ABSTRACT
This experiment uses two machines of quite different configurations. One consists of a piece of wood with a little man drawn on it that has slots opening into holes at both ends (Fig. 12.1) One starts by sliding the upper rung of a ladder through the slot and into the hole on the bottom, so that the man is sitting on the upper rung. The slots and holes are arranged in such a way that when the man is pushed off balance, he rotates to an upside-down position on the next lower rung. By repeating this procedure, one can produce a succession of rotatory movements around the rungs that bring the man to the bottom of the ladder. The second machine is composed of a toothed wheel whose movement is powered by a rubber band fixed to its axle and regulated by means of a cog-arm (Fig. 12.2). The cog-arm’s axle is provided with a pendulum. As the cog-arm seesaws, one end catches on a tooth on the wheel and thus blocks its rotation while the other end releases the tooth previously blocked. As is evident, the primary causal mechanism is quite different in the two cases. In the first, the man’s weight brings about his descent; in the second, a rubber band makes the wheel turn. By contrast, a regulating apparatus intervenes in both situations with the same effect, that is, to produce constancy of the overall speed, and does so by analogous means, the two ends of the man or of the cog-arm acting turn by turn to produce momentary braking of the moving part on one end just as it is let go on the other. Man on ladder apparatus. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780203771600/cdd8d45c-f71f-401b-b13f-75887a16c5b9/content/fig12_1_C.jpg" xmlns:xlink="https://www.w3.org/1999/xlink"/> Toothed wheel apparatus. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780203771600/cdd8d45c-f71f-401b-b13f-75887a16c5b9/content/fig12_2_C.jpg" xmlns:xlink="https://www.w3.org/1999/xlink"/>
