Some new apparatus. 99 with the covered opening. He finds before him a rubber button like that on a telegraph key. He is to press this button as soon as be sees the shutter move. He does so, and apother mechanism releases a horizontal bar running behind the scale. The pointer swings between this bar and the scale and is consequently stopped when the bar snaps against the scale. The pointer starts to move Fig. 15. when the shutter starts to fall and consequently any time that elapses thereafter will be indicated by the distance through which the pointer travels before being caught. The connection of the pointer with the pendulum is so light that it continues its swing (fig. 15) and is finally caught on the other side. The scale in front is graduated by actual comparison with tuning- fork records made by the finest graphic methods. Special electrical contacts are arranged so that the units of the scale indicate always