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 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 fresh waters 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, to give 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.
We now 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.
Long before 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.
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 gluten
Et 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 bees under 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.
TOOLS.
CHAPTER I.
THE DIGGING-STICK.—SPADE.—SHEARS AND SCISSORS.—CHISEL AND ADZE.—THE PLANE AND SPOKESHAVE.
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 may sometimes 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.