OBSERVING WITH AND MANAGING ENGISCOPE. 203 



security against burning 1 it, or injuring the object- 

 glass itself. The object, if below a certain size, will 

 of course be seen upon a ground of some sort, and this 

 must be a black one : if on a slider, it must be gummed 

 upon black paper ; or, if mounted upon a cork cylinder, 

 having a pin thrust through it, the surface of the cylinder 

 must be blacked with lampblack and glue, before the 

 object is applied to it : but if it is of a nature to be held 

 by the nippers, Mr. Lister's black ground (fig. 22) must 

 be employed to bring it out in true relief; for it is far 

 blacker than any other, and stifles all heterogeneous 

 light much more perfectly. This is attached to the 

 stage in the same way as the live-box or slider-holder ; 

 and is, in fact, the same piece of apparatus which con- 

 stitutes the false stage for the simple microscopes, and 

 for dissecting 5 with the top and bottom, 'n, 'p, applied 

 hi their proper places, to close it up. In the present 

 case, its dark abyss is to form the ground against which 

 the object is examined. At the other end of the needle 

 is a piece of cork, contained in a bit of brass tube. This 

 is to receive the pin by which insects are retained in 

 their drawers in entomological cabinets, which can thus 

 be taken out and examined without injury ; more espe- 

 cially if the pins have been thrust through them diago- 

 nally, which is a great convenience when applied to the 

 microscopes, as it allows their backs and bellies to be 

 freely presented to the action of the object-glass. The 

 nippers, seen of their natural size at fig. 23, are drilled 

 through at s, so as to lay hold of the head of a pin, and 



