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Nature's Teachings: Human Invention Anticipated By Nature

J. G. (John George) Wood

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NATURE’S TEACHINGS HUMAN INVENTION ANTICIPATED BY NATURE

NATURE’S TEACHINGS HUMAN INVENTION ANTICIPATED BY NATURE

BY THE LATE REV. J. G. WOOD, M.A., F.L.S., Etc. AUTHOR OF “HOMES WITHOUT HANDS,” “MAN AND BEAST, HERE AND HEREAFTER,” ETC. NEW AND REVISED EDITION LONDON J. S. VIRTUE &amp; CO., Limited , 26, IVY LANE PATERNOSTER ROW LONDON: PRINTED BY J. S. VIRTUE AND CO., LIMITED. CITY ROAD....

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PREFACE.

PREFACE.

A GLANCE at almost any page of this work will denote its object. It is to show the close connection between Nature and human inventions, and that there is scarcely an invention of man that has not its prototype in Nature. And it is worthy of notice that the greatest results have been obtained from means apparently the most insignificant. There are two inventions, for example, which have changed the face of the earth, and which yet sprang from sources that were despised by men, and thought only f

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The Raft.

The Raft.

I T has been frequently said that the modern developments of science are gradually destroying many of the poetical elements of our daily lives, and in consequence are reducing us to a dead level of prosaic commonplace, in which existence is scarcely worth having. The first part of this rather sweeping assertion is perfectly true, but, as we shall presently see, the second portion is absolutely untrue. Science has certainly destroyed, and is destroying, many of the poetic fancies which made a par

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The Boat.

The Boat.

There is no doubt that the first idea of locomotion in the water, independently of swimming, was the raft; nor is it difficult to trace the gradual development of the raft into a Boat. The development of the Kruman’s canoe into the Great Eastern , or a modern ironclad vessel, is simply a matter of time. It is tolerably evident that the first raft was nothing more than a tree-trunk. Finding that the single trunk was apt to turn over with the weight of the occupant, the next move was evidently to

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NAUTICAL. CHAPTER II. THE OAR, THE PADDLE, AND THE SCREW.

NAUTICAL. CHAPTER II. THE OAR, THE PADDLE, AND THE SCREW.

Propulsion by the Oar.—Parallels in the Insect World.—The “Water-boatman.”—Its Boat-like Shape.—The Oar-like Legs.—Exact mechanical Analogy between the Legs of the Insect and the Oars of the human Rower.—“Feathering” Oars in Nature and Art.—The Water-boatman and the Water-beetles.—The Feet of the Swan, Goose, and other aquatic Birds.—The Cydippe, or Beroë.—The Self-feathering Paddle-wheel.—Indirect Force.—The Wedge, Screw, and Inclined Plane.—“Sculling” a Boat.—The “Tanka” Girls of China.—Mechan

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NAUTICAL. CHAPTER III. SUBSIDIARY APPLIANCES.—Part I.

NAUTICAL. CHAPTER III. SUBSIDIARY APPLIANCES.—Part I.

General Sketch of the Subject.—The Mast of Wood and Iron.—Analogy between the Iron Mast and the Porcupine Quill.—The Iron Yard and its Shape prefigured by the same Quill.—Beams of the Steam-engine.—Principle of the Hollow Tube in place of the Solid Bar.—Quills and Bones of Birds.—Wheat Straws and Bamboos.—Structure of the Boat.—The Coracle, the Esquimaux Boat, and the Bark Canoe.—Framework of the Ship and Skeleton of the Fish.—Compartments of Iron Ship and Skull of Elephant.—The Rush, the Cane,

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NAUTICAL. CHAPTER IV. SUBSIDIARY APPLIANCES.—Part II.

NAUTICAL. CHAPTER IV. SUBSIDIARY APPLIANCES.—Part II.

The Cable and its Variations.—Material of Cables.—Hempen and Iron Cables, and Elasticity of the latter.—Natural Cables.—The “Byssus” of the Pinna and the common Mussel.—The Water-snail and its Cable.—A similar Cable produced by the common White Slug.—The Principle of Elasticity.—Elastic Cable of the Garden Spider.—Tendrilous Cables of the Pea and the Bryony.—The Vallisneria, and its Development through the Elastic Cable.—Proposed Submarine Telegraph Cable.—The Anchor, Grapnel, and their Varietie

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NAUTICAL. CHAPTER V. SUBSIDIARY APPLIANCES. Part III.—The Boat-hook and Punt-pole.—The Life-buoy and Pontoon-raft.

NAUTICAL. CHAPTER V. SUBSIDIARY APPLIANCES. Part III.—The Boat-hook and Punt-pole.—The Life-buoy and Pontoon-raft.

The Boat-hook and its varied Uses.—The Earth-worm and the Serpula.—Microscopic Boat-hooks.—The Life-belt.—Life-boats and their Structure.—Uses of Cork.—Wine Corks made serviceable.—The Life-collar.—Portuguese Man-of-war.—Captain Boyton’s Life-dress.—The Life-raft.—Victualling a Yacht and Boat.—The Janthina and its Air-vessels.—Cask-pontoon—Pottery-raft and its Uses. A S all rowing men know, an indispensable appliance to the boat is the Boat-hook, which can be used either as a pole, wherewith to

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The Pitfall.

The Pitfall.

One of the simplest examples of this double use is afforded by the Pitfall, which is employed in almost every part of the world, and, although mostly used for hunting, still keeps its place in warfare. On the right hand of the accompanying illustration is shown a section of the Pitfall which is so commonly used in Africa for the capture of large game. It is, as may be seen, a conical hole, the bottom of which is armed with a pointed stake. Should a large animal fall into the pit, the shape of th

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The Club.

The Club.

The simplest of all offensive weapons is necessarily the Club . At first, this was but a simple stick, such as any savage might form from a branch of a tree by knocking off the small boughs with a stone or another stick. Such clubs are still used in Australia, and I have several in my collection. Then the inventive genius of man improved their destructive power by various means. The most obvious plan was to add to the force of its blow by simply making one end much thicker and heavier than the o

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The Sword.

The Sword.

The next improvement on the club was evidently to flatten it, and sharpen one or both edges, so as to make it a cutting as well as a stunning implement—in fact, the club was changed into a Sword . A good example of this weapon in its simplest form is the wooden sword of Australia, now an exceedingly rare weapon. It looks like a very large boomerang, but is nearly straight, and is made from the hard, tough wood of the gum-tree. Travellers say that the natives can cut off a man’s head with this ve

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The Spear and the Dagger.

The Spear and the Dagger.

It is tolerably evident that the invention of the spear and dagger must have been nearly, if not quite, contemporaneous with that of the club. I place these weapons together because there is great difficulty in assigning to either of them the precedence, the spear being but a more or less elongated dagger, and the dagger a shortened spear. As a good example of this fact, I have in my collection a number of spears and daggers belonging to the Fan tribe of Western Africa. In every case the weapons

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Animal Poisons.

Animal Poisons.

Perhaps the most diabolical invention of this kind was the Venetian stiletto, made of glass. It came to a very sharp point, and was hollow, the tube containing a liquid poison. When the dagger was used, it was driven into the body of the victim, and then snapped off in the wound, so that the poison was able to have its full effect. Such poisons are of different kinds, and invariably animal or vegetable in their origin. Taking the animal poisons first, we come to the curious mode of poisoning the

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Vegetable Poisons.

Vegetable Poisons.

We now come to the Vegetable Poisons, the two best known of which are the Upas poison of Borneo, and the Wourali of South America. It is rather remarkable that in both these cases the arrows are very small, and are blown through a hollow tube, after the manner of the well-known “Puff-and-dart” toy of the present day. The Upas poison is simply the juice of the tree, and it does not retain its strength for more than a few hours after it has been placed on the arrow-points. A supply of the same liq

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Natural Animal Poisons.

Natural Animal Poisons.

Now , both in the animal and vegetable worlds may be found several examples of an apparatus which acts in exactly the same manner. The first is the poison-fang of the Serpent, a specimen of which is given on the left hand of the illustration. This fang answers in every respect to the syringe above mentioned. The long and slender fang is hollow, and answers to the pipe of the syringe. It communicates at the base with a reservoir of liquid poison, which answers to the body of the syringe, and ther

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Natural Vegetable Poisons.

Natural Vegetable Poisons.

So much for animal poisons. We will now pass to the vegetable world. Of the vegetable sting-bearers none are more familiar to us than the Nettle, three species of which inhabit this country. The two commonest are the Great Nettle ( Urtica diœcea ) and the Small Nettle ( Urtica urens ), and both of them are armed with venomous stings, which cause the plants to be so much dreaded. The structure of these stings is very simple, and can be made out with an ordinary microscope, or even a good pocket l

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The Barb.

The Barb.

We now come to another improvement, or rather addition, in the various piercing weapons. Sometimes, as in the case of the dagger or the hand-spear, it was necessary that when a blow had been struck the weapon should be easily withdrawn from the wound, so as not to disarm the assailant, and to enable him to repeat the stroke if needful. But in the case of a missile weapon, such as a javelin or an arrow, it was often useful, both in war and hunting, to form the head in such a way that when it had

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WAR AND HUNTING. CHAPTER III. PROJECTILE WEAPONS AND THE SHEATH.

WAR AND HUNTING. CHAPTER III. PROJECTILE WEAPONS AND THE SHEATH.

Propulsive Power.—The Pea-shooter and its Powers.—An Attack repulsed.—Clay Bullets.—Puff and Dart.—The Sumpitan of Borneo, and its Arrows.—The Zarabatana or Pucunha of South America, and its Arrows.—The Air-gun.—Modern Firearms.—The Chœtodon, or Archer-fish.—The Pneumatic Railway.—The Throwing-stick and its Powers.—Australians, Esquimaux, and New Caledonians.—Principle of the Sheath.—Waganda Spears.—Sheathed Piercing Apparatus of the Gnat, Flea, and Bombylius.—Indian Tulwar and Cat’s Claw.—The S

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The Net.

The Net.

A LTHOUGH the Net is but seldom employed for the purposes of general warfare, it was once largely used in individual combats, of which we will presently treat. In hunting, however, especially in fishing, the Net has been in constant use, and is equally valued by savages and the most civilised nations. To begin with the fisheries. Even among ourselves there are so many varieties of fishing-nets that even to enumerate them would be a work of time. However, they are all based on one of two principl

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The Rod and Line.

The Rod and Line.

That both terrestrial and aquatic nets should have their parallels in Nature is clear enough to all who have ever seen a spider’s web, or watched the “fan” of the barnacle. But that the rod and baited line, as well as the net, should have existed in Nature long before man came on earth, is not so well known. Yet, as we shall presently see, not only is the bait represented in Nature, but even our inventions for “playing” a powerful fish are actually surpassed. We will begin with the Bait. In near

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The Spring-trap.

The Spring-trap.

We are all familiar with the common Spring-trap, or Gin, as it is sometimes called. It varies much in form and size, sometimes being square and sometimes round; sometimes small enough to be used as a rat-trap, and sometimes large enough to catch and hold human beings, in which case it was known by the name of man-trap. This latter form is now as illegal as the spring-gun, and though the advertisement “Man-traps and Spring-guns are set in these grounds” is still to be seen, neither one nor the ot

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The Baited Trap.

The Baited Trap.

Our space being valuable, we are not able to give many examples of Baited Traps, whether in Art or Nature. The most familiar example of this trap is the common Mouse-trap, the most ordinary form of which is shown at the right hand of the illustration on page 96 . In all the varieties of these traps, whether for mice or rats, the prey is induced to enter by means of some tempting food, and then is secured or killed by the action of the trap. Sometimes these traps are made of considerable size for

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Birdlime.

Birdlime.

By a natural transition we pass to those traps which secure their prey by means of adhesive substances. With us, the material called “birdlime” is usually employed. This is obtained from the bark of the holly, and is of the most singular tenacity. An inexperienced person who touches birdlime is sure to repent it. The horrid stuff clings to the fingers, and the more attempts are made to clear them, the more points of attachment are formed. The novice ought to have dipped his hands in water before

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Reverted Spikes.

Reverted Spikes.

I am not quite satisfied with this title, but it is the best that I can find. By it I mean that mode of mechanism which, by means of an array of sharp spikes, permits an animal to enter a passage easily, and yet prevents it from emerging. Whether or not this principle be now employed in warfare I cannot say, but it is at all events used extensively in a small way of hunting, the best known of which is the wire Mouse-trap, one of which is shown at Fig. C on the illustration. A glance at the figur

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Spiked Defences.

Spiked Defences.

This mode of defence is, perhaps, one of the most primitive in existence, and takes a wonderful variety of forms. The spiked railings of our parks and gardens, the broken glass on walls, and even the spiked collars for dogs, are all modifications of this principle. On the illustrations are several examples of spikes used for military purposes. The first is known by the name of “Chevaux-de-frise,” and is extensively used in forming an extemporised fence where no great strength is needed. The stru

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Tearing Weapons.

Tearing Weapons.

We have already had examples of weapons, like the Club, which bruise; of weapons, like the Spear and Dagger, which pierce; and of weapons, like the Sword, which cut. We now come to a totally distinct set of weapons, those which wound by tearing, and not by any of the preceding modes. In civilised warfare we have long abandoned such weapons, as belonging to a barbarous age, but they are even yet employed in some parts of the world. The accompanying illustration shows three examples of such weapon

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The Hook.

The Hook.

H AVING now seen that the rod and line of anglers have their prototypes in Nature, we will proceed to the hook, by which the fish are secured. The two figures on the right hand of the accompanying illustration represent hooks which are familiar to every angler. The lower is the ordinary fish-hook, which can be used in so many ways. Generally it is employed singly, being fastened to the end of a line, and armed with a bait, either real or artificial. Sometimes, however, these hooks are whipped to

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Armour.

Armour.

We will now take the subject of Defensive Armour, by which warriors are enabled to protect themselves against the offensive weapons of the enemy. As many readers will probably know, armour reached its greatest development in the Middle Ages, when the knight was so completely cased in steel that no weapon then in use could penetrate his panoply. The head, body, and limbs were covered with steel plates curiously articulated at the joints, so as to give freedom of motion, while guarding the wearer

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The Fort.

The Fort.

As we have treated of one of the modes by which Forts were assaulted, we will now come to the Fort itself. The transitions in Fort-making are too curious to be omitted from the present book. As soon as war became organized, a Fort of some kind was necessary. The simplest mode of making a Fort was evidently to dig a deep trench, and throw up the earth on the inside, so as to form a wall. Let such a trench be square or circular, and there is a simple but powerful Fort, by means of which a comparat

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Scaling Instruments.

Scaling Instruments.

We have already seen how the Battering-ram could be worked against the walls of a fort, or how the assailants could scale them by means of the Testudo. There must, however, be occasions when it would be impossible to bring together a sufficiently large body of men to form the Testudo, or even to place ladders, and in such instances it would be necessary that each soldier should be furnished with an instrument by which he could haul himself up the wall. There are many examples still extant of suc

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Defence of Fort.

Defence of Fort.

So much for attack; now for defence. The simplest mode of defending a fort, or even a mountain pass, is by throwing or rolling rocks and heavy stones against the enemy. Simple as it may appear, it is a very effective one, as can be well understood by those who have rolled a huge stone down a long and steep slope. The stone goes gently enough at first, but rapidly gains speed, until at last it makes great bounds from the earth, tearing and crashing through everything as if it had been shot from a

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Imitation.

Imitation.

As is the case with the Norwegians, the Esquimaux have the greatest respect for the intellectual as well as the bodily powers of the Bear, and avowedly imitate it in its modes of hunting. One of these methods will now be mentioned. It must first be premised that the Seal is a most wary animal, and when it lies down on the shore to sleep, it takes its repose by snatches, lifting up its head at very short intervals, looking all round in search of foes, and then composing itself to rest again. To a

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The Fall-trap.

The Fall-trap.

This is a stratagem which is often employed in War and Hunting, though its use is mostly confined to the latter. Schoolboys often avail themselves of this principle when they wish to play a practical joke, and to amuse themselves by setting a “Booby-trap.” This trap is easily manufactured, and consists of a partially opened door, with a basin or jug of water balanced upon it. The natural result is, that any one who opens the door without proper precautions receives the jug and its contents upon

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Concealment.

Concealment.

W E will first take Concealment by means of Covering. If History repeats herself, so does Warfare. I have already shown the repetition of History in the Fortress—I shall now show it in the Field. In former days, when arms of precision were not invented, concealment was not needed. No soldier ever was visited with a dream so wild as that of taking definite aim at the enemy, and reserving the fire until the aim was certain. I have in my collection several of the French and English muskets used abo

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Disguise.

Disguise.

Next comes concealment by means of Disguise. On the right hand of the accompanying illustration is shown a singular mode of concealment adopted by the Barea, a warlike and predatorial tribe of Abyssinia. When Mr. Mansfield Parkyns was resident in Abyssinia he fell in with the Barea, through whose country he had to pass. “Scarcely had we passed the brook of Mai-Chena when one of our men, a hunter, declared that he saw the slaves. Being at that time inexperienced in such matters, I could see nothi

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The Trench.

The Trench.

We now come to a third mode of concealment in war, namely, that which is obtained by means of Trenches or Pits. Even in hunting the pit or partial trench is largely used. In Southern Africa the hunter often employs such a trench, called technically a “Skärm.” It is very simple in idea, and easily made, being based on the principle that lions, elephants, &amp;c., look for their assailants on the level of the earth, and seldom, if ever, look above or below it. Accordingly the hunter, having ma

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Gravity as a Propulsive Agent.

Gravity as a Propulsive Agent.

The two figures on the accompanying illustration will almost speak for themselves. We have already seen how the same force of gravitation which causes the avalanche to thunder down the precipice may be utilised as a means of projecting missiles in time of war. When, however, the stones or beams were once sent on their destructive mission, they were out of the control of those who launched them. We now come to a modification of the force of Gravity, by which the missile, if we may so term it, is

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Miscellanea.

Miscellanea.

By slow degrees, mankind, as they advance in civilisation, have robbed warfare of many horrors. Non-combatants, for example, are now left unharmed. Poisoned weapons have, by common consent, been abolished, and so have those instruments of warfare which, though they do not simply poison the blood by means of bodily wounds, do so by means of noxious vapours poured into the lungs. It is sometimes rather unfortunate when civilisation and semi-barbarism meet in battle; the former respecting the custo

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The Hut.

The Hut.

T HERE can be little doubt that mankind has borrowed from the lower animals the first idea of a dwelling, and it is equally true, as we shall presently see, that not only primitive ideas of Architecture are to be found in Nature, but that many, if not all, modern refinements have been anticipated. To begin at the beginning. The first idea of a habitation is evidently a mere shelter or roof that will keep off rain from the inhabitant. When Mr. Bowdich was travelling in Western Africa, he was told

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Floors and Pillars.

Floors and Pillars.

One decided step in Architecture is the invention of the Pillar, and its capabilities of aiding to sustain another floor above it. We see this principle carried out in our great cathedrals, where the use of the Pillar is almost infinite. Take, for example, Canterbury Cathedral. A heedless visitor might easily pass through the nave, enter the choir, visit the various side-chapels, and “Becket’s Crown,” without thinking that under his feet is a vast chamber, and that the floor on which he stands i

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Tunnel Entrance to the Dwelling.

Tunnel Entrance to the Dwelling.

We have already found occasion to treat of the snow-house, or igloo, of the Esquimaux, and have now to speak of a subsidiary, though necessary, part of Esquimaux architecture. Perhaps the reader may have been unfortunate enough to travel by rail in the depth of winter, and to be associated with fellow-passengers who will insist on closing every window, even though the carriage be crowded. Suppose that on such a day, the weather being perfectly fine, the train stops at a station, and the guard ou

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Doors and Hinges.

Doors and Hinges.

Having seen that both in Nature and Art the entrances to dwellings are guarded by tunnel-like approaches, we come naturally to another mode of guarding the entrance, namely, by a door moving on hinges. As to the multitudinous examples of doors and hinges in modern civilisation, we need hardly discuss them, except to show the exact analogies which occur in Art and Nature. Doors moving on hinges are very plentiful in Nature, even where we should least expect them. Take, for example, an egg, especi

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Mud Walls.

Mud Walls.

There is a mode of wall-building which is much in vogue in some parts of England, and has much to commend itself. This is the Mud or Concrete Wall. At first sight, the very name of a mud house gives an idea of poverty and misery, and is apt to be connected with hovels and pigsties. Mud walls, however, if properly built, are far warmer and drier than those of brick, and are even preferred to those of stone, when the latter can be easily and cheaply obtained. In Devonshire, for example, where even

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Porches, Eaves, and Windows.

Porches, Eaves, and Windows.

We now come to some of the appendages of a house, namely, the Porch by which the rain is kept from a doorway, the Eaves by which it is kept from the walls, and the Windows which will admit light and air, but will prevent the entrance of intruders. We first take the Porch, two examples of which are shown in the accompanying illustration, one being the work of human hands, and the other that of an insect. The figure on the right hand represents an old-fashioned Porch, such as is often to be seen a

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The Window.

The Window.

H AVING traced, though but superficially, the chief parts of a building, such as the walls, the door which is opened through the walls, and the roof which shelters them, we naturally come to the Windows by which light is admitted to them, and enemies excluded. There are, perhaps, few points in Architecture in which such changes have been made as in the Window, which, instead of being a difficulty in the way of the architect, is now valued as a means of increasing the beauty of the building. Taki

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Girders, Ties, and Buttresses.

Girders, Ties, and Buttresses.

Next in order come the means by which walls are supported internally by Girders and Ties, and externally by Buttresses. Of late years the Girder, in its many varieties, has come into general use, especially in the construction of railway bridges and similar edifices. On the right of the accompanying illustration is shown the Girder in its simplest form. The figure was taken from a Girder which is used in supporting the walls of a large building in Bermondsey. Sometimes a transverse stay connec

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The Tunnel used as a Passage.

The Tunnel used as a Passage.

As to this division of the subject, I have not been quite sure where it should be placed, but think the present position a tolerably appropriate one. We have already, in the igloo of the Esquimaux and the winter dwelling of the seal, found examples of the Tunnel when used as an appendage to the houses and a means of security. We now come to the Tunnel as affording the means of locomotion. Take, for example, our own railway system. Had it not been for the power of tunnelling, the railway would ha

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The Suspension-bridge.

The Suspension-bridge.

The mention of these Ants brings us to another point in architecture. We have already seen that they can not only build arched tunnels, but also can form their own bodies into arches, and we shall presently see how they can form themselves into Suspension-bridges. We will, however, first take the Suspension-bridge, and its vegetable origin, before passing to the animal. I have little if any doubt that the modern Suspension-bridge, with all its complicated mathematical proportions, was originally

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The Dam.

The Dam.

In many human operations, where a certain depth of water is required in a running stream, the reasoning powers of man have enabled him to attain his object by building a dam, or obstacle across the stream, which forces the water to rise to its level before it can find a passage. Such, for example, are the Locks which render rivers navigable, and allow even the heavily laden barges to traverse miles of water which would otherwise have been closed to them. Those mills, again, which are worked by w

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Subterranean Dwellings.

Subterranean Dwellings.

I do not intend in this place to take up the whole subject of Subterranean Dwellings, but only to point out cases where the use of the Subterranean Dwelling depends on the climate of the locality and the time of year, it being sometimes used and sometimes neglected, sometimes inhabited for the sake of warmth, and sometimes for that of coolness. In various parts of India there are some most remarkable Subterranean Dwellings. They are more than mere dwellings, and are, in fact, magnificent palaces

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The Pyramid.

The Pyramid.

We have 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. 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 se

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Subaquatic Mortar.—Paint and Varnish.

Subaquatic Mortar.—Paint and Varnish.

Having now 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. Now, it is comparatively easy to construct a building on shore, for all the mortars and cements

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The Spade.

The Spade.

We will 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 whic

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Shears and Scissors.

Shears and Scissors.

These instruments 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, th

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The Chisel and the Adze.

The Chisel and the Adze.

Already we 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 of Polynesia, 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 th

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The Plane and Spokeshave.

The Plane and Spokeshave.

I have already 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

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The Ribbon Saw, Cordon or Band Saw.

The Ribbon Saw, Cordon or Band Saw.

Perhaps some of my readers may be acquainted with a saw which has of late years come into extensive use—namely, the Ribbon Saw, Cordon Saw, or Band Saw. This is an endless steel band toothed on one edge, and passing over two wheels. It has the advantage of being of almost any breadth, some being several inches wide, while others are mere narrow ribbons, barely the sixth of an inch wide. The fretwork of pianos and other articles of furniture is cut almost exclusively by the Cordon Saw. A thick pi

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The Circular Saw.

The Circular Saw.

In one sense the Cordon Saw is a Circular Saw, but we now restrict the name to the tool which has a circular blade, more or less deeply toothed on the edge. The largest and coarsest of these saws are of enormous diameter, have teeth several inches in length, and can cut a large tree-trunk asunder in a wonderfully short time. There is a huge saw of this kind in Chatham Dockyard. It is kept in a sort of cellar covered with flap doors, where it really has the air of some dread monster lying in wait

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Boring Tools.

Boring Tools.

N EXT in importance to the edged tools which cut, come the pointed tools by which holes can be bored. We have an abundance of such tools, but they can all be reduced to two types, namely, those which, like the Bradawl, are forced between the fibres, and those which, like the Gimlet, cut away the material as they pass through it. They may, again, be shown to be different modifications of a single principle— i.e. that of the Wedge or Inclined Plane, which, as has already been shown, is identical w

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Striking Tools.

Striking Tools.

If we search the records of antiquity as left by races of men that have for countless ages vanished from the face of the earth, we shall find that in some shape or other the Hammer was a tool in constant use, and that in principle, though not in material, there was no difference between the Hammer of the Stone Age and that of a blacksmith of the present day. The development of the instrument can easily be traced, especially as it is a tool which does not admit of much elaboration. The original h

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Grasping Tools.

Grasping Tools.

Already we have spoken of the Shears and Scissors, together with their mode of action and dependence upon leverage. We now come to a set of tools which, although equally dependent on leverage, develop that power by grasping instead of cutting. Without these tools, the arts and sciences could have scarcely made themselves felt, as there are but few manufactures in which the artificer does not require a grasping power far superior to that of the human hand. Perhaps the enormous power of the Pincer

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Files and Sand-papers.

Files and Sand-papers.

H AVING now examined the analogies between the cutting, boring, striking and grasping tools of Nature and Art, we come to those finishing tools which smooth and polish the surface. The first is the File, an instrument which needs but little description. It consists of a surface of hardened steel, broken up into rough-edged teeth of infinite variety, according to the work which the file has to do. It is rather remarkable, by the way, that at present the English files are infinitely superior to th

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Tools of Measurement.

Tools of Measurement.

In many of the arts, more especially those which belong to engineering and carpentering as a part of architecture, it is absolutely necessary to make sure of a perpendicular line, i.e. a line which, if continued, would reach from any point of the earth’s surface to its exact centre below and its zenith above. Were it not for the power of producing this line, none of the great engineering works of modern or ancient days could have been undertaken. Take, for example, the wonderful tunnels which ha

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The Spirit-level.

The Spirit-level.

Having now seen how the forces of Nature enable us to produce a perfectly perpendicular line, we will see how the same force, though applied in a different manner, enables us to produce a perfectly horizontal line, the intersection of the two lines producing a right angle. The measuring tool in question is called the Spirit-level, and is represented on the right hand of the accompanying illustration. Its construction is very simple, consisting of a tube, nearly filled with spirit, and having jus

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Callipers.

Callipers.

We conclude the history of measuring tools with the Callipers. For ordinary purposes, and upon a plane surface, the Compasses answer every purpose. But there are various arts, especially sculpture, in which the compasses, with their straight legs, are absolutely valueless, and their place must be supplied by a differently shaped instrument. For example, no ordinary compasses could measure the exact distance from the nostril to the back of the head, or even touch two points at opposite sides of a

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The Camera Obscura and the Eye.

The Camera Obscura and the Eye.

I have already spoken of arts as being akin to each other. They are more than this, and every day of the world’s progress teaches us that Art, Science, and Manufacture are sisters, all born of one family, and all depending mutually on each other. Take, for example, our present theme—namely, Optics—and see how dependent it is upon Manufacture and Art. Without the former, man could not construct those beautiful telescopes, microscopes, spectroscopes, of the present day, which are evidently but the

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Long and Short Sight.

Long and Short Sight.

It has already been mentioned that the focus of a convex lens is shorter in proportion to its convexity, and that in consequence its magnifying power is increased. For example, the large glasses through which pictures are viewed are comparatively thin in proportion to their diameter, while the lenses employed for the highest powers of the microscope are scarcely larger than small shot, and nearly as globular. It naturally follows that any instrument to which a lens is adapted, whether it be micr

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The Stereoscope and Pseudoscope.

The Stereoscope and Pseudoscope.

Many persons have wondered how it happens that, as we have two eyes, we do not see two images instead of one. Practically, this is always the case, for the eyes, especially when they look on solid bodies, see two different images, because they contemplate the object from different points of sight. This may be easily ascertained by looking at a given object first with one eye, and then with the other, when it will be seen that the image presented to the right eye is slightly different from that o

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The Multiplying-glass.

The Multiplying-glass.

Still more extraordinary examples of the combining power of vision are to be found in the eyes of spiders and insects, more especially when we compare them with the work of man. If we take a common Multiplying-glass, such as is shown in the figure, and look at a flower or other object through it, we see the object repeated as many times as there are different foci of vision in the instrument. Now, taking for example the eyes of a Spider, it would be natural to suppose that the same result would

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The Water Telescope.

The Water Telescope.

E VERY one who has watched the movements of the various creatures which live below the surface of the water is aware how entirely dependent he is on the unruffled character of that surface. No matter how clear the water may be, the least ruffling of the surface will effectually shut out all sight:— And there is an end of the observations. If, however, the eyes can penetrate below the surface, the ruffling is of little consequence, so long as the water is clear. Consequently, whenever the top of

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The Iris of the Eye.

The Iris of the Eye.

I have often wondered, when contemplating the astonishing mechanism by which the Iris of the Eye is able to contract or enlarge the pupil according to the amount of light, whether any similar mechanism would be used in Art. As anatomists know, the Iris is composed of two layers. One consists of radiating fibres, which serve to enlarge the pupil, while the other layer surrounds the latter, and by its elasticity serves to contract it. As any one may see by looking in a mirror and shifting the ligh

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The Magic Lantern.

The Magic Lantern.

We are all familiar with the Magic Lantern, whether it may take the form of the mere child’s toy, be developed into Dissolving Views, or throw black shadows on a curtain, in which case it is called by the name of Chinese Shadows. In all these cases the principle is the same. First we have a light behind the object whose reflection is to be seen. Next we have the object itself, and lastly the surface upon which it is reflected. As to the variety of mirrors, lamps, and lenses which are used to pro

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The Spectroscope.

The Spectroscope.

Next we come to one of the most astonishing and beautiful optical instruments ever made by the hand of man. It is called the Spectroscope, because it deals with a certain arrangement of rays which is called a “spectrum.” Many years ago Newton discovered the cause of the lovely colours which deck the rainbow, and the fact that, by passing a ray of white light through a prism, it was decomposed into seven colours, which invariably came in the following order—Red, Orange, Yellow, Green, Blue, Indig

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The Thaumatrope.

The Thaumatrope.

Middle -aged persons will recollect that since the days of their childhood a great variety of optical apparatus has been invented ending in the word “trope.” This is a Greek word, signifying to turn, and is given to the instruments because they revolve. All these toys—and they may some day become more than toys—depend on a curious property of the human eye. The reader will remember that in the description of the human eye, as compared with the camera obscura as applied to photography, it was men

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Earthenware.

Earthenware.

The advent of real civilisation seems to depend largely upon the construction, not of weapons, but utensils, and the most useful of these are intended either for the preparation or the preservation of food. That such vessels should be made of earth is evident enough, and it is worthy of remark that the rude earthenware pot of the naked savage and the delicate china of Sèvres should both be products of the earth, and yet be examples of the opposite ends of civilisation. The most primitive earthen

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Ball-and-socket Joint.

Ball-and-socket Joint.

We will now see how some of the most useful mechanical inventions have had their prototypes in Nature. There is, for example, the well-known “Ball-and-socket joint,” without which many of our instruments, especially those devoted to optical purposes, would be impracticable. The figure on the right hand of the illustration represents the “bull’s-eye” of my own microscope. It will be seen that there is a ball half sunk in a cup, so that it can be turned in any direction. In point of fact, the uppe

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The Toggle or Knee Joint.

The Toggle or Knee Joint.

Another most useful invention now comes before us, called the Toggle-joint, or Knee-joint, the latter name being given to it on account of its manifest resemblance to the action of the human knee. This joint is shown in the illustration. It consists of two levers, jointed together at one end, and having the other ends jointed to the objects which are to be pressed asunder. It will be seen that if the centre of the Toggle be pushed or pulled in the direction of the arrow, so as to straighten the

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Crushing Instruments.

Crushing Instruments.

A S we are on the subject of leverage, we will take some examples of levers in Art and Nature, without, however, even attempting to exhaust the topic. On the right hand of the illustration is shown a very familiar example of a lever, namely, nut-crackers, with a nut between them. This useful implement is simply an adaptation of levers of the second kind, the power being represented by the human hand, the weight by the nut, and the fulcrum being the joint of the instrument. The common chaff-cutte

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The Rolling-mill.

The Rolling-mill.

We now come to another variation of the Crushing Machine, i.e. that in which the motion is constant, and not intermittent, as is the case with those machines which have just been mentioned. Perhaps some of my readers may have visited those great iron-works in which huge masses of iron are rolled into plates of greater or less thickness, or are cut up into strips as easily as if they were butter. The mechanism is in its principle simple enough. The cylindrical rollers are placed nearly in contact

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The Grindstone.

The Grindstone.

Being on the subject of jaws and teeth as a mode of breaking to pieces objects which are placed between them, we will take those implements which grind to powder, or “triturate,” instead of breaking or flattening. From the very earliest ages, and as soon as man had begun to discover the “staff of life,” the art of grinding naturally assumed an ever-increasing importance. The first and most primitive mode of grinding corn and converting it into meal was that which was followed by Sarah, when she

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Pressure of Atmosphere.

Pressure of Atmosphere.

There are many useful inventions which depend on the weight of the atmosphere and the creation of a more or less perfect vacuum. There is, for example, the common Pump, which raises water simply by the action of the atmosphere. A pipe passes into the water, and in that pipe an air-tight piston is inserted. When the piston is drawn upwards a vacuum is formed, and the water is at once forced into it by the pressure of the atmosphere. Then there is the graceful and useful Napier Coffee-making Machi

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Seed-drills.

Seed-drills.

Among the modern improvements in agriculture we may reckon the invention of the Seed-drill as one of the most important. By means of this invention, seed is greatly economized, the supply can be regulated, and the sower knows exactly where every grain of seed goes. There is no scattering, as in the wasteful broadcast plan, by which the seeds are flung almost at random over the field, and may or may not fall into the furrows. The Seed-drill, on the contrary, either stamps holes or ploughs narrow

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Cloth-dressing Machine.

Cloth-dressing Machine.

I N former days, when so much was done by hand that is now done by machinery, the thistle called the Teazle ( Dipsacus fullonum ) was of great value in British commerce, being used by countless thousands in the manufacture of broadcloth. When the woollen threads are woven so as to form the fabric of the cloth, there is no nap upon them, this having to be produced by a subsequent process. The plan of former days was, to procure a quantity of the seed-vessels of the Teazle, and dry them. They were

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Brushes.

Brushes.

It is worthy of notice that there are many articles of comparative luxury which could not be used until man had attained some degree of civilisation. Among these we may class the Brush and the Comb, no true savage ever troubling himself about either article. The Brush, indeed, belongs to a much more advanced stage of civilisation than the Comb, for whereas we find combs, however rude they may be, used in semi-savage, or rather, barbarian countries, the Brush is, as far as I know, an adjunct of a

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Combs.

Combs.

We will now proceed to the Comb , and see how Art has been anticipated by Nature. As long as human beings possess hair upon their heads, whether it be the short, frizzed, woolly pile of the negro, the thick, coarse crop of the Fijian, the coarse, straight hair of the Mongolian, or the long and fine hair of the Georgian races, they must, as soon as they attempt any kind of civilisation, form some instruments by which the hair can be dressed. The simplest machine for this purpose is the Comb, and

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Buttons, Hooks and Eyes, and Clasp.

Buttons, Hooks and Eyes, and Clasp.

Having now treated of brushes and combs as articles belonging to the toilet, we will proceed to those which belong to the dress rather than the person. It is a curious fact that, as far as is known, buttons and hooks belong only to advanced civilisation. The simplest garment is, of course, a cloth of some material wrapped round the waist, and, as we see in the wonderful Egyptian paintings which have survived their painters some three thousand years, the simple fold can retain its grasp round the

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The Stopper, or Cork.

The Stopper, or Cork.

T HIS object, as depicted in the illustration, is a product of civilised life, though, as soon as a savage could make a vessel, he seems to have made a Cover for it if it were of large diameter, or a Stopper if the opening were small. Even the very Bosjesman, who is quite unable to make a clay vessel, and uses empty ostrich eggs by way of water-bottles, is yet capable of making plugs with which he can stop up the apertures. Then the Kafir, with his gourd vessels, whether they be for water or snu

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The Filter.

The Filter.

Even in a state of uncivilisation man has been driven to invent a Filter of some kind. The simplest kind of Filter is that which is used by the Bosjesman women when procuring water for the use of their families. When, as often happens, the only water to be obtained is to be found in muddy pools which have been trampled and perturbed by thirsty animals, the women have recourse to a simple, though rather repulsive, expedient. Each woman is furnished with empty ostrich egg-shells by way of water-ve

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Elastic Springs.

Elastic Springs.

H ERE we come upon a subject so large, that it is difficult to define its exact requisite limits. The principle of the elastic spring pervades all Nature, and the numerous adaptations in Art are closely, though perhaps not directly, attributable to the wide distribution of the spring in Nature. There is, for example, the simple elasticity which enables a tree, when bowed by the wind, to spring back so soon as the pressure is removed, and which, indeed, is the power which enables a bow to propel

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The Spiral Spring.

The Spiral Spring.

This subject is so large, and there are so many examples, both in Art and Nature, that it is not very easy to make selections which will sufficiently answer the purpose. The upper left-hand figure of the illustration represents the ordinary Spiral Spring made of wire, and used for its power of resuming its shape when compressed. In early childhood most boys have had practical experience of this spring in the toy guns and cannons with which they are supplied. The spring is compressed by the ramro

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Spiral and Ringed Tissues.

Spiral and Ringed Tissues.

W E have now to consider the Spiral Tissue under another aspect, i.e. that of acting as the internal support of an exterior membrane. Ringed tissues are necessarily conjoined with the Spiral, as they both discharge the same office, and in some cases merge almost imperceptibly into each other in the same specimens. This is most beautifully shown in the proboscis of the common House-fly, to which reference will presently be made. The subject is so large that only a comparatively small selection of

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Diving and Divers.

Diving and Divers.

It has already been mentioned that the flexible tubes used by modern divers are constructed on the model of several structures belonging to the animal and vegetable kingdoms. We will now see how they are utilised. In the earlier stages of the diver’s art the Diving-bell afforded the only means of gaining access to the bed of the sea, even in comparatively shallow waters. The mode in which this result was obtained was simple enough, and though it carried with it the germs of still greater impro

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The Leaping Spring.

The Leaping Spring.

The last of the springs which can be mentioned in this work are those which are used for leaping purposes. The figure on the right hand represents the common Spring-jack or Skip-jack with which children are always so much amused. It consists of a flattened piece of wood called the “tongue,” which is inserted into a twisted string, so that it forms a tolerably powerful spring. When twisted round, and then suddenly released, it strikes against the ground with such force that the whole machine is t

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USEFUL ARTS. CHAPTER VII. FOOD AND COMFORT.

USEFUL ARTS. CHAPTER VII. FOOD AND COMFORT.

Parents and their Young.—Milk, and the various Ways of obtaining and using it.—The Kafir Tribes and Clotted Milk.—The Tonga Islanders.—The Tartars.—Ants and Aphides.—Honey-dew.—Milch Cows in Insect-land.—Fish-tanks and Aquaria.—Bill of the Pelican.—Eggs and Chickens.—The Hen-coop.—Nest of Termite.—Workers and Queen.—Egg-hatching.—The Hen and her Young.—Artificial Egg-hatching Machine.—The Snake and her Eggs.—The Gad-fly and Bot-fly.—Preservation of Provisions.—Hanging Meat.—Eggs of the Lace-wing

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USEFUL ARTS. CHAPTER VIII. DOMESTIC COMFORT.

USEFUL ARTS. CHAPTER VIII. DOMESTIC COMFORT.

How to make Home comfortable.—The Bed in its various Forms.—The Feather Bed of Man.—The Eider-duck and her Plumage.—The Rabbit and her Down.—The Long-tailed Titmouse and her wonderful Nest.—The Hammock of civilised Man and Savage.—The Sailor’s Canvas Hammock.—The String Hammock of tropical America.—Nest of the Pensile Oriole.—Silken Hammock of the Tiger-moth and other Insects.—The Mat Bed.—Cocoa-nut Matting.—The Robber-crab and its Bed.—Strength and Uses of the Cocoa-nut Fibre.—The Surgeon’s “Cr

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Artificial Warmth.

Artificial Warmth.

P ASSING from the direct to the indirect comforts of a household, we will take Artificial Warmth. The savage, as a matter of necessity, makes a fire in the middle of his hut, and lets the smoke have its own way. Sometimes, as is the case with the North American Indians, the top of the conical hut is open, and the whole edifice is a single chimney of large dimensions, something like the “chimney-corner” of past days, which only survives in such places as the New Forest. Then there are the various

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Ring and Staple.

Ring and Staple.

Humble , and apparently insignificant, as the principle of the Ring and Staple may be, we owe no small amount of our domestic comfort to it. It meets us in all kinds of ways, in the hinges of our boxes, in the padlocks of our doors, in the innside fastenings for our horses, in the seaside fastenings for ships’ cables, and in a thousand other ways too many to enumerate. On the right-hand side of the next illustration is shown the Ring and Staple as used for the purpose of mooring ships and boats,

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The Fan.

The Fan.

Except in permanently cold countries, a Fan of some kind seems to be an absolute necessity. Sometimes, as in the greater part of Europe, it is used only by the softer sex. The harder sex would often be only too glad to use it if they dared, and the same observation is equally true with regard to the parasol. But, in such lands as Japan and China, the Fan is an absolute necessity of existence. Men, women, and children alike carry their Fan, and almost perpetually use it. I remember, when the trou

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Burial.

Burial.

Last scene of all. I do not think that it matters very much to one who has “shuffled off this mortal coil” what becomes of the coil in which he had been imprisoned. Whether the abandoned body be buried in the earth, or sunk in the sea, or devoured by wild beasts, or consumed by fire, signifies nothing to him, though it may signify much to his surviving friends. As a rule, the animals, of whatever kind they may be, contrive to dispose of their mortal remains in some mysterious manner, so that not

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USEFUL ARTS. CHAPTER X. WATER, AND MEANS OF PROCURING IT.

USEFUL ARTS. CHAPTER X. WATER, AND MEANS OF PROCURING IT.

The Necessity of Water to Man.—Composition of the Human Body.—Natural and Artificial Distillation.—The Traveller’s Tree.—Pitcher-plants and Monkey-pots.—Stomach of the Camel, and its Analogy to the Honey-comb.—Dewdrops.—Use of the Still at Sea.—Perspiration and its cooling Properties.—The Turkish Bath.—Perfume and Ether Spray.—Condenser of the Low-pressure Steam-engine.—The Dry and Wet Bulb Thermometer.—Ice produced in a red-hot Vessel.—Power of Water.—How Fountains are made.—Modern System of Hy

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Aërostatics.

Aërostatics.

W E will begin this chapter with the only two modes at present known by which man can ascend from the earth or descend to it with safety, namely, the Balloon and the Parachute, the latter being generally attached to the former, and detachable at pleasure. The Balloon is, in fact, as its name imports, a large, hollow, air-tight ball, filled with some substance lighter than ordinary air. The original Balloons by Montgolfier were filled with heated air exactly like our toy fire-balloons. Just as th

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Weight of Air.

Weight of Air.

We have already noticed that hydrogen gas is fourteen times lighter than air, and infer necessarily that the weight of the atmosphere must be very considerable if so heavy an object as a balloon, with its car, instruments, sand-bags, and passengers, can rise and float in it. We are not conscious of its weight, because it permeates us, and the pressure is neutralised. But, in fact, we live at the bottom of a vast ocean which we call the atmosphere; and as, on an average, there is a pressure of fi

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Means and Appliances.

Means and Appliances.

I N this chapter we will take some miscellaneous appliances of force both in Art and Nature. In the accompanying illustration is shown the Cassava Press of Southern America, a most effective and simple instrument for extracting the juices of the root. These juices are poisonous when raw, but, when properly boiled and cooked, they make an excellent sauce. The press in question is an elastic tube made of flat strips of cane woven together exactly like the “Siamese Link,” which will be presently de

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Means and Appliances (continued).

Means and Appliances (continued).

W E will now treat rather more in detail the two subjects which were lightly touched upon at the end of the last chapter. The reader will remember that the diamond-headed borer is made in telescope form, so as to be adjustable at pleasure. It was also remarked that the ovipositor of the Gad-fly was made in a similar fashion, so as to be withdrawn within the body of the insect when not needed, and protrusible to a considerable extent when the Gad-fly wishes to deposit her eggs. As to our modern t

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Locomotion.—Direct Action.

Locomotion.—Direct Action.

The second point which has to be elucidated is that or progress by means of Direct Action. We have already seen how vessels can be propelled by sail, oar, paddle, or screw. We have now to consider a mode of progress which requires none of these things, but which works by means of Direct Action. Such, for example, is the progress of a Rocket through the air. The heated gases rush out with tremendous violence, and, by their pressure, urge the heavy rocket into the air with the rush, roar, and bang

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Distribution of Weight.

Distribution of Weight.

Being on the subject of locomotion, we will examine a few of the contrivances by which a man is enabled to pass in safety over soft substances into which he would otherwise sink. The first and best-known of these is the Snow-shoe of Northern America. It is a framework of wood, shaped as shown in the upper figure on the right-hand side, and strengthened by two cross-bars. The interior of the “shoe” is filled in with hide thongs arranged much like those of a racket, and stretched as tightly. The f

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Tree-climbing.

Tree-climbing.

Another curious aid to locomotion is shown in the accompanying illustration. In many parts of the world, where the cocoa-nut palm grows, the natives have invented a simple, but ingenious, plan for ascending the tall, curved stem. Such a thing as an upright palm-tree is unknown, and consequently the ascent of the branchless stem is not an easy task without artificial assistance. When I treated of Warfare and the different modes of scaling walls, the climbing-spur was casually mentioned. The imple

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The Wheel.

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-lan

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Art.

Art.

W E will now touch lightly on the subject of Art. In the present day one of the most indispensable accessories to art is Paper. It is a curious fact that we have no records as to the time when paper was first invented. The Egyptian papyrus we do not consider, as it was not paper in our sense of the word, although we have retained the name. Paper is a vegetable fibre carefully disintegrated, made into a pulp with water, and then dried in thin sheets. As is the case with many arts, China seems to

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Stippling.

Stippling.

We now come to another branch of Art, namely, the production of shadow in an engraving by means of Stippling, i.e. the insertion of dots instead of lines. At one time the Stipple was in great favour. Then it was almost wholly abandoned in favour of the line, and now it is much used in conjunction with the line, especially for the delicate shading of flesh tints, such as faces, female arms, &amp;c. In the illustration a little stippling of a cheek is shown, the dots being purposely exaggerate

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Plaster Casts.

Plaster Casts.

We have already mentioned the electrotype, and may now come to a branch of art which is much associated with it, namely, the Stereotype. As many of my readers may know, types are very valuable articles, and must not be wasted. If, therefore, a book should be thought likely to have a steady sale, much of its value would be lost if the types were kept standing, inasmuch as they could not be used for any other work. In such cases the Stereotype is employed. Omitting minute details, the process is a

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Corrugated Iron.

Corrugated Iron.

We have already seen that the Wasps are paper-makers. We may now see how some of the Wasps have anticipated a valuable invention of man, namely, the principle of corrugation, whereby a thin plate gains strength. Even a sheet of paper gains great strength by corrugation, as is seen in those paper covers which are so much in use for the decoration, or rather the concealment, of flower-pots. But the best example that can be given of this principle is the Corrugated Iron, which has come so much into

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Electricity and Magnetism.

Electricity and Magnetism.

I T has long been known that Electricity, Galvanism, and Magnetism are but different manifestations of the same force, and that one can be converted into the other at will. It is also known that this wonderful and most important principle lies latent in everything, and only needs the proper machinery to evoke it. The few following illustrations are intended to show its prevalence in Nature, and that human art does not create, but only makes manifest a power that exists, but lies latent until cal

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Magnetism.

Magnetism.

Now we come to another condition of electrical force, called Magnetism . One form of it is strongly developed in the Loadstone, an ore of iron. This ore has the property of turning east and west when suspended freely, it attracts any object made of iron, and can communicate its powers to iron by merely stroking it. There is in the Museum at Oxford a splendid specimen of the Loadstone, which has imparted its virtues to thousands of iron magnets, and has lost none of its virtues by so doing. All b

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The Spiral.

The Spiral.

In an early portion of this work the Spiral or Screw was touched upon, mostly in connection with the propulsion of vessels. We will now extend it a little further, and see how it is modified so as to perform other offices than those which have been described. Allusion has already been made to the Spiral or Wedge principle, but some of the illustrations were accidentally omitted. I therefore introduce them here, this being a chapter of miscellanea. The Windmill has previously been described, as h

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Centrifugal Force.

Centrifugal Force.

Closely connected with the spiral principle is Centrifugal Force, that marvellous power which gives to our whole solar system its ceaseless movements, and may extend, as far as we know, to other and vaster systems yet unknown. Tie a ball to a string, and swing it round, and it will be an exact, though rough, representation of the double power by which the movements of the heavenly bodies are governed, our earth being included among them. The string represents the force of attraction, which binds

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The Escapement.

The Escapement.

As we are on the subject of the pendulum and Escapement, we will say a few words about the latter piece of mechanism. It is here given on a larger scale than in the previous illustration, so that its action may be more easily understood. Whether in watch or clock, the Escapement is exactly the same in principle. First there is the escapement wheel, the circumference of which is furnished with a number of very deep cogs, varying as to the work which they have to do. Then there comes the escapemen

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Union is Strength.

Union is Strength.

ON the left hand of the accompanying illustration we have an example of the wonderful power obtained by uniting together a number of comparatively weak objects. It represents a portion of the rope attached to the harpoon with which the natives of some parts of Africa attack and kill the hippopotamus. Considering that a full-grown hippopotamus weighs several tons, and, in spite of its enormous size, is as active as a tiger, we can infer the strength of the rope which must be needed to hold such a

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Principle of the Dome.

Principle of the Dome.

We are all familiar with Domes, especially when the Dome of St. Paul’s is the most conspicuous object in our metropolis. Few persons, however, except professional architects and builders, seem to ask themselves the principle on which the Dome is constructed. The strength of the arch is well known, and the Dome is practically a number of arches, affording material support to each other, and so enormously increasing the strength of the edifice. A good idea of the Dome principle may be formed by ta

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The String and Reed.

The String and Reed.

It has previously been mentioned that all sounds are owing to vibrations of the air. But there are many ways of producing these vibrations, and each mode gives a different quality of tone. We have already seen, by means of the drum, how sound is produced by percussion. We shall now see how sounds can be produced by the vibrations of a String. If the string of a bow be pulled and smartly loosed, the result is a distinctly musical sound, higher or lower according to the length and tension of the s

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Acoustics as Aids to Surgery.

Acoustics as Aids to Surgery.

We have already seen how the air-vibrations poured in at the small end of the trumpet can make resonant notes. We have now to see how the reverse process can be employed, and sounds poured into the larger end be conveyed to the ear. The Ear-trumpet is a familiar example of such an instrument, and, as it is shown in the illustration, there is no need of further description. It is rather remarkable, by the way, that the length of tube does not seem to interfere with the conveyance of sound, as may

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Measurement of Sound.

Measurement of Sound.

Of late years we have had an instrument which enables us to measure the vibrations of sound as accurately as the barometer measures the weight of the atmosphere, the thermometer the temperature, and the photometer the power of light. This is the Siren, which is shown on the right hand of the accompanying illustration. To explain this instrument fully would require ten times the space which we have at command, and necessitate a great number of drawings. I will, therefore, endeavour to explain its

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Echo.

Echo.

Our last page will be given to the phenomenon called by the name of Echo , which consists in the power of solid substances, whether natural or artificial, of reflecting the waves of sound thrown against them, just as a mirror reflects the waves of light. Very often the Echo is naturally formed, as shown in the illustration, by rocks which cast back the sound—waves thrown against them. This is the case in several parts of Dovedale in Derbyshire, where a pistol shot is reverberated backwards and f

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