g$ Microscopical Essays. 



the object ; regulate the focus of the magnifier by the fcrew CX 

 The moft pleafing magnifiers in ufe are the fourth and fifth. 



The fize of the object may be increafed or diminifhed, by 

 altering the diftance of the fcreen from the mierofcope : five or fix 

 feet is a convenient diftance. 



To EXAMINE TRANSPARENT OBJECTS OF A LARGER SIZE, 



or to render the inftrument what is ufuaily called a megalafcope, 

 take out the Aider, Fig. 3, from it's place at n, and fcrew the but- 

 ton, Fig. 4, into the hole at P, Fig. 2, and remove the glafs 

 which is under the plate at m, and regulate the light and focus 

 agreeable to the foregoing directions. 



N. B. At the end of the tube G there is a. lens for increafing 

 the denfity of the rays, for the purpofe of burning or melting any 

 combuftible or fufible fubftance ; this lens muft be removed iris 

 moft cafes, left the objects fhould be burnt. The intenfity of the 

 light is alfo varied by moving this tube backwards or forwards. 



Apparatus of the opake Solar Microscope*, 



The large fquare plate and mirror. 



The body of the mierofcope. 



The opake box and it's tube. 



The tooth and pinion mierofcope. 



The 



