Microscopical Essays. 



As objects muff be brought very near the glades when the 

 greatefl magnifiers are ufed, be particularly careful not to fcratch 

 them, by rubbing the flider againft them as you move it in or 

 out. A few turns of the fcrew C C will eafily prevent this mif- 

 chicf, by giving it room enough. 



Description of a Scrole for fixing Wilson's Pocket 

 Microscope, and reflecting Light to it by a 

 Mirror. 



ABC, Fig. 2, is a brafs fcrole, which, for the better conve- 

 niency of carriage, is fo ordered as to take into three parts, and 

 put into the drawer upon which it Rands, with it's reflecting mir- 

 ror and Wilfon's pocket microfcope. 



The top part of the fcrole is taken off at B, by unfcrewing half 

 a turn of the fcrew ; then lift it up, and it comes out of the 

 focket. The lower part unfcrews at C, and the bafe unfcrews 

 at E. 



The mirror lifts out at F, which, with the fcrole, lie in one 

 partition of the box. 



To apply this fcrole to ufe, fix the body of the microfcope to 

 the top thereof by the fcrew A, as in Fig. 2, by fcrewing it in 

 the fame hole as the ivory handle. 



The brafs or ivory flider being fixed as before defcribed, and 

 the microfcope placed in a perpendicular pofition, move the re- 

 fleding glafs D in fuch a manner as to call the light of the iky, 

 i the 



