282 Superiority of Tit Blair's Achromatic Telescopes 



are always formed. It also affords a most suitable material 

 for the toorbut erected over the body under the centre of the 

 dome of these magnificent structures, and which is generally 

 covered with inscriptions from the Koran. 



I had requested my friend to send me a specimen of the 

 polished granite, which he has only been prevented from doing 

 by want of a suitable opportunity. 



Edinburgh, \5th February 1826. 



Art. XIX. — Observations on the Superiority of Achromatic 

 Telescopes with Fluid Object-Glasses^ as Constructed by Dr 

 Blair. 



Although it cannot be doubted that the Achromatic Tele- 

 scope, from its first invention to its latest modifications, is a 

 British invention, to which no foreigner has made the slight- 

 est addition, yet no attempt of any magnitude, and with any 

 reasonable prospect of success, has been made in Great Bri- 

 tain for perfecting this noble instrument. Contented with 

 supplying the European market with this article of their 

 manufacture, our opticians have blindly followed the ancient 

 routine ; and neither our government, nor our public institu- 

 tions, have originated or encouraged any attempt at improve- 

 ment. The opticians of France and of Germany, on the con- 

 trary, have been busily employed, not only in rivalling the 

 English in their methods of working lenses, but, with the aid of 

 public bodies, and of the government itself, they have devot- 

 ed themselves to the more important object of perfecting the 

 glass of which the lenses are composed. The success which 

 they have obtained in these respects has exceeded even their 

 own expectations ; and the telescopes of M. Fraunhofer of 

 Munich, and of M. Lerebours of Paris, * have been brought 

 to such perfection, as to threaten England with the loss of one 

 of the staple articles of her manufacture. 



* The opinions of Mr Herschel and Mr South on these telescopes will 

 be given in a subsequent article. See page 309. 



