denominated the Aerial Reflector. 51 



and most respectable writers on this subject, in the Edinburgh 

 Encyclopaedia, art. Optics, and in the last edition of his Appendix 

 to " Ferguson''s Lectures," has the following remarks : — " If we 

 could dispense with the use of the small specula in telescopes of 

 moderate length, by inclining the great speculum, and using an 

 obhque, and consequently a distorted reflector, as proposed first 

 by La Maire, we should consider the Newtonian telescope as 

 perfect ; and, on a large scale, or when the instrument exceeds 

 20 feet, it has undoubtedly this character, as nothing can be 

 more simple than to magnify, by a single eye-glass, the image 

 formed by a single speculum. As the front view is quite im- 

 practicable, and indeed has never been attempted in instruments 

 of a small size, it becomes of great practical consequence to re- 

 move, as much as possible, the evils which arise from the use of 

 a small speculum," &c. 



The instruments now described have effectuated the desirable 

 object alluded to by this distinguished philosopher ; and the mode 

 of construction is neither that of Dr HerschePs front view, nor 

 does it coincide with that proposed by La Maire, which appears 

 to have been a mere hint that was never reahzed in the construc- 

 tion of reflecting telescopes of a small size. The simplicity of 

 the construction of these instruments, and the excellence of their 

 performance, have been much admired by several scientific gen- 

 tlemen, and others to whom they have been exhibited ; and so 

 much am I convinced of their utiHty, that I have dismantled 

 every other Gregorian telescope I had in my possession, and 

 fitted it up in the form now described ; and I seldom use any 

 other telescope either in terrestrial or celestial observations. As 

 it is distinguished from every other telescope, in being used 

 without a tube, I have chosen to denominate it " The Aerial 

 Reflector "^r 



Perth, April 1826. 



• A caveat has been lodged at the patent office, in the view of taking out 

 ^ patent for this construction of the reflecting telescope. A brief notice of it 

 was published, about three years since, in the Appendix to a work entitled, 

 " The Christian Philosopher.' 



2 D 2 



