Ohservatidns on Ins^eis. 509 
like multiplying glasses, have innumerable surfaces, on every one of 
which the objects are distinctly formed. Other creatures are obliged 
to turn their eyes ; but insects have always some one or other of these 
lenses directed towards objects, from what quarter soever they may 
present themselves. Mr. Nook computed that there were 14,000 of 
these lenses in the two eyes of a drone; and Mr. Leuwenhoek 
reckons 12,544 lenses in each eye of the Dragon Fly. The pictures 
of objects that are delineated on these, must be millions of times less 
than those formed on the human eye. Many insects still smaller, 
have eyes so contrived as to discern objects some thousands of times 
less than themselves ; for such the minute particles on which they 
feed, must certainly be. 
With respect to the wings of insects, those of the two first orders of 
Linnaeus have their wings defended by a pair of hard crustaceous 
cases, called elytra. The three subsequent orders have four mem- 
branaceous wings without elytra. All the insects of the sixth order 
have but two wings, and under each of these, at its base, there is a 
poise, or balancer. These poises are commonly little balls, each placed 
on the top of a slender stalk, and moveable every way at pleasure. 
The use of the poises to an insect seems to be precisely the same as 
that of a long pole, loaded at each end with lead, is to a rope dancer; 
— they render the body steady, and obviate all its unsteadiness in 
flight. 
The structure of the feet of these diminutive creatures is truly ad- 
mirable. Those insects that live altogether in water, have their feet 
long, flat, and somewhat hairy at the edges, well adapted to aid their 
motions in that element. Such as have occasion to burrow into the 
earth, have their legs broad, sharp-edged, and serrated. Those 
that use their feet only in walking, have them long and cylindrical. 
Some have their feet furnished with sharp hooked claws, and skinny 
palms, by which from the pressure of the atmosphere upon them, they 
are enabled to walk on glass and other smooth surfaces, even with 
the back downwards. 
The tongue of insects is a taper and compact instrument, by which 
they suck their food. Some of them can contract or expand it ; others, 
as the Butterflies, roll it up under their head, somewhat like the spring 
of a watch. In many, it is enclosed within a sheath; and in several, 
as the Flies, it is fleshy and tubular. 
The mouth is generally placed somewhat underneath the front part 
of the head ; but in a few of the tribes it is situated below the breast. 
Some insects have it furnished with a kind of forceps, for the purpose 
of seizing and cutting their prey; and in others it is pointed, to pierce 
animal or vegetable substances, and suck their juices. In several it 
