e together, as in Figure
24; this has the advantage that the point is not hidden from
observation.

In forming the pen-point the greatest refinement is necessary to enable
the drawing of very small true circles, say 1/16th of an inch, or less,
in diameter. The requirements are that the pen-point shall meet the
surface of the paper when the needle-point has entered it sufficiently
to give the necessary support, and that the instrument shall stand
vertical, as shown by the dotted line in Figure 24. Also, that the pen
shall then touch the paper at a point only, this point being the apex of
a fine curve; that this curve be equal on each side of the point of
contact with the paper; that both halves forming the pen be of equal
thickness and width at the pointed curve; and that the point be as sharp
as possible without cutting the paper.

The best method of attaining these ends is as follows: On each side of
the pen make, with an oil-stone, a flat place, as C D, Figure 27 (where
the pen-point is shown magnified), thus bringing both halves to an edge
of exactly equal length, and leaving the point flat at D. These flat
places must be parallel to one another and to the joint between the two
halves of the pen. As the oil-stone may leave a slightly ragged edge, it
is a good plan to take a piece of 00 French emery paper, lay it on a
flat surface, and holding the instrument vertically remove the fine edge
D until it will not cut. Then with the oil-stone shape the curved edge
as in Figure 28, taking care that the curve no more than brings the flat
place D up to a true curve and leaves the edge sharp, with only the very
point touching the paper, which is represented in the cut by the
horizontal line.

[Illustration: Figures 27. 28. 29. 30. 31. 32.]

The point must have a sharp edge all around the curve, and the two
halves must be exactly equal in width, for if one half is wider than the
other, as in Figure 29 at a, or as in Figure 30 at b, it will be
impossible to draw a very small circle true. So, likewise, the two
halves of the pen must be of exactly equal length, and not one half
longer than the other, as in Figures 31 or 32, which would tend to cut
the paper, and also render the drawing of true small circles
impracticable.

When the pen is closed to draw a very small circle the two halves of the
pen-leg should have an equal degree of contact with the surface of the
paper, and then as the legs are opened out to draw larger cir