200 7%e Microscope. 



will shrink up. A delicate lancet, with a pair of the finest scis- 

 sors and forceps are generally used for such purposes. 



Mehtod of preparing and applying objects for the 

 Microscope. Most objects require a little management, in or- 

 der to bring them properly before the glasses : if they are flat and 

 transparent, put them between the talc in the slides, — the scales 

 of fishes for instance, ^c. In making your collection of objects, 

 if you wish to fill a number of slides, care should be taken to ar- 

 range them as near the size of each other as possible in the same 

 slider, in order that they may be examined by the same power. 

 Minute living objects, such as mites in cheese, small insects on 

 vegetables, <^c., should be delicately brushed off into the object- 

 box, and shut up; fllies, small beetles, ^c, may be held by the 

 forceps. 



To view the circulation of the blood, ^c. in aquatic insects, 

 place them in a small portion of water on a piece of flat glass; 

 two pieces of glass may be made open enough to receive any siz- 

 ed objects of this kind, similar to the animalcule apparatus. 



For viewing animalcules in fluids with the great- 

 est facility. The great difficulty of viewing animalcules in 

 fluids must have been felt by all who use microscopes. A drop 

 of water placed on a piece of glass forms a convex surface, and 

 when a high power is used, the animalcules are continually get- 

 ting out of the focus by diving to the bottom, and the drop very 

 soon dries up. 



The following contrivance effectually removes these obstacles, 

 when the focus of the power in use will admit one of the pieces 

 of glass to intervene between the surface of the lens and the ob- 

 ject. — It consists of two pieces of glass fixed with a small por- 

 tion of seahng-wax between them, and left open at the top. For 

 viewing animalcules, these pieces should be pressed as close to- 

 gether as possible, but for larger insects they may be left more 

 open. If a single drop of water is taken up by the small spoon 

 at the end of the forceps, and spread over the orifice, it will run 

 in between the two glasses, by which means the surface of the 

 water is rendered perfectly even, and the animalcules are distrib- 

 uted more truly, and confined in a more limited space, whereby 

 their forms and movements become more discernible. This 

 plan also prevents evaporation from the surface, which often dims 

 the lens, and perplexes the observer: a single drop of water may 

 be kept for ho»rs in this way, with any curious animalcule alive 

 in it. The glasses can be cleaned out by introducing a piece of 

 thin writing paper between them, and a drop of pure water. By 



