278 G. O. Sars— Practical use of Autography. 
less smooth surface, the paper will assume any degree of 
smoothness required, according to the character of the drawing. 
The next process is to fasten the paper to a sketching board or 
a piece of pasteboard; the drawing is then made by means of 
the lithographic crayon. I use a kind of crayon containing 
copal (‘“erayons copal’) and therefore less brittle than the 
common kind; and as this kind is also in other respects 
preferable, it had better always be used for this purpose. It 
can be obtained in small boxes from Monsieur Lemercier, Rue 
de Seine, St. Gn., 57, Paris. 
The paper must be cut to the size intended for a full plate, 
and the drawings arranged in the same order as they wil 
have to appear in the printed plate. The execution is exceed- 
ingly simple, and any draughtsman will easily acquire the 
ill in the work. The method is the same as in 
common drawing with lead pencil, or rather crayon. The 
_ figures should, however, first be sketched in outline on com- 
mon paper and then transferred to the prepared paper in the 
usual manner, by means of transparent paper and plumbago 
paper, blue paper, or, still better, red paper, the transferring 
being done with a lead pencil that is not too soft. The details 
of the figures, the shading and finer structural conditions may 
be drawn off-hand with the crayon on the prepared paper, 
after the outline has been transferred. Any correction or 
change in the drawing can easily be done by erasing with a 
fine scalpel, taking care only that the starch film be not 
injured. I have in this way made numerous corrections in my 
drawings without the slightest injury to the prints. When the 
plate is finished to satisfaction, it is transferred to a common 
smooth lithographic stone, in the following simple way. The 
back of the paper is moistened with water containing a small 
— of nitric acid; and, after having been put for some time 
etween moistened soft printing paper, the plate is laid, face 
downward, on the stone, which then for a moment is put in 
the press. To make more sure of it the outside of the paper 
weak etching, and will then be ready for printing. The whole 
process of transferring the drawing from the paper to the stone . 
is simple, but requires practice and great care. This should 
therefore be left to the charge of a professional lithographer. 
It may be thought that the zoologist, by taking on himself 
the execution of his plates, would have his labor excessively 
in is, however, is not really so. e drawing must 
at all events be made by the zoologist in one way or another 
