Microscopical Essays, 105 



N is a pair of forceps, or pliers, for the taking up of infects or 

 other objects, and adjufting them in the glades. 



O, a little hair brum or pencil, wherewith to take up and 

 examine a fmall drop of liquid. 



P is a tube of glafs to confine living objecls, fuch as frogs, 

 fifties, &c. in order to difcover the circulation of the blood. 



When you would view an object, thruft the ivory Aider, in 

 which the faid object: is placed, between the two flat brafs plates, 

 obferving always to put that fide of the Aider where the brafs 

 rings are Far theft from the eye ; then fcrew in the magnifying 

 glafs you intend to ufe at the end of the inftrument G, and look- 

 ing through it againft the light, turn the long fcrew C C till your 

 object is brought to the true focal diftance, which you will know 

 by it's appearing perfectly clear and diftin6L 



The way of examining any object accurately, is to look at it, 

 firft, through a magnifier that will ftiew the whole at once, 

 and afterwards to infpect the feveral parts more particularly with 

 one of the greateft magnifiers ; for thus you will gain a true idea 

 of the whole, and all it's parts : and though the greateft magni- 

 fiers can mew but a minute portion of any object at once, fuch 

 as the claw of a flea, the horn of a loufe, or the like, yet by 

 gently moving the Aider that contains your object, the eye will 

 gradually fee the whole ; and if any part mould be out of the 

 focal diftance, the fcrew C C will eafily bring it to the true focus. 



As 



O 



