Directions for Triangular Guide Lines

Triangular guide lines are particularly adapted for the purpose of enlarging or reducing portraits.

In this exercise a small pencil sketch of the Father of His Country is offered as an example, showing the start of an enlarged drawing of the sketch.

The guide lines should be made as faintly as possible.

After the main outlines of the features and forms of the principal shadows are indicated with lines considerably stronger than the guide lines, the whole drawing may be rubbed over with dry bread crumbs. By this means the guide lines will be nearly; if not quite, obliterated, while the outlines of the features and shadows will remain sufficiently visible as a means by which to finish the drawing.

If the original is one that is to be preserved, and might be marred by the guide lines, one of these methods should be used:

(1) Tack a piece of very transparent tracing paper (the vegetable tracing paper is preferable for this purpose) over the original and place the guide lines on the tracing paper.

(2) Use tracing gelatine instead of paper and a steel point instead of a pencil, and with the latter scratch the guide lines on the gelatine. A coarse needle fastened into a cork as a handle makes a good tracing point.

(3) If the copy is very large pins may be placed at the points where the usual vertical, horizontal and oblique lines intersect the outer lines and thread carried from one point to the other instead of marked lines.