mechanical

enterprises required a greater hand-power than that of a single man. The inference suggested by a study of the human remains of the glacial drift is that, from the very first, men turned themselves into a sort of compound machine by pulling together. Two facts conspired to impart to this act a peculiar development. The innate distaste of men to use their own hands on the one side, and the need for disposing of prisoners taken in war on the other, would, in an age of physical struggle, when one race could hope to exist only by effacing another, lead conquering tribes to utilize the accumulated energy of living captive men. In this sense it may be said that the first machine ever invented was a slavegang, and the first engineer its task

master.

thought to be later in point of time, there is no class more frequent than that of mortars and pestles. Sandstone blocks, or querns, bearing hollows which have about them the aspect of having been formed by the pounding of corn upon them, have been often found, and the whole inference is supported by other considerations that during the age of Stone the waterwheel as an agent for grinding corn was not yet invented. The utilization of human energy involved in the grinding of corn by hand was in fact replaced by that of quadrupeds long before horse and bullock power gave way to water-power. Cattle-mills, for instance, were in use amongst the Romans at an early date. It is difficult to suppose that the first inventors of the water-wheel used it for any purpose But besides the energy obtained from other than grinding, and the inference men, early engineers were not slow to is that mills driven by this power were utilize the power stored up in other of relatively late origin. There is reaanimals. There is evidence that even son to believe that the Egyptians had in the paleolithic age the art of domes-water-wheels in use in very early times; ticating animals was already in vogue; and one is known to have been erected and one of the earliest scratched bones extant the remote precursor of all pictorial art represents a man in the act of guiding a rude lopped pole, drawn by a horse, as a sort of primitive plough. The fact that in the Danish "kitchen-middens," or rubbish-heaps, all the marrow bones are found to be split and gnawed, is regarded as proof of the existence at that time of a breed of domestic dogs. The ass, also, as far back as Semitic traditions go, was a beast of burden in western Asia. When it is remembered that the ass is regarded as capable of five times the work that can be done by a man, and that the horse is ten times as powerful as a man, it will at once be perceived that the adoption of these animals as prime movers would add immensely to the mechanical capabilities of early engineers.

on the Tiber in the century before Christ. The first water-mill known in history is that described in connection with the Mithridatic wars. The tidewheel is of quite recent origin, none being recorded earlier than those used by the Venetians in 1078 A.D.

Windmills, also, were not known in Europe before the twelfth century, but are believed to have been in use in the East before this time. A sawmill is recorded to have been in use in Augsburg in 1332. The fact that of all modern African races not one has ever hit upon either water-power or wind-power seems to prove that they involve a knowledge of advanced kinematics not attained by any races out of the track of the early civilizations.

Although the property of rubbed amber was perceived by Thales as early as the seventh century before Christ, yet it need scarcely be said that heat and electricity, as practical prime movers, are developments of the past two hundred years.

The precise relative date at which water-power first came into use cannot be asserted. Amongst the remains of the Stone Age, from the earliest to those which, from their superior fin- Let us now examine one by one, in ish and more perfect adaptation, are the order of their birth, the mechanical

powers which are described as the sim- the fact that stone implements would ple machines. Here it may be ob- have been incompetent to fashion a served that whereas some of the lower wheel. The earliest Chaldean monuanimals do possess a knowledge of in- ments bear sculptured representations dividual powers, yet, if those particular of rude wooden carts with two fixed powers fail, they are incapable of car- wheels drawn by a single ox; but these rying out their desires by other means. very sculptures themselves prove that Monkeys, for instance, fetch them- metallic tools were in use at the time. selves cocoanuts and break them open at the same time by running up the palm-trunks and dropping the nuts to the ground. But if a nut should fall intact, the monkey would not have the cleverness to pick up a stone and break it; nor has it the aptitude to throw a stone upwards, and so bring the nut to the ground. Both these actions would imply the pre-requisite of an opposable thumb. Similarly, a beaver will drag a tree-trunk to the riverside, that it may be built into the beaver-dam; but if the trunk be too heavy, it will not have the power to put one trunk on another, and so roll the trunk along.

The lever must be quite as old as the roller. When several felled poles lay together helter-skelter, one of them would most likely have one of its ends resting under another, and accidental depression of the free end would reveal the fact that heavy weights might be moved by pushing under them one end of a pole, and pushing under the pole another by way of fulcrum. The transport of heavy weights, therefore, might take place quite naturally amongst the men who preceded the metallic age by the use of poles as levers and rollers. At that stage nothing in the way of a crank or axle would have been known. The lever, like other powers, was of course known long before its properties had been investigated by the mathematician. It was, in fact, not until the time of Archimedes that the lever was explained.

It may be useful here to point out that in the pre-metallic age, before nails were possible, fastenings were effected by means of knots. The older stone implements are distinguished from those of the newer age by having been lashed to a wood-shaft with leather thongs; whereas, later on, men found out how much better it was to make a hole, either in the stone head or in the wooden handle. The fact that stone implements are found scattered singly here and there seems to suggest that they had slipped by accident out of the shafts through unskilful tying; and from this we may infer that the grannyre-knots and other unscientific methods of tying which children instinctively adopt are a relic of the Stone Age fastenings.

It is in this capacity for inventiveness that the divergence of human aptitude from that of animals is to be found. Thus, there is no record of any brute creature ever deliberately and of set purpose transporting a weight from one point to another by rolling it down a hill. Yet the savage race does not exist which is incapable of this simple exercise of the inventive mind. Again, there is no record of a savage who would not be smart enough to drag one trunk over a smaller one, and so lessen the friction of transport. It may be taken for granted that the roller, in the form of a pole from which lateral branches had been lopped by cutting, breaking, or fire, was one of the earliest mechanical inventions. It would not be long before men perceived that by reducing the bulk of the trunk in the middle, the power of the roller was increased, because friction was duced, and in this way the middle part of the roller would at length develop into the axle, and its two ends into wheels. There is no evidence that trollies or carts of this rough pattern existed amongst the men of the Stone Age, and the theory that they had not yet been invented is strengthened by

From the position in which their remains are found, it may be said that the Stone Age races of western Europe obtained their supplies of fresh water from running streams and lakes. They would therefore have no knowledge of

artificial wells, which seem to have been hit upon by Syrian nomads in very early times. At first, perhaps, vessels would be lowered by a thong, and then pulled up again; but if a pole were placed across the well-mouth for purposes of safety, men would at once see the advantage of pulling the rope against the pole. Later on, they would acquire the means of fixing the pole in the holes of vertical boards, and so the pulley would arise. Even before this invention, it is probable that men hit upon the plan, when dragging a heavy weight by means of a leather thong, of passing the thong round a handy tree.

From The Athenæum.

LINES BY TOM SHERIDAN. SHERIDAN'S elder son Tom said many clever things, but he did not strive to make his mark in literature. Some letters from him are preserved among the Sheridan papers at Frampton Court, Dorsetshire, and several verses, which may be read with special interest now, are appended to one of them. They were written towards the end of 1811 or at the beginning of 1812. The subject was the total wreck of a man-of-war, about which the following particulars appeared in the "Annual Register" for 1811 :

The precise manner in which the Rathmilton, December 6th; his Majwedge was invented cannot be shown. esty's ship Saldanha, one of our finest Perhaps some archaic workman, ham- frigates, commanded by Captain the Hon. mering away at a block of wood with a W. Pakenham, brother to the Earl of Longflint knife, found the knife enter the ford, sailed from Cork on the 19th of wood and become fixed. In the effort November, to relieve his Majesty's ship to wrench it out, the block would split. Endymion off Lough Swilly. Having While the engineer of to-day is a reached the harbor, she again sailed on the being of a very different stamp from 30th, with the intention of proceeding to the engineer of the long-ago, the differ- the westward. On the evening of the 4th ence is one of degree rather than kind. of December it blew the most dreadful hurricane. At about ten o'clock at night, Modern mechanical activity has shown through the darkness and the storm, a itself not in the invention of new ma- light was seen from the signal-towers, supchines so much as in the application of posed to be on board the Saldanha, passing new prime movers. The tendency of rapidly up the harbor. When the daylight the time is to replace the prime movers appeared the ship was discovered to be a of the early ages by others involving complete wreck in Ballyna Stokes-bay. less human waste. The classic trireme Every one of the three hundred souls on was to all intents and purposes a ship, board had perished, and all the circumpropelled by a compound engine, whose stances of her calamitous loss had thus cranks were human elbows, and whose perished with her, The bodies of Capt. Pakenham and about two hundred of the pistons were human arms. A rower would not miss his stroke more fre- and were interred in a neighboring burying crew are said to have been washed ashore, quently than the needle of a sewing-ground.

machine misses a stitch. But the comparative costliness of men as prime movers has been amply demonstrated by the calculation that, to do the same number of units of work as that produced by the motor of a Cunarder no fewer than a quarter of a million rowers would be required.

But enough has been said to show that, before the age of iron, men had made considerable progress in mechanical invention, and it needed only the introduction of that metal to enable them to carry out the principles already known to gigantic issues.

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