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.
The double-edged pruning saw with coarse teeth on one side and fine on the other would be far more widely used, if it were not for the fact that the unused edge so often injures the bark of the trunk when the saw is being used. A very satisfactory guard may be quickly made of a brass curtain rod by prying it apart slightly at the seam and cutting: a suitable lensrth to fit over the edge, as shown in the sketch. This will cling to the saw blade by its own tension. - Contributed by James H. Brundage, Katonah, N. Y.
Ill: The Teeth on the Unused Edge are Covered with a Piece of Brass Curtain Rod