Microscopical Essays. 



lit 



the pin Is to be moved up and down, in order to adjuft the lenfes 

 to their focal or proper diftance from the objeci. 



N. B. In the reprefentation of this microfcope, Plate VII. B. 

 Fig. i, the pin D is delineated as palling through a locket at 

 one fide of the pillar A ; whereas it is ufual at prefent to make it 

 pafs down a hole bored through the middle of the pillar. 



E, the bar which carries the magnifying lens ; it fits into the 

 focket X which is at the top of the pillar D. This arm may be 

 moved backwards and forwards in the focket X, and fide ways by 

 the pin D, fo that the magnifier, which is fcrewed into the ring 

 at the end E of this bar, may be eafily made to traverfe over any 

 part of the objeci: that lays on the flage or plate B. 



E F is a polifliecl filver fpeculum, with a magnifying lens, 

 placed at the center thereof, which is perforated for this purpofe. 

 The filver fpeculum fcrews into the arm E as at F. 



G, another fpeculum, with it's lens, which is of a different 

 magnifying power from the former. 



H, the femicircle which fupports the mirror I ; the pin R, 

 affixed to the femicircle II, pafles through the hole which is to- 

 wards the bottom of the pillar A. 



B, the flage, or the plane, on which the objects are to be 

 placed ; it fits into the fmall dove-tailed arm which is at the 

 upper end of the pillar D A- 



