cles the
contact of the outside half of the pen will have less contact with the
paper. The smaller the circle, the more difficult it is to keep the
point-leg from slipping out of the centre, and the more difficult it is
to draw a clear line and true circle; hence the points should be shaped
to the best advantage for drawing these small circles, by oil-stoning
the pen, as already described, and then finishing it as follows:

After the oil-stoning, open the two valves of the pen-leg wide enough to
admit a piece of 000 French emery paper wrapped once around a very thin
blade, and move the pen endwise as described for the straight-line pen.
This will smooth the inner surfaces and remove any fine wire-edge that
the oil-stone may leave. Close the two halves of the pen again, and
lightly emery-paper the outside faces, which will leave the edge sharp
enough to cut the paper. The removal of the sharp edge still left, to
the exact degree, requires great care. It may best be done by closing
the pen until its two halves very nearly, but not quite, touch, then
adjust it to mark a circle of about 3/16 inch diameter, and strike a
number of circles in different locations upon the surface of a piece of
0000 French emery paper.

In marking these circles, however, let the instrument stand out of the
perpendicular, and do very little while standing vertically. Indeed, it
is well to strike a number of half-circles, first from right to left and
then from left to right, and finally draw a full circle, sloping the pen
on one side, gradually raising it vertically, and finally sloping it to
the other side. This will insure that the pen has contact at its extreme
point, and leave that point fine and keen, but not enough so to cut the
paper. To test the pen, draw small circles with the pen rotated first in
one direction and then in the other, closing its points so as to mark a
fine line, which, if the pen is properly shaped, will be clear and fine,
while if improperly formed the circle drawn with the pen rotated in one
direction will not coincide with that drawn while rotating it in the
other. The same circle may be drawn over several times to make a
thorough test. If a drawing instrument will draw a fine line correctly,
it will be found to answer for thick lines which are more easily made.

In thus preparing the instruments, the operator will find that if he
occasionally holds the points in the right position with regard to the
light, he will b