Image unavailable: SUBTERRANEAN ANTS’ NEST. SUBTERRANEAN HOUSE OF KAMSCHATKA.SUBTERRANEAN ANTS’ NEST. SUBTERRANEAN HOUSE OF KAMSCHATKA.
However much he might have rejected the ancient customs, it is evident that in this case, at least, he was punishing himself in rejecting these summer dwellings, which are always cool, and where, if one set of apartments is too warm, nothing is easier than to descend to the next.
Thisdwelling is made for the sake of coolness in summer. Another subterranean dwelling is made for warmth in winter, the non-conducting properties of the earth being in both cases brought into play. This is the winter dwelling of the inhabitants of Kamschatka.
During the summer-time the Kamschatdales live in comparativelyslight huts mounted on poles, and having the floor some ten feet from the ground.
During the winter, however, they live in habitations of a very different character.
In order to make these houses, they begin by digging a large hole in the ground, about nine or ten feet in depth. This they line with poles and sticks, making, in fact, a wall as of a house. A stout conical roof is then raised over the hole, and upon the roof earth is thickly strewn and beaten down, just as has been mentioned when treating of the ice-house. The only access to this strange house is by a circular aperture in the centre of the conical roof, serving at once the purpose of a door, a chimney, and a window. A notched pole answers as a ladder, a low wooden dais placed against the wall serves as a bed or a chair, for there is no other, and a few stones placed together act as a fireplace.
Inlooking at both these subterranean dwellings, I could not but be reminded of a very common insect which has a double dwelling, one moiety being aboveground, and the other moiety below it. This is the common Wood-ant (Formica rufa), whose large, leafy hills are so plentiful in some of our woods. On account of its size, this species is sometimes called the Horse-ant.
At first sight the nest looks something like a small haycock, made entirely of chopped grass. When examined more nearly, it will be found to consist mostly of grass-stems, little bits of stick, and leaves. Those of the fir are in great request, for when they are dry they are very light, and their form enables the Ant to interweave them with each other, so as to form the necessary tunnels and galleries which line the interior of the nest. The materials seem most unpromising, but they are used with wonderful skill, such as no human fingers could equal.
After a little while a number of entrances into the nest are visible. They are almost invariably sheltered by projecting leaves, which act as porches, so that when the nest is viewed from above, they are almost entirely hidden. Each of these openings runs into one of the main galleries of the nest, and from thence issues a perfect labyrinth of passages.
This, however, is only half the nest, for the galleries and tunnels extend far beneath the surface of the earth, and have sundry enlarged portions or chambers wherein the immature pupæ may lie during their period of helplessness.
Owing to the very loose structure of the upper nest, and the tendency of the earth to fall into the galleries of the lower nest, it is very difficult to obtain a trustworthy view of the interior. Perhaps I may here be allowed to extract a passage from my “Insects at Home,” the description of the nest and its interior having been written almost on the spot:—
“I have, however, succeeded in obtaining an excellent view into the interior of a Wood-ants’ nest, though it was but a short one. Accompanied by my friend Mr. H. J. B. Hancock,[B]I was visiting some remarkably fine Wood-ants’ nests near Bagshot. We took with us a large piece of plate glass, placed it edgewise on the top of an Ant-hill, and, standing one at each side, cut the nest completely in two, leaving the glass almost wholly buried in it.
[B]Now Sir Henry J. Burford Hancock, Chief Justice of Gibraltar.
[B]Now Sir Henry J. Burford Hancock, Chief Justice of Gibraltar.
“After the expiration of a few weeks, during which time the ants could repair damages, we returned to the spot, and, with a spade, removed one side of the nest as far as the glass, which then served as a window through which we could look into the nest. It was really a wonderful sight.
“The Ant-hill was honeycombed into passages and cells, in all of which the inhabitants were hurriedly running about, being alarmed at the unwonted admission of light into their dwellings. In some of the chambers the pupæ were treasured, and these chambers were continually entered by Ants, which picked up the helpless pupæ, and carried them to other parts of the nest where the unwelcome light had not shown itself.
“Unfortunately this view lasted only a short time. Owing to the partial decomposition of the vegetable substances of which the Ants’ nest is made, the interior is always hot and always moist. Now, the day on which we visited the nest happened to be a cold one, and, in consequence, the moisture of the nest was rapidly condensed on the inner surface of the glass, and in a few minutes completely hid the nest from view, leaving me only time to make a rapid sketch. Unfortunately some one discovered the plate of glass and stole it.
“Next time that I examine a Wood-ants’ nest, I shall takecare to insert the glass exactly east and west, and shall open its southern side towards noon on a hot sunshiny day, so that the rays of the sun may warm the glass and prevent evaporation.”
Many other creatures make subterranean dwellings, but the Wood-ant is remarkable for possessing a double dwelling, the two portions communicating with each other, and capable of being used according to the degree of heat required.
Wehave already seen how the Eddystone lighthouse was the precursor of many similar buildings all, like their predecessor, having their form copied, with more or less strictness, from the outlines of a tree-stem.
Image unavailable: NATURAL MOUNTAIN. ARTIFICIAL MOUNTAIN, OR PYRAMID.NATURAL MOUNTAIN. ARTIFICIAL MOUNTAIN, OR PYRAMID.
Another form of building which was intended for endurance, and, indeed, is the most enduring of all shapes, is the Pyramid.
We are all familiar with the simple, yet grand outlines of the Pyramids of Egypt, whose vast antiquity takes us back to the times of Isaac and Joseph, and which seem capable of resisting the effects of Time, the universal destroyer, for thousands of years yet to come.
We may ask ourselves what was the natural object from which the Pyramid was copied. The name itself, which is formed from a Greek word signifying fire, shows that a flame was thought to have furnished the idea of this form of building. I cannot, however, but think that the flame had little, if anything, to do with it, and that the real model may be found in the hills which have been formed by Nature.
Examples of the Pyramids and the Hills are given in the accompanying illustration.
Havingnow disposed of the chief points in Architecture, we take some of the subsidiary details.
Of late years, when the traffic between different continents has so largely extended itself, and when shipping has increased both in the numbers and dimensions of the vessels, it is absolutely necessary that we should have harbours and docks enlarged and multiplied sufficiently to meet the calls upon them.
Image unavailable: CADDIS. TEREBELLA. SERPULA. SUBMARINE MORTAR.CADDIS. TEREBELLA. SERPULA. SUBMARINE MORTAR.
Now, it is comparatively easy to construct a building on shore, for all the mortars and cements which are used for the purpose of fastening the stones together are applied when wet, and incorporate themselves with the stones as they dry. But to make a mortar which could be applied while the stones were under water, and would “set” while beneath the surface, was a task not easily to be overcome. Yet it has been done so effectively that at the present day we can build beneath the surface of the water as securely, though not as rapidly, as if the stones had been laid on dry ground.
Several such mortars are now known, and, as is so often the case with human inventions, have been anticipated in Nature.
We have already seen how the Caddis-worm of the freshwaters can cement together, while under water, the various materials of which its tubular house is formed. The different Sticklebacks perform similar feats, no matter whether they inhabit fresh or salt water.
All those who take an interest in the productions of the seashore will have noticed upon our coasts the flexible tube of the Terebella, with its curiously fringed ends. This tube, as any one may see at a glance, is composed of grains of sand and similar materials, fastened strongly together by a kind of cement exuded from the worm, and possessing the property of hardening under water. As on some of our coasts fragments of shell are used for the tube, the worm goes by the popular name of Shell-binder.
If one of these worms be taken out of its tube, placed in a vessel with sea-water and a quantity of sand, broken shells, and little pebbles, the mode of building will soon be seen. At the extremity of the head are a number of extremely mobile tentacles, and these are stretched about in all directions, seizing upon the particles of sand and shell, seeming to balance them as if to decide whether they are suitable for the tube, and then fixing them one by one with the cement which has already been mentioned.
Generally speaking, the Terebella works only in the evening, but, if it be hastily deprived of its tube, it cannot help itself, and is perforce obliged to work while it can. It is worthy of remark that the Terebella, although, as a rule, it lives in a tube all its life, is capable of swimming with the usual serpentine motion of marine worms, and, when taken out of its tube, rushes about violently, and soon exhausts itself by its efforts.
Along most of our rocky seashores may be seen vast quantities of a sort of hardened sand, penetrated with small tubes. On a closer examination this sand-mass is resolved into a congeries of tubes, matted and twisted together, and each being the habitation of a marine worm called the Sabella. This name is derived from a Latin word signifying sand, and is given to the worm in allusion to the material of which it makes its habitation.
Like the Terebella, the Sabella uses its tentacles for the purpose of building the tubes, which are much stiffer than those of the Terebella. They are strong enough, indeed, togive the feet a firm hold while traversing the rocks, and this, is a matter of no small moment when the tide is coming in, and the shore has to be regained without loss of time.
Then we have other marine worms, known as Triquetra and Serpula, which make tubes in a somewhat similar manner, but of very fine materials and very strong cement, so that the tube is nearly as hard as stone.
Space would fail me if I were to enumerate these creatures at greater length, but enough has been said to show that man’s invention of subaquatic cement has been anticipated in Nature by the inhabitants both of salt and fresh water.
Wenow come to the subject of Paint and Varnish. Putting aside their use as a means to increase the beauty of the object to which they are applied, we will view them in the light of preservatives, and acknowledge the truth of the old Dutch proverb, that “Paint costs nothing.” Certainly, when the wood to which it is applied is thoroughly dry from within, it not only costs nothing, but repays itself over and over again as a preservative of the wood, and a defence against moisture from without.
The instances in which Paint is applied to wood are too numerous to be mentioned. Perhaps some of my readers may remember the case of the naval captain who, on taking command of his ship, was supplied, according to custom, with exactly half the amount of paint required for her. The invariable etiquette had been that the captain supplied the remaining half at his own cost. But the officer in question was not at all disposed to be “put upon,” and was a thorn in the sides of the “Naval Lords.”
Finding, by actual measurement, that the paint supplied to him was only half the amount which was really needed for the ship, he sent his respectful compliments to the Admiralty, asking whether they wished the port or the starboard side of the ship to be painted, for that there was only enough paint for one half of the ship, and he awaited instructions as to which side of the vessel it was to be applied. He was impervious to “minutes,” “directions,” &c., and, as far as I remember, this very impracticable man got his way, and was supplied with the requisite amount of paint.
Longbefore man ever invented paint or varnish the Hive Bee had made use of it.
Every one who has kept bees knows how they always fasten the edge of the hive to the board, and stop up any crevices that may be left open. The material which they use for this purpose is not wax, but a substance called “propolis.” This term is composed of two Greek words, signifying a suburb, or the outskirts of a town, and is given to this stationary substance in consequence of the use which is made of it.
Image unavailable: BEE VARNISHING CELLS. PAINTER VARNISHING WOOD.BEE VARNISHING CELLS. PAINTER VARNISHING WOOD.
Not only do the bees use it for fastening the hives, but also for strengthening their combs. Wax is a very precious material, and the beautiful hexagonal structure of the bee-comb is intended for the purpose of combining the greatest amount of storing space with the least expenditure of material. The plates of wax of which the cells are composed are so thin that their edges would break down even under the feet of the bees as they passed over it, and accordingly the bees strengthen the edges of the cells with propolis, as any one may see by examining a piece of bee-comb. The propolis is of a darker colour than the wax, and has a peculiar varnish-like appearance.
The propolis, as distinguished from wax, is mentioned by Virgil in his Georgics:—
“Collectumque hæc ipsa ad munera glutenEt visco et Phrygiæ servant pice lentius Idæ.”—Georg.iv. 40.
“Collectumque hæc ipsa ad munera glutenEt visco et Phrygiæ servant pice lentius Idæ.”—Georg.iv. 40.
“Collectumque hæc ipsa ad munera glutenEt visco et Phrygiæ servant pice lentius Idæ.”—Georg.iv. 40.
It is evident that the propolis cannot be obtained from the same source as the wax. The latter is secreted by the beesunder little plates or flaps upon the abdomen, while the propolis is purely a vegetable exudation. It is obtained from many trees, the principal being the horse chestnut. All who have handled the buds of this tree are aware that they are covered with a viscous and very adhesive matter, which serves as a varnish or protection to the bud before the leaves are strong enough to break out. This is the material which the bees gather for their propolis, and at certain times of the year the chestnuts may be seen swarming with bees, all busily engaged in scraping off the varnish.
The Use of Tools a Distinction between Man and Beast.—All Men, however savage, use Tools, but none of the lower Animals can do so until taught by Man.—Tools needed to break up the Ground.—The Digging-stick of savage Life: its Use and its Efficacy in practised Hands.—Digging-sticks in Nature.—The Heart-urchin, and its Mode of digging in the Sand.—The Spade: its Shapes and Uses.—Natural Spades.—Fore-foot of the Mole and Mole-cricket.—The Aard-vark, the Ant-eater, and the Mattock.—Shears and Scissors a Sign of Civilisation, never being employed by Savages.—Mechanical Principle of Scissors, the Inclined Plane, the Lever, and the Cutting Edge.—Chinese Shears and the Pruning Scissors.—Use of the Inclined Plane.—The Diagonal Knife of the Guillotine.—The Shears in Iron-works.—The “Drawing Cut” of Swordsmen.—Jaws of the Turtle and Tortoise.—The Snapping Turtle and the Chicken Tortoise.—The Locust, the Cockchafer Grub, the Great Green Grasshopper, and the Wart-biter.—The Leaf-cutter Bees and their Nests.—The Chisel and Adze.—Structure of Rodent Tooth and Chisel.—Use of the hard Plate of Enamel or Steel.—Combination of hard and soft Materials.—Teeth of Hippopotamus and Hyrax.—Principle of the Adze.—Self-sharpening and Self-renewing Tools.—The Plane and Spokeshave.—Principle on which they are made.—The Spokeshave and its Uses.—The “Guard” Razor.—The Hoop-shaver Bee and its Nest.—Its natural Plane, and the Use which is made of it.
The Use of Tools a Distinction between Man and Beast.—All Men, however savage, use Tools, but none of the lower Animals can do so until taught by Man.—Tools needed to break up the Ground.—The Digging-stick of savage Life: its Use and its Efficacy in practised Hands.—Digging-sticks in Nature.—The Heart-urchin, and its Mode of digging in the Sand.—The Spade: its Shapes and Uses.—Natural Spades.—Fore-foot of the Mole and Mole-cricket.—The Aard-vark, the Ant-eater, and the Mattock.—Shears and Scissors a Sign of Civilisation, never being employed by Savages.—Mechanical Principle of Scissors, the Inclined Plane, the Lever, and the Cutting Edge.—Chinese Shears and the Pruning Scissors.—Use of the Inclined Plane.—The Diagonal Knife of the Guillotine.—The Shears in Iron-works.—The “Drawing Cut” of Swordsmen.—Jaws of the Turtle and Tortoise.—The Snapping Turtle and the Chicken Tortoise.—The Locust, the Cockchafer Grub, the Great Green Grasshopper, and the Wart-biter.—The Leaf-cutter Bees and their Nests.—The Chisel and Adze.—Structure of Rodent Tooth and Chisel.—Use of the hard Plate of Enamel or Steel.—Combination of hard and soft Materials.—Teeth of Hippopotamus and Hyrax.—Principle of the Adze.—Self-sharpening and Self-renewing Tools.—The Plane and Spokeshave.—Principle on which they are made.—The Spokeshave and its Uses.—The “Guard” Razor.—The Hoop-shaver Bee and its Nest.—Its natural Plane, and the Use which is made of it.
AMONG the many points of distinction between man and the lower animals, we may consider the use of tools as one of the principal lines of demarcation. Man stands absolutely alone in this respect. There is no race of savages, however degraded they may be, that does not employ tools of some kind, and there is no beast, however intelligent, that ever used a tool except when instructed by man.
As to the stories that are told of the larger apes using sticks and stones by way of weapons, they are absolutely without foundation, no animal employing any tool or weapon save those given to them by Nature. It is true that a monkey maysometimes be seen to take a stone for the purpose of cracking nuts which are too strong for its teeth, and to perform that task with great deftness; but such animals have always been taught by man, and had they remained in their own country, not one of them would have used a stone, were the nuts ever so hard.
Wewill begin our notice of tools by taking that which must have been the first tool invented by man. One of the principal duties assigned to man is the culture of the earth, and this he cannot do without tools, increasing their number and improving their structure in proportion to his own development in agriculture.
Before seed can be sown, it is necessary that the earth should be broken up, and, owing to the structure of the human frame, this task cannot be fulfilled by man without a tool which will enable him to rival many of the lower animals,i.e.make use of those digging appliances which have been furnished by Nature.
Image unavailable: HEART-URCHIN. DIGGING-STICK.HEART-URCHIN. DIGGING-STICK.
It is evident that the first earth-breaking tool must have been a pointed stick, and we find that in Southern Africa, in parts of Asia, and in Australia the Digging-stick is still in use for the purpose of breaking up the ground. The Australians are wonderful adepts in the use of the Digging-stick, which is one of the simplest of instruments, being merely a stick some two feet in length, pointed at one end, and the point hardened in the fire.
The mode of using it is by holding it perpendicularly, pecking it into the ground, and throwing out the loosened soil with the hands. In this way they can excavate with suchrapidity, that a strong navvy, armed with the best spade, would not be able to keep pace with a black man armed only with his “katta,” or digging-stick.
In Africa the Digging-stick is used in exactly the same manner, and is generally made more weighty and effective by having a perforated stone fastened on the handle.
Here, again, man has been anticipated by Nature, and the savage of Australia or Africa digs in exactly the same manner as the common Heart-urchin of our shores, sometimes called the Hairy Urchin, in consequence of the number and fineness of the spines, which look just like hairs to the naked eye. The scientific name of this creature isAmphidotus cordatus.
Mr. Gosse, in his “Evenings at the Microscope,” gives so admirable an account of the mode of digging employed by the Hairy Urchin that I cannot do better than employ his own words. After describing the variety of structure of the different spines with which the shell is so thickly set, he proceeds as follows:—
“But what is the need of so much care being bestowed upon the separate motion of these thousands of hair-like spines, that each should have a special structure, with special muscles for its individual movement? The hairs of our head we cannot move individually: why should the Heart-urchin move his?”
“Truly, these hairs are the feet with which he moves. The animal inhabits the sand at the bottom of the sea in our shallow bays, and burrows in it. By going carefully, with the lens at your eye, over the shell, you perceive that the spines, though all formed on a common model, differ considerably in the detail of their form. I have shown you what may be considered the average shape, but in some, especially the finer ones that clothe the sides, the club is slender and pointed; in others, as in those behind the mouth, which are the largest and coarsest of all, the club is dilated into a long, flat spoon; while in the long, much-bowed spines, which densely crowd upon the back, the form is almost uniformly taper throughout, and pointed.”
“The animal sinks into the sand mouth downwards. The hard spoons behind the mouth come first into requisition, scooping away the sand, each acting individually, and throwing it outwards. Observe how beautifully they are arranged forthis purpose, diverging from the median line, with the curve backwards and outwards.
“Similar is the arrangement of the slender side spines; their curve is still more backwards, the tips arching uniformly outwards. They take, indeed, exactly the curve which the fore-paws of a mole possess,—only in a retrograde direction, since the Urchin sinks backwards,—which has been shown to be so effective for the excavation of the soil, and the throwing of it outwards.
“Finally, the long spines on the back are suited to reach the sand on each side, when the creature has descended to its depth, and by their motion work it in again, covering and concealing the industrious and effective miner.”
The reader will notice that this mode of digging is exactly like that which is followed by the users of the Digging-stick, the earth being first broken up, and the loosened portions thrown aside. The whole of the description of the spines is exceedingly interesting, but, as it does not bear directly on the present subject, I cannot admit it into these pages.
Nowcomes another development in digging tools.
We have already seen how effective an instrument a mere piece of stick can be in the hands of a skilful workman, and the manner in which it can tear up a given depth of soil. But, for agricultural purposes, something more is needed, and the ground must not only be broken up, but a certain regularity must be observed, in order to allow space to be accurately measured, and the crop apportioned to the area.
Out of the Digging-stick, then, the Spade was developed, its chief advantage being that it dispensed with the use of the bare hands, and not only tore up the ground, but threw out the loosened soil.
The reader will remember that in the preceding description of the Heart-urchin it was mentioned that many of the spines are shaped at their ends something like spoons, and that their comparatively wide blades are used in scraping the sand and shovelling it aside. In fact, these flattened spines are natural spades, used on the same principle as the modern spade of civilisation.
On the right hand of the illustration are shown two forms ofspade, the one being the ordinary garden tool, and the other a rather curious implement which is in great use among the metal mines of Cornwall. The use of the ordinary spade is too familiar to need explanation, and we come to the Miner’s spade. This implement is used rather as a shovel than as a spade, the peculiar bend near the blade preventing the foot from being used as a means of forcing the instrument into the ground. In fact, it is not meant for the same office as that which pertains to the ordinary spade, neither can it be handled in the same way.
Image unavailable: FOOT OF AARD-VARK. FOOT OF MOLE-CRICKET. SPADES. FOOT OF MOLE.FOOT OF AARD-VARK. FOOT OF MOLE-CRICKET. SPADES. FOOT OF MOLE.
In Devonshire there is a kind of spade in general use very much resembling the mining spade, but having a very long handle without any crutch at the end. The natural consequence of this shape is, that the spade cannot be used in the ordinary way, neither can it penetrate the earth to any depth. It can “peel” the ground, so to speak, and can cut away successive layers of soil. But as for digging “two spits deep,” or even one spit, the spade would be absolutely incapable of such a task, no matter how strong might be the hands that wield it. As for the foot, it may be put out of the question.
Wewill now turn to a few examples of spades in the world of Nature.
The lowest figure represents the fore-paw of the Mole,with its powerful armature of strong and sharp claws, and its broad blade of a palm. The reader will easily see that in this animal the digging powers are wonderfully developed. The peculiar form of the fore-foot closely resembles that of the miner’s spade, while the curvature of the palm serves, almost without exertion, to throw out the earth which has been scooped away by the sharp claws.
To watch a Mole burrow is really a curious sight, the only drawback being that the animal sinks itself so rapidly beneath the earth that a long inspection is impossible. I have kept several moles for the purpose of watching their habits, and have always been interested in their mode of burrowing. I can only define it by using the word “scrabbling.” The animal scurries and hurries about, seeking for a tolerably soft piece of ground. When it has found one, it travels no further, but scratches away with its fore-paws with wonderful power and rapidity, seeming to sink, as it were, into the earth, rather than to excavate a tunnel.
Thereis an insect well known to entomologists, called the Mole-cricket, because its structure and many of its habits are strangely similar to those of the animal from which it derives its name. At the upper part of the illustration is seen a portion of the fore-foot of the Mole-cricket, and a better implement of excavation can hardly be imagined.
The reader will probably have noticed that in both these creatures the spade, if we may so call it, is not a mere flat plate, but is cleft into several points. It thus answers the purpose of a fork as well as a spade, the several points serving to break up the soil, and the flat palm to throw the earth aside.
This principle is carried out even more fully in the fore-paw of the African Ant-bear, or Aard-vark (Orycteropus Capensis), a figure of which is given in the illustration. This animal is a great excavator, living in burrows of such dimensions that the wild boar is in the habit of making its home in them after they are deserted.
Something more, however, than a digging apparatus is needed for the Ant-bear. This animal feeds almost wholly on the Termites, which it obtains by tearing down the walls oftheir dwellings. Now, as these wonderful buildings are nearly as hard as brick, and, indeed, are composed of the same materials, it is necessary that the claws of the Ant-bear should be modified so as to be able to break through the walls. Accordingly, they are much more curved than those of the Mole and the Mole-cricket, and so serve for tearing as well as digging, being struck into the wall, and thus pulling it down, just as a labourer breaks down a bank with his mattock.
Indeed, had we wished to extend these analogies still further, we might easily have given the claws of the Aard-vark as a prototype of our English mattock. The same weapons as possessed by the Ant-bear of tropical America are used in exactly the same manner, but are even stronger, and extend to such a length that when the animal walks, it cannot stretch its claws out in front, but is obliged to double them under its feet.
Theseinstruments are sure signs of civilisation, no savage nations having the least idea of them. Even the Kafir and Esquimaux tribes, which are such admirable workers in skin, never use scissors in shaping their garments, but invariably employ knives for that purpose. The Chinese, however, seem to have known scissors from time immemorial, and to have shaped them almost exactly like our own instruments. I possess one pair of tailor’s shears from China in which there is only one ring, namely, that for the thumb. The place of the other ring is taken by an elongated, slightly curved and moderately pointed rod of steel, which is used for tracing the pattern on the material preparatory to cutting it.
Simple as the scissors may seem, they combine several very important principles, namely, the inclined plane, the lever, and the cutting edge. Were they to be merely two edges moving directly upon each other, their effect would be comparatively slight; but, owing to the manner in which the blades are fixed at one end, they are drawn as it were over the object between them, and so divide it with comparative ease. In some instruments, such as the pruning scissors, there is only one cutting blade, the other being used merely as a support for the branch which is being cut.
A well-known example of a single cutting blade is found in the guillotine. In the earliest times of this invention an ordinary axe-head was suspended above the neck of the criminal. It was found, however, that its operation was very uncertain, simply because the blow was a direct one, and not oblique. The blade was then set obliquely, as in the present machine, and its effect was absolutely certain.
Perhaps some of my readers may be swordsmen, and therefore know the power of the “drawing cut,” by which a great effect may be produced with very little apparent exertion. Even in the simple operation of cutting bread we always use the knife diagonally, though perhaps we may be ignorant of the principle of the inclined plane.
Next comes the principle of the lever, as exemplified by the handles of the scissors. By lengthening these handles, the power of the blades is enormously increased, as may be seen in the various shears in any great iron-works, which cut through thick iron as if it were butter. Our own garden shears for trimming borders show very well the power of the long arms and short blade.
Inthe animal world we find many examples of natural shears, one of the best of which is afforded by the jaws of the Tortoise or Turtle. Owing to the manner in which they feed, whether they be vegetarians or carnivorous, their jaws are made for cutting, and not for lacerating or mastication. They have no teeth, but each jaw is furnished with a horny edge, as sharp as a knife-blade, and very strongly made. With these jaws the animal can shred to pieces the objects which it attacks, just as if it had been furnished with a pair of veritable shears. Any one who has possessed an ordinary Tortoise must have noticed the havoc which it will occasionally make in a garden. I had one of these reptiles for some years, and was obliged to keep it under restraint, in consequence of the power of its jaws.
Being a Tortoise of discrimination, it took a great fancy to the strawberry beds, and invariably picked out the ripest and best-flavoured fruit. Reversing the usual proverb of making two bites at a cherry, the Tortoise always took two bites at a strawberry, and sometimes three or four, according to its size.
At last, I was obliged to restrain it by boring a hole in theedge of its shell, passing one end of a string through it, and fastening the other to a peg driven into the ground. At first, I tied the string to a brick, but the Tortoise was so strong that it dragged the brick about the garden, leaving reminiscences of its progress in the channels which it had cut through all kinds of vegetation with its scissor-like jaws.
Image unavailable: JAWS OF TURTLE. SHEARS.JAWS OF TURTLE. SHEARS.
The reader, in comparing the illustration of the Turtle-jaws with that of the Shears, will see at once how exact is the analogy between the two. The sharp-edged jaws correspond with the blades of the shears, the joint at the skull corresponds with the pivot of the shears, and the muscles which move the jaws, but which could not be shown in the present illustration, are the prototypes of the handles.
In some of these creatures, especially those which are carnivorous, the power of the jaw is tremendous. One of them, a Snapping Turtle, has been known to bite off several fingers of a man’s hand as easily as if they had been carrots. Some years ago I kept some Chicken Tortoises alive, and was much struck with the enormous proportionate power of their jaws.
They were quite little creatures, only a few inches in length, but their appetites were astonishing, and their mode of satisfying their hunger remarkable. They were always ravenous after meat, and had a curious way of seizing their food in their mouths, placing one paw on either side of their jaws, and then pushing the meat forcibly away, so as to cut out a slice as large as their jaws.
They were very good-tempered little things, but, small though they were, I should have been very sorry to have one of them take a bite at my finger by mistake.
Knowing their general characteristics, I took care not to have any living creature in the same vessel. But I have heard, from those who have had practical experience, that Chicken Tortoises ought to be banished from any place wherein fish are kept, especially if they be gold fish, the Tortoise having a way of coming quietly beneath them, biting out a mouthful of their bodies, and then disappearing with its booty.
Besidethe Tortoise, there are many creatures which possess natural shears, such as the Locust, whose ravages are only too notorious. Then, taking our own country, we have plenty of examples of insect shears. Such is to be found in the jaws of the Cockchafer larva, or “White Grub” as it is popularly called. It lives underground, and feeds chiefly on the roots of herbage, shredding them to pieces with its shear-like jaws. And, as it spends on the average three years in the one task of perpetual eating, the damage which it does can be easily imagined.
There is a very pretty English insect which admirably exemplifies the power of the natural scissors. This is the Great Green Grasshopper (Acrida viridissima), which is equally voracious in all its stages of existence. It is always ready to use these jaws, and I do not recommend the reader to allow his finger to get between them, or their points will probably meet.
One of these insects, indeed (Decticus griseus), has derived the name of Wart-biter from its supposed use in curing warts. All that was needful was to catch a Wart-biter, and hold one of the warts to its jaws. It was sure to seize the wart, and bite it smartly, and there was a firm belief that any one thus bitten would be freed from the unsightly excrescence. The bite of the shear-like jaws caused much pain at the time, and this very pain had in all probability something to do with the cure.
Anadmirable example of the insect jaws used as scissors is to be found in the well-known Leaf-cutter Bees, insects belonging to the genus Megachile.
They make their nests in burrows, sometimes in wood, and sometimes in the ground, and form them in a very singular manner. After fixing upon a suitable burrow, the Bee goes offto a tree, generally a rose, and, using her jaws just as a tailor uses his shears, cuts off a nearly semicircular piece of leaf, flies away with it to her home, and, by dint of bending, pushing, and pulling it, she forces it to the bottom of the cell. Successive pieces of leaf follow, until she has made a thimble-shaped cell, and she then places at its end an egg and a supply of honey and pollen.
Cell after cell succeeds, each being introduced into its predecessor just as thimbles are packed. Judging from a specimen in my collection, there are about eight layers of leaves to form the walls of the cell, and the average length of each piece of leaf rather exceeds half an inch. The entire length of the cell-group is two inches and a half. The leaf-slices are always cut from the edge, and, in my specimen of the nest, the serrated outer edges of the leaves are all in one direction.
Should any of my readers find one of these nests, it will be as well for them to dip a needle point into diamond cement, and introduce it under the outermost coating of leaves. Otherwise, when the leaves are dry, and the insects break their way into the open air, the cells will probably fall to pieces.
These Bees are much more abundant than is usually thought. In summer-time it is hardly possible to find a rose-bush on which are not a number of leaves from which pieces of variable size and shape, but always with a curved outline, have been cut as with scissors. While cutting them, the Bee seems to trace out her pattern, as it were, by using her feet like one leg of a pair of compasses, and her head as the other leg. As soon as she has nearly finished the operation, she poises herself on the wing, to prevent her weight from tearing away the leaf irregularly, and then, while still on the wing, makes the last few bites, and severs the leaf entirely.
Alreadywe have seen how exact is the analogy between the scissors and the turtle-jaw. As we are upon the subject of cutting instruments, we will continue it, trying to discover some further analogies.
On the right hand of the illustrations we see three cutting tools made by human hands—i.e.the Chisel, the Stone Adze ofPolynesia, and the Steel Adze of this country. We begin with the Chisel.
All those who have even a slight knowledge of anatomy know how curiously exact is the resemblance of the Chisel of civilised life to the front tooth of any Rodent animal. The head of the Beaver is here given as an example, but the tooth of a mouse, rat, or rabbit, which can easily be obtained, is quite as good an example. These teeth are made after a very beautiful fashion. Their outer surface is covered with a plate of very hard enamel, while the rest of the tooth is of bony matter, and comparatively soft. Consequently, when the tooth is used, the enamel plate forms a sharp edge, while the rest of it is worn away, thus keeping the chisel-like end in its proper form.
Image unavailable: TOOTH AND JAWS OF BEAVER. CHISEL.TOOTH AND JAWS OF BEAVER. CHISEL.
The power of these teeth may be appreciated by any one who has been bitten even by so small a rodent as a mouse, the sharp edges meeting in the flesh, and causing a very painful wound. When the teeth are large, as in the Beaver, and the jaws powerful, their force is something wonderful, tree-trunks of considerable size being cut down quite easily.
Perhaps some of my readers may not be aware that the Chisel is constructed on exactly the same principle as the tooth of the Rodent animal. It is not entirely made of steel, as is generally thought. In the first place, a valuable material would be needlessly wasted, and, in the next place, the tool would not keep its edge except with infinite labour in grinding.
The principal part of the Chisel-blade is therefore made of soft iron, a very thin plate of steel running along the back. This plate answers the same purpose as the enamel in the tooth, while the soft iron takes the place of the soft bone. Axe-blades, which are, in fact, formed like two chisels placed back to back, are made on a similar principle, except that the steelplate occupies the centre of the blade, and the soft iron is on either side. Thus the thin plate of steel is easily brought to an edge, while the soft iron can be ground away without any difficulty.
I do not mean to state that the inventor of this combination of thin steel and soft iron had taken his idea from the Rodent tooth, but only to show that the invention, beautiful, simple, and ingenious as it is, has its prototype in Nature. I may here mention that the Plane-iron, which is, in fact, a modified Chisel, is made in exactly the same fashion.
Nextwe come to the Adze.
Image unavailable: ADZE-TEETH OF HIPPOPOTAMUS. STONE ADZE OF POLYNESIA. STEEL ADZE.ADZE-TEETH OF HIPPOPOTAMUS. STONE ADZE OF POLYNESIA. STEEL ADZE.
In some respects there is much resemblance between the blade of the Adze and the teeth of the Rodent, especially in their curve, which is almost identical in both. This form is seen in the structure of other teeth than those of Rodents. There is, for example, the tooth of the Hippopotamus, which is not only curved, like that of the Rodent, but bevelled off in a similar way at the tip. With these formidable teeth, one of which is now before me, the Hippopotamus makes terrible havoc among the herbage, mowing it down, so to speak, and stowing it away wholesale in its enormous stomach. A Hippopotamus indeed, when angered, has been known to sever a man’s body completely in two with a single bite, so trenchant are the teeth, and so powerful the jaws.
Then there is a little animal called the Hyrax, or Rock-rabbit, which is the coney of Scripture. This creature is really one of the pachydermatous group, although its small size, hairy coat, its activity among the rocks, and its apparently rodentteeth, have induced many persons to place it among that group. These teeth, however, like those of the Hippopotamus, are bevelled off at their tips, and, as they perform a similar office, they take a similar curve.
It is worthy of notice that in the Stone Adze the bevelled edge much more resembles the rodent tooth than does the Steel Adze, the reason being evidently that stone is more fragile than steel, and requires greater thickness. Still, the principle is the same in both, only the metal is more attenuated than the stone.
The Rodent or Hippopotamus tooth has still a great advantage over any chisel or adze made by man, whether of stone or metal. As our tools are blunted, we are forced to spend much time in sharpening them, and by degrees grind the tool away until it becomes useless. Now, the teeth are so arranged that their perpetual use, instead of blunting, only sharpens them, and in proportion as they are worn away in front they are supplied with fresh matter from behind, and perpetually pushed forwards, so that they are self-renewing as well as self-sharpening.
I havealready made mention of the Plane in connection with the Chisel, and shown that, like that tool, it is formed on the same principle as the Rodent tooth.
The use of this important instrument in carpentering cannot be overrated, as is shown by the numberless varieties which are used by carpenters, and the different uses to which they are put, sometimes merely smoothing a level surface, and sometimes forming a “moulding” where ornament is required.
In principle, a Plane is a cutting edge or chisel, pushed along the object to be worked, and, the edge being guarded, taking off a very thin shaving from the surface.
On the right hand of the accompanying illustration is shown the Plane in action, with the thin shavings falling from it in curled masses. Perhaps some of my readers may have visited some of the great iron-works, and been struck with the use of the Plane as applied to metal instead of wood, long ironshavings being taken off as easily as if they were deal, and curling in just the same manner.
Thereis an instrument very familiar to carpenters, called the Spokeshave, on account of its use in trimming the spokes of wheels. Different as it may be in appearance, it is identical in principle with the plane, having an edge guarded by a piece of wood, so that the blade cannot cut too deeply into the object on which it is employed. The chief distinction, indeed, is, that the workman, instead of pushing the blade from him, draws it to him.