DIRECTIONS FOR THE MICROSCOPE— HISTORY. 333 
Every Entomologist should keep an exact journal of the insects he 
collects; with an account, as far as possible, of the place, food, times of 
appearance, &c. and place to each insect a Aumber corresponding with 
that of his journal; he should also make a catalogue in which the 
names, generic and specific, are to be expressed, as also the synonyms, 
with reference to such authors as have described them. In his jour- 
nal he must also insert observations on their manners, ceconomy, &c. 
to illustrate as far as possible their natural history, for there is little 
doubt that many valuable discoveries are yet to be made by a proper 
attention to insects. 
DIRECTIONS FOR THE MICROSCOPE. 
Microscope — an optical instrument, by means of which very mi- 
nute objects are represented exceedingly large, and viewed very di- 
stinctly, according to the laws of refraction or reflection. 
Microscopes are properly distinguished into simple or single, and 
compound or double. 
Microscopes, single, arc those which consist of a single lens or a 
single spherule. 
Microscopes, compound, consist of two or more lenses duly com- 
bined. As optics have been improved, other varieties have been con- 
trived in the sorts of microscopes ; hence we have reflecting micro- 
scopes, wider microscopes, Sec. Each ot these two kinds has its pecu- 
liar advantage ; for a single glass shows the object nearer at hand and 
rather more'distinct; and a combination of glasses presents a larger 
field, or, in Other words, exhibits more of an object equally magnified 
at one view. As each of these has its advantages, each of them has 
its advocates, at least in practice. The celebrated Leeuwenhoek never 
used anv but single microscopes ; and, on the contrary, Dr. Hook made 
all his observations with double ones. 
History — When, and by whom, microscopes were first invented is 
not certainly known. Huygens tolls us that one Drebefl, a Dutch- 
man, had the first microscope in the year 1631, and that he was re- 
puted the first inventor of it; though F. Fontana, a Neapolitan, in 
1646, claims the invention to himself, hut dates it from the year 1618. 
As a telescope inverted is a microscope, the discovery might easily 
enough have arisen from thence. 
Nothing more is certain concerning microscopes, than that they were 
first used In Germany about the year 1681. According to Borellus, 
they were invented by Zachartas Jansen, in conjunction with his son, 
who presented the first microscope they had constructed to Prince 
Maurice, and Albert archduke of Austria. William Borell, who 
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