MECHANICAL APPLIANCES.
To Raise and Move a Heavy Body.--On Land.--Lever up its ends alternately, and build underneath them when they are lifted up. After a sufficient height has been gained, build a sloping causeway down to the place to which the mass has to be moved, and along which it may be dragged, with the assistance of rollers and grease. If the mass be too awkwardly shaped to admit of this, burrow below it; pass poles underneath it, and raise the ends of the poles alternately. Mr. Williams, the well-known missionary of the South Sea Islands, relates how his schooner of from seventy to eighty tons had been driven by a violent hurricane and rising of the sea, on one of the islands near which she was anchored, and was lodged several hundred yards inland; and thus describes how he got her back:--"The method by which we contrived to raise the vessel was exceedingly simple, and by it we were enabled to accomplish the task with great ease. Long levers were passed under her keel, with the fulcrum so fixed as to give them an elevation of about forty-five degrees. The ends of these were then fastened together with several cross-beams, upon which a quantity of stones were placed; the weight of which gradually elevated one end of the vessel, until the levers reached the ground. Propping up the bow thus raised, we shifted our levers to the stern, which was in like manner elevated; and, by repeating this process three or four times, we lifted her in one day entirely out of the hole (which she had worked for herself, and which was about four feet deep). The bog that lay between her and the sea was then filled up with stones, logs of wood were laid across it, rollers were placed under the vessel, the chain cable passed round her; and, by the united strength of about 2000 people, she was compelled to take a short voyage upon the land, before she floated in her pride on the sea."
In some cases, the body of a cart may be taken down, and deep ruts having been dug on each side of the mass, the vehicle can be backed, till the axletree comes across it; then, after lashing and making fast, the sand can be shovelled from below the mass, which will hang suspended from the axletree, and may be carted away. Or a sledge may be built beneath the mass by burrowing below it and thrusting the poles beneath it. Then the remainder of the intervening sand can be shovelled away, and the mass, now resting directly upon the sledge, can be dragged away by a team of cattle.
A sarcophagus of immense weight was raised from out of a deep recess into which it had been fitted pretty closely, at the end of a long narrow gallery in an Egyptian tomb, where there was no room for the application of tackle or other machinery, by the simple expedient of slightly disturbing it in its place and sifting sand into the narrow interval between its sides and the recess. This process was repeated continually: the sand settled below the bottom of the sarcophagus, which gradually rose out of the hole in which it had lain. The principle of this piece of engineering was borrowed, I suppose, from observing that whenever a mass of sand and stones is shaken together, the stones invariably rise out of the sand, the biggest of them always forming the highest layer.
Expansive Power of Wetted Seeds.--Admiral Sir E. Belcher read a curious paper before the British Association in 1866, showing the remarkable power to be obtained by filling tubes with peas or other seed, allowing the weight to rest upon the surface of the peas through the medium of a rude piston. When the peas were wetted they swelled upwards with considerable force. A pint of peas placed in a tube of a diameter that was not expressed in the newspaper report, from which I take this account, lifted 60 lbs. through a height of one inch in twenty-four hours. The Admiral proposed to fix a number of tubes side by side in a frame below the mass to be lifted, preferring to use zinc tubes of from two or three inches in diameter, and of about one foot high. Thus, in the small space of a cubic foot, a large number of tubes (thirty-six in the one case, sixteen in the other) could be made to act simultaneously; the force of the stroke could be increased by arranging a number of frames side by side, or the length of the stroke could be increased by building the frames in a series one above the other. I have elsewhere described how wetted seeds may be used to restore the shape of a battered flask either for holding water or gunpowder (pp. 230).
Parbuckling.--A round log or a barrel should be rolled, not dragged; and many irregularly-shaped objects may have bundles of faggots lashed round them, by which they become barrel-shaped and fit to be rolled. In these cases, parbuckling doubles the ease of rolling them; one or more ropes have one of each of their ends made fast in the direction to which the log has to be rolled, while the other is carried underneath the log, round it, and back again. By pulling at these free ends, the log will be rolled on. An equivalent plan, and in some cases a more practicable one, is to make fast one end of the rope to the log itself; then, winding the rope two or three times round it, like cotton on a reel, to haul at the free end as before. Horses can be used, as well as men, for this work.
Accumulation of Efforts.--South American Indians are said to avail themselves of their forest trees, and of the creepers which stretch from branch to branch, in moving very heavy weights, as in lifting a log of timber up on a stage to be sawn, in the following ingenious manner. The labourer gets hold of one of these creepers that runs from the top boughs of a tree in the direction in which he wants to move his log, and pulling this creeper home with all his force, bending down the bough, he attaches it to the log; then he goes to another creeper and does the same with that; and so on until he has accumulated strain of many bent boughs, urging the log forward and of sufficient power to move it.
Short cords of india-rubber with a hook at either end, are sold under the name of "accumulators." It is proposed that each of these should be stretched and hooked by one of its ends to a fixed ring, and by the other, to the body to be moved; by applying a number of these, in succession, an immense accumulation of force can be obtained.
Levers.--A piece of green wood has insufficient strength to be used as a crowbar; it must first be seasoned. (See "Green Wood, to season.")
Other Means of Raising Weights.--I do not propose to take space by describing jacks, ordinary pulleys, differential pulleys, Chinese windlasses, and the like. It is sufficient that I should recall them by name to the traveller's recollection; for if he has access to any of these things he is probably either a sailor or engineer and knows all about them, or he is in a land where mechanical appliances are understood.
To raise Weights out of Water.--If the mass should lie below water, a boat may be brought over it and sunk to its gunwales; then, after making fast to it, the boat can be baled and the thing floated away. A raft weighted with stones will serve the same purpose. In some cases a raft may be built round the mass during low water; then the returning tide or the next flush of the stream will float it away.
"Although from its bulk several men might be puzzled to lift a cow-fish from the water when dead, yet one single Indian will stow the largest in his montaria without assistance. The boat is sunk under the body, and rising, the difficult feat is accomplished." (Edwards' 'Amazon.')
The huge blocks of marble quarried at Carrara are shipped in the small vessels of the country, as follows:--at low water the vessel is buried bodily in the sand, and a temporary railway laid down from the quarry to withinside of it. Along this the blocks are conveyed, and, when deposited in the vessel, the sand is dug away from under them, and they settle down in its hold, and the ship floats away at the returning tide.