Draw the temper from the spring, and fit it properly in its place in the watch; then take it out and temper it hard in rain-water (the addition of a little table-salt to the water will be an improvement:) after which place it in a small sheet-iron ladle or cup and barely cover it with linseed oil; then hold he ladle over a lighted lamp until the oil ignites; let it burn until the oil is nearly, not quite all, consumed; then re-cover with oil and burn down as before; and so a third time; at the end of which, plunge it again into water. Main and hair springs may, in like manner, be tempered by the same process: first draw the temper, and properly coil and clamp to keep in position, and then proceed the same as with case springs.