114 CLASSIFICATION OF 
they have a mouth with palpi, a spiral tongue, and a 
body set with hairs. The scales resemble feathers ; 
they lie over one another, in an imbricated manner, 
are formed of it, of amazingly fine workmanship; imitations 
of buildings, trees, ground of various kinds, and distant moun- 
tains; and the human figure, both singly and in groups. These 
are produced by small pins, of variously coloured glass, stuck 
into a kind of paste. They are so minute in many cases, that we 
can hardly discern them to be an arrangement of an infinite 
number of particles of glass; they rather look like a picture 
painted with the finest colours, harmoniously blended together. 
The calculation made by Keysler is, that a piece of eighty 
square feet, if perforated with tolerable care and delicacy, would 
employ cight artists the space of two years. 
A small piece of the wing of Papilio Io, (the Peacock 
Butterfly, ) a quarter of an inch square, was cut out and placed 
under the third magnifier of an opaque microscope, when 
seventy rows of scales were counted, and ninety in each row. 
Consequently, there were six thousand three hundred scales 
on one side of this small portion of wing; so that the square 
inch of a wing must contain the astonishing number of one 
hundved thousand seven hundred and thirty-six scales. The 
number of glass pins in a square inch of mosaic being only 
eight hundred and seventy, the coarseness of such a picture, 
compared with the mosaic of the wing of this insect, is in the 
proportion of one hundred and fifteen at least to one; that is, 
such a picture is one hundred aud fifteen times coarser than 
this natural mosaic. 
The Peacock Butterfly is one of medium size, and the sealos 
on it are in proportion to its size. What then must be the 
proportion if we compare with it some of the smaller Butterflies, 
whose whole dimensions are not a quarter of an inch ? 
The wing of a Peacock Butterfly, prematurely taken out of 
