Microscopical Essays, 10 y 



the fun, or a candle, direct-ly upwards through the microfcope ; 

 by which means it is made to anfwer moll of the ends of a double 

 reflecling microfcope. 



It is alfo rendered more ufeful for viewing opake objccls by 

 fcrewing the arm O R, Fig. i , into the body of the microfcope at 

 G ; then fcrewing into the round hole R that magnifier which you 

 think will beil fuit your object, and putting the concave fpeculum 

 S, on to the outfide of the ring R, you will find in the body of the 

 microfcope, between the wood or brafs F, and the end of the 

 male fcrew' C C, a fmall hole u, through which Aides the long 

 wire T, which has a point at one end and forceps at the other, 

 that may be ufed occasionally, as your object, requires : when you 

 have fixed this, and your object, on it, turn the arm R, which is 

 performed by two motions, till the magnifier is brought over the 

 object ; it may be then adjufted to the true focus, by turning the 

 male fcrew C C in the fame manner as before defcribed. It mull 

 alfo be turned exactly over the fpeculum, by twilling the upper 

 part of the fcrole to one fide, till your objecl: and the two fpecu- 

 lums are in one line, as will be found by trial ; and then fix it by 

 the fcrew B, at which time the upper furface of the objecl; will be 

 lb exceedingly enlightened by the light reflected upward from 

 the mirror to the concave fpeculum, as to be feen as clear and 

 diftinct as any transparent one. 



Description of a small Microscope for opake Objects, 

 ,-Fig. 3 and 4, Plate II. B. 



A, Fig. 4, is a fixed arm, through which palfes a fcrew B, 

 the other end whereof is fattened to the moveable arm C. 



O 2 D is 



