The instrument shown in the cut is the invention of Mr. Maginnis, and is
designed for producing equidistant hatchings. It consists of a short
ruler, A, and a triangle, B, supposed to be one of 45°, but which may be
of any angle. The triangle carries two stops, c c, while the ruler is
provided with a conical piece, D, which is slotted, and is held by a
screw. The play that occurs between this conical slide and the stops
varies according to the position of the former.
[Illustration: RULER AND TRIANGLE FOR HATCHING.]
The apparatus operates as follows: In the figure, the stop to the right
being in contact with the piece, D, a line is drawn along the right side
of the triangle. Then the ruler is made to slide along the triangle until
D touches the other stop, and then the triangle is slid along the ruler
until the stop to the right touches D again. In this position another
line is drawn, and so on. The position of the piece, D, between the stops
is regulated according to the fineness of the hatching to be
done.--_Chronique Industrielle_.
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