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.
Chair legs often become loose when chairs are handled roughly, so that the glue is broken up. A small device made from a piece of pointed metal, A, which is securely fastened to the end of the chair leg by means of a screw, will hold the legs more firmly than wire or glue. When the leg is driven into the hole, the points are pushed into the wood B as the metal flattens.
Ill: The Metal on the End of the Leg Fastens It Solidly in Place