Fig. 270 shows the steps in the work of cutting the small helical gear wheel shown at W in Fig. 92, Chap. VI. This is done in six operations, requiring a total of 80 seconds of time. A dimension drawing of the wheel is shown at the bottom of the illustration. Operation IV, that of cutting the spiral teeth, is done by a very ingenious tool made up of several moving parts, all automatically operated, and designed at the works of The Brown & Sharpe Mfg. Co., Providence, R. I.