328 
DIRECTIONS I'OE THE MICROSCOPE. 
object in its own nature opaque, and renders it very difficult to be seen, 
unless by the help of a silver speculum. 
The nature of the object also, whether it be alive or dead, a solid 
or a fluid, an animal, a vegetable, or a mineral substance, must like- 
wise be considered, and all the circumstances of it attended to, that 
w'c 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 thin, 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 boles cut a little, 
larger 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 suffered 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- 
ner: Cut card- or drawing-paper into small pieces of about a quarter 
of an inch in diameter, and with a line 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, antemue, Ike. by means of a fine 
needle (as in pi. VI. fig. 0.); the gum, when dry, will fix the insect in 
tins position The seeds of plants, minerals, &c. may be preserved in 
this way. Taper of different colours should be chosen for different 
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 pt the pliers they may be examined in every direction ; 
a pin may be passed through the paper or card, and the objects 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 oh 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. 
