THE STRENGTH OE NATURE'S MATERIALS.

Star (Christchurch), Issue 5769, 13 January 1897, Page 4

THE STRENGTH OE NATURE'S MATERIALS.

«, (Tit-Bits.) That Nature, when she produced living beings, intended them to be strongly made is evident from the fact that the materials Which she has chosen for their manufacture are, in comparison with their weight, far stronger than anything which we have up to now discovered which is not of animal origin. For the purposes of this article, however, we must take as living beings only such forms of life as have the power of locomotion — otherwise the line could not be drawn between the animal and the vegetable kingdom. Man himself is the highest form of locomotive life known, and so we will begin with him. Every student of anatomy knows that the human skeleton is so formed that the individual parts of it can bear tremendous strains, for the shape of the bones, their situations, &c, all con- . tribute to make the frame as economically strong as possible. But it is not everyone ■who has studied anatomy who knows the strength of living bone in proportion to other materials. ' An eminent scientific has calculated that if the skeleton of an adult were made of the finest and strongest steel instead of bone, it would, were it made strong enough to bear the same strain as tisa natural skeleton could bear, have to be between eight and nine times as heavy. Again, if a man holds the lower part of his arm at right angles to the upper, and places in his hand a weight of 561 b, the strain on that part where the end of the muscle joins the bone is. roughly, threequarters of a ton. Yet with this enormous strain upon it the muscle, except in certain diseases, which, of course, do not count, is never torn from its fastening on the bone, nor doe's the latter break, though were it made of ordinary iron it would snap like a piece of -wire, whilst the tendon would break like a thread. It is no hyperbole, therefore, to say that a man has muscles and sinews like steel — if the saying be absurd, it errs oii the scot*6 of the simile not being sufficiently forcible. All those persons who are in the habit of using a quill pen have probably noticed how remarkably rigid and yet how* light it is. We have, just meroly for curiositysake, weighed ours, and found its weight to be 23 grains — and it is a good long one. Yet that pen will keep rigid with a weight of 3Goz suspended from the thick end, when the shaft is held 3in up. A bar of steel — we say steel because it is the strongest dead matter known to man — would, to stand this strain, have to be about 3-32nds of an inch in diameter, and would weigh close upon half an ounce. Now, imagine a quill made of steel, and having the same wind-holding area, and the same strength as one made of the usual material. Its actual weight would be considerably over two ounces, and the bird who wore, such feathers would not be able to walk, much less fly, for his machinery would weigh several pounds. As we are on the subject of birds, it might not be out of place to mention a not widely-known fact about their eggs. The old trick of betting a "greenhorn" a sovereign to a shilling that he cannot break a hen's egg in his clasped hands, if one end be taken into the. hollow of each palm, is well known. The bet is always safe if the egg be fresh and uncracked, for then the strongest man could not crush it. To prove this there was an experiment tried in Paris a few years ago, the result of which showed that an egg has the power of resisting an enormous amount of equally distributed external pressure. A fresh egg was suspended by threads in an iron case, and the surface of the former was carefully measured, then water was v forced into the case until the indicator showed a pressure of 2501 b to the square inch, and, of course, the egg bore this pressure on every square inch of its surface. The pressure was increased until at last the case burst at an indicated pres- i sure of 3131 b, but the egg was unbroken. ' When a fresh and stronger case was px*ocured, the egg was finally broken at a pressure of '1631 b to the square inch. People who play the violin know the strength of catgut, which, by-the-bye, is not made of cat, but mutton. This is another example of the strength of animal tissue, and when it is taken into consideration that the strength of the raw or living ma- - terial is in the neighbourhood of twenty times that of the prepared gut, it will be 3 seen that this particular kind of string is one of the strongest things wo liave. For our last example we will go to tho spider, whose web is, as most people know, made of fine threads, each of which is composed of eight still finer ones twisted together. • Though the strength of this web may not seeu'i to be very great to the average . housemaid who sweeps it down with her broom or duster, it has been calculated that if theso threads, which are about l-8000th of an iuch in diameter, could be twisted into a rope a quarter of an inch thick, that rope would sustain a weight which would snap a Gin steel cable.