When the graver or drill is too hard, which may be known by the frequent breaking of the point, temper as follows: Heat a poker red hot, and hold the graver to it within an inch of the point, waving it to and fro till the steel changes to a light straw color; then put the point into oil to cool, or hold the graver close to the flame of a candle till it be of the same color, and cool in tallow; but be careful either way not to hold it too long, for then it will he too soft, in which case the point will be blue, and most be broken off, and whetted and tempered anew. For jewellers' drills, no better tempering liquid can he got than the first-named liquid under the blacksmiths' department, which see.