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.
To obtain the proper slope and apply a fine cutting edge, the plane iron or chisel must be held at the proper slope while grinding, and especially so when whetting. The illustration shows a holder to keep the iron or chisel at the proper slope. It con sists of a block of wood with a sloping cut at the right angle to make two pieces. One of these pieces is permanently fastened to the strip at the back, while the other is held with a bolt passing through a notch in the strip for adjusting or clamping. The rear end of the back piece is fitted with a large screw hook or L-hook to provide a slide to keep the rear end of the holder at the right height. The iron or chisel is inserted between the sloping edges of the blocks and clamped in place, then the L-screw is adjusted for height to secure the proper angle on the stone. It is then only necessary to move the block and tool back and forth over the stone.
The Tool Edge is Kept at the Proper Angle While It is Run over the Stone