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THREE:As to the shades that appear in drawing temper, or tempering it is sometimes called, it is quite useless to repeat any of the old rules about "straw colour, violet, orange, blue," and so on; the learner knows as much after such instruction as before. The shades of temper must be seen to be learned, and as no one is likely to have use for such knowledge before having opportunities to see tempering performed, the following plan is suggested for learning the different shades. Procure eight pieces of cast steel about two inches long by one inch wide and three-eighths of an inch thick, heat them to a high red heat and drop them into a salt bath; preserve one without tempering to show the white shade of extreme hardness, and polish one side of each of the remaining seven pieces; then give them to an experienced workman to be drawn to seven varying shades of temper ranging from the white piece to the dark blue colour of soft steel. On the backs of these pieces labels can be pasted describing the technical names of the shades and the general uses to which tools of corresponding hardness are adapted.Second.��The steam establishes the greatest possible elasticity in the connection between a hammer and the driving power, and at the same time serves to cushion the blows at both the top and bottom of the stroke, or on the top only, as occasion may require.

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