The Wheel.
Yet another aid to locomotion is found in the Wheel, a contrivance for diminishing friction.
When man first learnt that heavier weights could be dragged than carried, he simply placed them on flat boards to which ropes were attached. The next step was necessarily the invention of the sledge, the burden resting on two parallel runners, the ends of which were slightly curved so as to prevent them from hitching against any small obstruction. In some countries—such, for example, as in Esquimaux-land—the sledge is the only vehicle practicable, and even Europeans, when they visit that country, are fain to adopt the sledge if they would live.
But, in more temperate zones, the Wheel is paramount. In its earlier stages the wheel was a very simple business. It was simply a section of, a tree-trunk, dubbed roughly round, and with a hole in the centre, through which the axle passed. Such wheels are still in existence in many parts of Europe; and, owing to the want of regularity of outline in the circumference, and the utter absence of grease, the wheels keep up a continuous shriek, almost deafening to those who are unused to it, but perfectly unheeded by those who own or drive the vehicle.
The next improvement was to make the circumference of the wheel as perfectly circular as the art of man could devise, and, instead of having the wheel solid, to fill up its interior with spokes, thus gaining lightness and strength at the same time.
Of all locomotive wheels, I suppose that the modern Bicycle affords the best example. The driving wheel is larger than the hind wheel of an ordinary coach, and yet the spokes are not nearly so thick as the porcupine quill with which this account is written.
If we look at the ancient sculptures and paintings of Egypt and Assyria, as preserved in the British Museum, we shall see that either kind of wheel was used according to the work which it had to do. The solid, uneven, squeaking, wooden wheel was devoted to agriculture, while the light, spoked wheel was sacred either to warfare or hunting.
Let us hope that in the two latter cases some modicum of grease might have been used, as the outcries of tortured and unlubricated machinery are enough to drive away all wild beasts which come within the range of its complaints, while the nervous system of hunter or warrior must have been seriously damaged by it.
Even in such a structure as the spoked Wheel, Nature has anticipated Man.
My readers may remember that, when treating of nautical matters, I mentioned the singular anchor-shaped spicules that are found upon one of the sea-slugs, called Synapta.
There is another group of these creatures inhabiting the Mediterranean, in which the skin-spicules take a different form. Like those of the Synapta, they are too small and translucent to be seen without the aid of the microscope and carefully adjusted light. But, just as the spicules of the Synapta resemble the ancient anchor, so do those of the Chirodota resemble the ancient wheel, the similitude being in both cases absolutely startling.
Not only that, but, as all readers must be aware, if they have studied practical mechanics, there are many machines which are toothed on the inner, and not the outer, side of the circumference. Here, in the Chirodota, the inner toothing is manifest.
What purpose it serves we know not. The Chirodota’s wheels (of which there are thousands) never revolve, neither do the anchors of the Synapta hold the ground. Yet the very fact that such exceedingly minute objects should be so carefully constructed tells us at once that they must have some important purpose to serve, though at present that purpose is a mystery which no one has attempted to solve.
I have little doubt that when the hour and the man arrive, as arrive they surely will, we shall find in these tiny and almost unrecognised spicules the keys to treasures of wisdom which at present have been opened to no human being.
The whole history of the progress of the human race shows that facts have been allowed to accumulate, fought about, and turned in all directions, before the generaliser comes who pierces to the heart of everything, reduces apparent discrepancies to harmony, and usually is rewarded by finding some one else assume the credit of his discoveries, and receive all the honours and emoluments.
USEFUL ARTS.
CHAPTER XIV.
Paper and its many Uses.—The Egyptian Papyrus.—India Paper.—China and its Manufactories.—Materials of which Paper is made.—Annual Consumption of Material.—The “Water Mark.”—Nature’s Papers.—Wasps and Hornets.—The common Wasp, and the various Materials of its Nest.—Utilisation of Material.—Papier-mâché.—Printing.—Nature-printing.—Method and Results of the Process.—Use of the Electrotype.—“Facing” the Copper Plates with hard Metal.—The Coal Mine and its Nature-printing.—Stippling, its Use and Abuse.—The Line and the Dot.—Modification of the Dot.—Flower-petals.—The Pelargonium.—Plaster Castings.—Stereotyping and Electrotyping.—Modern Method of taking Plaster Casts.—The Principle of Corrugation.—Flower-pot Covers.—Iron Buildings.—The Polistes and its Corrugated Dwellings.