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Rh runs into the electric beam, and is caught firmly by a spring that prevents it from rebounding. Mr. Heath had previously adjusted the electric lantern, and you now see on the screen the beautiful sinuous line, each wave of which represents the one-hundredth of a second.

You will be thinking that all this has not much to do with muscle, and I fear the description of these appliances may have been a little wearisome to you. But we must know something about the methods by which we attain results in science. This gives one a better appreciation, a better grasp, as I may say, of these results, and it shows us how men have got over difficulties in their attempts to explore phenomena. The recognition of how they have done this is an education by itself.

Now come to another physiological experiment. I have fitted up on this stand a number of pieces of apparatus, all intended for studying muscular contraction. First, at the top, you see a brass forceps which tightly holds the thigh bone of the frog's leg. You see again the gastrocnemius muscle hanging down, with its tendon, by means of a hook,