328 DIRECTIONS rOR THE MICROSCOPE. 



object in its own nature opaque, and renders it very difficult to be seed, 

 unless by the help of a silver speculum. 



The nature of the object also, whether it be alive or dead, a solid 

 or a tiuid, an animal, a vegetable, or a mineral substance, must like» 

 wise be considered, and all the circumstances of it attended to, that 

 we may apply it in the most advantageous manner. If it be a living 

 object, care must be taken not to squeeze or injure it, that we may 

 see it in its natural state and full perfection. If it be a fluid, and that 

 too thick, it must be diluted with water ; and if too thui, we should 

 let some of its watery parts evaporate. Some substances are fittest 

 for observation when dry, others when moistened ; some when fresh, 

 and others after they have been kept some time. 



Transparent objects. — Most objects require also some management 

 in order to bring them properly before the glasses. If they are flat 

 and transparent, and such as will not be injured by pressure, the usual 

 way is to inclose them in sliders between talc, or, what is certainly 

 preferable, between two slips of glass. For this purpose thin and clear 

 glass must be used. The slips should be about three inches in length 

 and half an inch in width : a piece of paper, the size of the glass, 

 must be placed between them, with circular or oblong holes cut a little 

 laro-er than the object intended to be placed between them ; — one side 

 of the paper should be washed over with a little gum-water, fastened 

 on one of the glasses, and suftered to dry ; the objects are then to be 

 placed on the glass where the holes are cut in the paper ; the upper 

 part of the paper is then to be slightly touched with gum-water ; and 

 the other glass may be placed on it. This plan answers well for the 

 transparent wings of insects, &c. 



Opaque objects are best preserved and viewed in the following man-j 

 ner : Cut card- or drawing-paper into small pieces of about a quarter 

 of an inch in diameter, and with a fine camel's hair pencil, or the 

 point of a pen, put a little gum-water in the centre of it; if the ob- 

 -ect is an insect, display the legs, antenna', Sec. by means of a fine 

 needle (as m pi. 'i'i-Jig- 0.); the gum, when dry, will fix the insect in 

 this position. The seeds of plants, minerals, &c. may be preserved in 

 this way. Paper of ditferent colours should be chosen for difterent 

 objects, in order to render them the more conspicuous, such as a 

 black paper for a white subject, &c. 



Objects prepared in this way are extremely convenient for viewing, 

 and by means of the pliers they may be examined in every direction; 

 a pin may be passed through the paper or card, and the uljccts kept in 

 a small box lined with cork. The boxes may be made the size and 

 form of an octavo or quarto volume, and kept on shelves, in the man- 

 ner of books ; if made in the book form the backs should be lettered, 

 and the collection may be continued to any extent. 



