily found. In this way I can easily point this 

 instrument to Jupiter or Saturn, or to any of the other planets 

 visible to the naked eye, even when a power of 170 or 180 times 

 is applied. When high magnifying powers, however, are used, 

 it is expedient to fix, on the upper part of the short tube in 

 which the speculum rests, a finder, such as that which is used in 

 Nevvtonian telescopes. When the moon is the object intended 

 to be viewed, she may be instantly found by moving the instru- 

 ment till her reflected image be seen from the eye-end of the te- 

 lescope on the face of the mirror. 



I have fitted up five or six instruments of the above descrip- 

 tion, with specula of 8, 16, 27, 35, and 49 inches focal distance. 

 One of these having a speculum eight inches focus, and two in- 

 ches diameter, with a terrestrial eye-piece, magnifying about 24 

 times, forms an excellent parlour telescope, for viewing land ob- 

 jects, and exhibits them in a brilliant and novel aspect. When 

 compared with a small Gregorian, of the same size and magnify- 

 ing power, the quantity of light upon the object appears nearly 

 doubled, and the image is equally distinct. It represents ob- 

 jects in their natural colours, without that dingy and yellowish 

 tinge which appears when looking through a Gregorian. Ano- 

 ther of these instruments, having a speculum of 27 inches focal 

 distance, and an astronomical eye-piece, producing a magnifying 

 power of about 100 times, serves as an excellent astronomical te- 

 lescope. By this instrument the belts and satellites of Jupiter, 

 the ring of Saturn, and the mountains and cavities of the Moon, 

 may be contemplated with great ease and distinctness. With a 

 magnifying power of 40 times, terrestrial objects appear extreme- 

 ly bright and well defined. Another of these instruments is a- 

 bout 4 feet long. The speculum which belongs to it is a very 

 old one : when it came into my possession, it was so completely 

 tarnished, as scarcely to reflect a ray of light. After it was clean- 



