Nature's Teachings: Human Invention Anticipated by Nature

by J. G. Wood

An ingenious robbery was once committed by means of the Siamese Link. A man of good address struck up an acquaintance with a jeweller. One day he produced a Siamese Link, and challenged him to get his fingers out when once they were in. So the jeweller was told to put his hands behind his back, and push his little fingers as far in as he could.

This he did, when the treacherous friend made a clean sweep of all the rings, brooches, ear-rings, and such jewellery as was within his reach, while the unfortunate jeweller was vainly tugging at the Link. This only occupied a few seconds for a practised hand, and the thief quietly opened the door, shut it, and was lost in the passing crowd before the jeweller could recover from his surprise.

On the left of the same illustration is a view of the muscles of the human leg, which, as the reader will see, are curiously like the distended cassava press. Although the mode of applying the force differs, the principle is the same.

In the latter case an external force is applied to the press, but in the latter an internal, or rather a central, force is applied to the bones. It is evident that if a similar process were carried on with the cassava press, and the central portion forcibly distended, the supports at either end would be drawn powerfully towards each other. Substitute the muscle for the press, and the bones for the poles, and this is muscular action.

Here we have a diagram which speaks for itself, as far as muscular action is concerned, but there is another point to which we shall presently pass.

The muscle of the arm is seen running along the bone, passing over the elbow, where it is held down by a tendinous band, and, by its contraction, enabling the arm to be bent so as to uphold a considerable weight. The mechanical analogy between this arrangement and the common Steelyard is too evident to need any explanation except inspection of the diagram.

There is, however, another point which is worthy of consideration. The muscle does not proceed at once from the shoulder to the wrist, but passes under the tendinous band above mentioned, and so produces a change of direction when the arm is bent.

There is a more complicated arrangement of a similar character in the human hand, a diagram of which is given in the left-hand figure of the accompanying illustration.