This section is from the book "The Boy Mechanic Vol. 2 1000 Things for Boys to Do", by Popular Mechanics Co.. Also available from Amazon: The Boy Mechanic, Vol2: 1000 Things for Boys to Do.
When making long cuts with a cold chisel, it is almost impossible to guide the chisel edge along a line made with a scriber or pencil and have a straight cut. I find that it is much easier To use a guide, as shown in the sketch. The guide is made of a piece of wood, about 1 ft. long and 1 1/2 in. wide. A slot is cut in the center, wide enough To receive the chisel edge snugly, and about 9 in. long. The guide is clamped
The Guide Makes It Easy to Follow along a Straight Line When Cutting with a Cold Chisel to the work, and the cold chisel slipped along in the slot as it is successively Hit with a hammer. - Contributed by G. H. Holter, Jasper, Minn.