The Microscope. 201 



leaving sufficient room between the glasses, the larger aquatic in- 

 sects may be viewed; such as small tadpoles, the ephemera, and 

 the water flea. When animalcules and other minute objects are 

 viewed with a lens of short focus, the following contrivance is 

 simple and useful: upon a suitable piece of glass describe a circle 

 with white paint; when dry, place the drop of water within the 

 circle, and cover it with a very thin piece of talc, the space be- 

 tween the talc and glass, produced by the paint, affords sufficient 

 room for the animalcules to move — the talc (if sufficiently thin) 

 offers no obstruction in bringing the object to the focus of the 

 lens. 



Slides for transparent and opaque objects. You will 

 find clear shps of glass preferable to talc in forming the shdes for 

 transparent objects; they may be prepared in the following man- 

 ner: take two slips of glass about the size of the ivory slides; then 

 get a piece of writing paper, with holes, of the same size; wet 

 one side of the paper with gum-water, and lay the glass upon it, 

 suffering it to dry; then place your objects in the holes, wet the 

 other side in the same manner, and lay on the other glass: any 

 curious objects may be preserved in this way without danger of 

 their perishing: talc may be appUed, as in the preceding article, 

 for deep powers. 



Opaque objects. Opaque objects maybe prepared for exam- 

 ination in the following way: cut a card or piece of stiff paper 

 the size of the object to be examined; put a Httle gum-water upon 

 it, and the insect will adhere to it, and may be viewed by placing 

 it under the microscope, on the stage; or by means of the steel 

 forceps it may be held in the hand as in fig. N. For viewing 

 minute opaque objects with a high power, with the body, a strong 

 light must be condensed and thrown down upon them by means 

 of a lens, but the single power or lens is better adapted for that 

 purpose. To preserve curious opaque objects, they may be 

 fixed on some slips of glass with gum-water, and another glass 

 placed over them, cemented together with sealing- wav . 



26 



