This page has been validated.
TIME OF VOLUNTARY CONTRACTIONS
79
the movements of the fork, and then Mr. Heath will place it in the lantern. Then you see the words, and you will observe that the letters show little curves, each of which represents about one-two-hundred-and-fortieth of a second. By counting the little curves in any letter you can measure the time I occupied in writing it.
Fig. 40.—Time of making voluntary movements in writing letters. Each little wave is the one-two-hundred-and-fortieth of a second. Examine with a magnifying glass. In the experiment the lines were white on a black ground.
But let us return to the question of whether ordinary voluntary contractions are twitches or tetanic spasms. Another strong bit of evidence in favour of the occurrence of what we call
