$6 Mechanical Pliiiosophy. 



most wonderful magnifying power. The extraor- 

 dinary length to which he has carried his im- 

 provements, and the astonishing discoveries which 

 they have enabled him to make, are too recent, 

 and too well known to make a detail of them ne- 

 cessary here. 



During the period which we are considering, 

 viicroscopes have been also carried to very high 

 degrees of perfection. In 1702 Mr. Wilson in- 

 vented one, of the single kind, which is still much 

 in use. In 1710 Mr. Adams presented to the 

 Royal Society, another, also single, but of much 

 greater magnifying power. To which succeeded^ 

 soon afterwards, the ingenious device of Mr. Grey, 

 of a temporary microscope, by means of a globule 

 of water. In 1738 or 1739, Mr. Lieberkuhn 

 made two very important improvements in micro- 

 scopes, by the invention of the Solar Microscope^ 

 and that for viewing opaque objects. These were 

 followed by the rejlcct'mg microscope of Dr. Smith^ 

 said to be superior to all others. Besides those 

 above mentioned, discoveries and improvements 

 relative to microscopes, too numerous to be re- 

 counted, have been made by philosophers and 

 practical opticians. The most conspicuous of theses 

 are Culpeper, Baker, Ellis, Lyonet, Martin^ 

 Cuff, Adams, and Withering; who have either 

 contrived microscopes suitable for particular pur-* 

 poses, or suggested inventions and additions of 

 more general application. 



There is probably no division of this review,- 

 under which another modern invention, the Tele- 

 '^raphi may with more propriety be placed than 

 this. Though something like Telegraphic com- 

 munications had been attempted many centuries 

 before, on particular military or civil emergences; 

 yet nothing of this kind was reduced to regular 



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