people and of one period, would require the constant and minute attention of many observing minds in local and general remarks on the state of the lower classes of society, and the causes that influenced it; and to draw accurate inferences upon this subject, a succession of such historians for some centuries would be necessary. This branch of statistical knowledge has of late years been attended to in some countries, and we may promise ourselves a clearer insight into the internal structure of human society from the progress of these inquiries. But the science may be said yet to be inits infancy, and many of the objects, on which it would be desirable to have information, have been either omitted or not stated with sufficient accuracy. Among these perhaps may be reckoned, the proportion of the number of adults to the number of marriages; the extent to which vicious customs have prevailed in consequence of the restraints upon matrimony; the comparative mortality among the children of the most distressed part of the community, and of those who live rather more at their ease; the variations in the real price of labour; the observable differences in the state of the lower classes of society with respect to ease and happiness, at different times during a certain period; and very accurate registers of births, deaths, and marriages, which are of the utmost importance in this subject.

"A faithful history, including such particulars, would tend great ly to elucidate the manner in which the constant check upon population acts; and would probably prove the existence of the retrograde and progressive movements that have been mentioned; though the times of their vibration must necessarily

be rendered irregular from the operation of many interrupting causes, such as the introduction of or failure of certain manufactures, a greater or less prevalent spirit of agricultural enterprise: years of plenty, or years of scarcity; wars, sickly seasons, poor laws, emigra tion, and other causes of a similar nature.

"A circumstance which has, perhaps, more than any other contributed to conceal this oscillation from common view is, the difference between the nominal and real price of labour. It very rarely happens that the nominal price of labour universally falls; but we well know that it frequently remains the same, while the nominal price of provisions has been gradually rising. This is, in effect, a real fall in the price of labour; and, during this period, the condition of the lower classes of the community must be gradually growing worse. But the farmers and capitalists are growing rich from the real cheapness of labour. Their increasing capitals enable them to employ a greater number of men; and, as the population had probably suffered some check from the greater difficulty of supporting a family, the demand for labour, after a certain period, would be great in proportion to the supply, and its price would of course rise, if left to find its natural level; and thus the wages of labour, and consequently the condition of the lower classes of society, might have progressive and retrograde movements, though the price of labour might never nominally fall.

"In savage life, where there is no regular price of labour, it is little to be doubted that similar oscillations take place. When population has increased nearly to the utmost

limits of the food, all the preventive and the positive checks will naturally operate with increased force. Vicious habits with respect to the sex will be more general, the exposing of children more frequent, and both the probability, and fatality, of wars and epidemics, will be considerably greater; and these causes will probably continue their operation till the population is sunk below the level of the food; and then the return to comparative plenty, will again produce an increase, and after a certain period, its further progress will again be checked by the same causes.

"But without attempting to establish in all cases these progressive and retrograde movements in different countries, which would evidently require more minute histories than we possess, the follow

ing propositions are proposed to be proved:

1. Population is necessarily limited by the means of subsistence. "2. Population invariably increases, where the means of subsistence increase, unless prevented by some very powerful and obvious checks.

"3. These checks, and the checks which repress the superior power of population, and keep its effects on a level with the means of subsistence, are all resolvable into moral restraint, vice, and misery.

"The first of these propositions scarcely needs illustration. The second and third will be sufficiently established by a review of the past and present state of society.

"This review will be the subject of the following chapters."

blown bladders below their arms. But these methods are attended with inconveniences, which may be remedied in the following manner.

"Between the cloth and lining of a jacket, without arms, place small pieces of cork, an inch and a half square, and about half or three quarters of an inch in thickness. They must be arranged very near to each other, that as little space as possible may be lost; but yet not so close as to affect, in any degree, the flexibility of the jacket, which must be quilted to prevent their moving from their places. The jacket must be made to button round the body, by means of strong buttons, well

N 3

sewed

sewed on; and to prevent its slipping off, it ought to be furnished behind with a kind of girdle, so as to pass between the thighs and fasten before.

"By means of such a jacket, which will occasion as little embarrassment as a common dress, people may throw themselves into the water with the greatest safety; for if it be properly made the water will not rise over their shoulders. They will sink so little, that even a dead body in that situation would infallibly float. The wearers therefore need make no effort to support themselves; and while in the water they may read or write, and even load a pistol and fire it. In the year 1767 an experiment was made of all these things by the abbé de la Chapelle, fellow of the Toyal society of London, by whom this jacket was invented.

"It is almost needless to observe how useful this invention might be on land as well as at sea. A sufficient number of soldiers, provided with these jackets, might pass a deep and rapid river in the night time, armed with pistols and sabres, and surprise a corps of the enemy. If repulsed, they could throw themselves into the water, and escape without any fear of being pursued.

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During sea voyages, the sailors, while employed in dangerous manœuvres, often fall overboard and are lost; others perish in ports and harbours by boats oversetting in consequence of a heavy swell, or some other accident; in short, some vessel or other is daily wrecked on the coasts, and it is not with out difficulty that only a part of the crew are saved. If every man, who trusts himself to this perfidious element, were furnished with such a cork jacket, to put on during the

moments of danger, it is evident that many of them might escape death."

To construct a Boat which cannot be sunk, even if the Water should enter it on all Sides.

"Cause a boat to be made with a false bottom, placed at such a distance from the real one, as may be proportioned to the length of the boat, and to its burthen and the number of persons it is intended to carry. According to the most accurate calculation, this distance, in our opinion, ought to be one foot, for a boat eighteen feet in length, and five or six in breadth. The vacuity between this false bottom and the real one ought to be filled up with pieces of cork, placed as near to each other as possible: and as the false bottom will lessen the sides of the boat, they may be raised proportionally; leaving large apertures, that the water thrown into the vessel may be able to run off. It may be proper also to make the stern higher, and to furnish it with a deck, that the people may take shelter under it, in case the boat should be thrown on its side by the violence of the waves.

"Boats constructed in this manner might be of great utility for going on board a vessel lying in a harbour, perhaps several miles from the shore; or for going on shore from a ship anchored at a distance from the land. Unfortunate accidents too often happen on such occasions, when there is a heavy surf, or in consequence of some sudden gust of wind; and it even appears that sometimes the greatest danger of a voyage is to be apprehended under circumstances of this kind. But boats constructed on the above principle would prevent such accidents.

"Much

"Much we confess is to be added to this idea, presented here in all its simplicity; for some changes perhaps ought to be made in the form of the vessel; or heavy bodies ought to be added in certain places to increase its stability. This is a subject of research well worth attention, as the result of it might be the preservation of thousands of lives every year.

"For this invention we are indebted to M. de Bernieres, one of the four controllers-general of bridges and causeways; who, in 1769, constructed a boat of this kind for the king. He afterwards constructed another with improvements for the duke de Chartres; and a third for the marquis de Marigny. The latter was tried by filling it with water, or endeavouring to make it overset; but it righted as soon as left to itself; and though filled with water, was still able to carry six persons.

"By this invention the number of accidents which befal those who lead a sea-faring life, may in future be diminished; but the indifference with which the invention of M. de Bernieres was received, shews how regardless men are of the most useful discoveries, when the general interests of humanity only are concerned, and when trouble and expence are required to render them practically useful."

How to raise from the Bottom of the Sea a Vessel which has sunk.

"This difficult enterprise has been several times accomplished by means of a very simple hydrostatical principle, viz. that if a boat be loaded as much as possible, and then unloaded, it tends to raise itself with a force equal to that of the weight of the volume of water

which it displaced when loaded. And hence we are furnished with the means of employing very powerful forces to raise a vessel that has been sunk.

"The number of boats employed for this purpose, must be estimated according to the size of the vessel, and by considering that the vessel weighs in water no more than the excess of its weight over an equal volume of that fluid; unless the vessel is firmly bedded in the mud; for then she must be accounted of her full weight. The boats being arranged in two rows, one on each side of the sunk vessel, the ends of cables, by means of divers, must be made fast to different parts of the vessel, so that there shall be four on each side for each boat. The ends of these cables which remain above water, are to be fastened to the head and stern of the boat for which they are intended. Thus, if there are four boats on each side, there must be thirty-two cables, being four for each boat.

"When every thing is thus arranged, the boats are to be loaded as much as they will bear without sinking, and the cables must be stretched as much as possible. The boats are then to be unloaded, two and two, and if they raise the vessel, it is a sign that there is a sufficient number of them; but, in raising the vessel, the cables affixed to the boats which remain loaded will become slack, and for this reason they must be again stretched as much as possible. The rest of the boats are then to be unloaded, by shifting their lading into the former. The vessel will thus be mised a little more, and the cables of the loaded boats will become slack; these cables being again stretched, the lading of the latter boats must be shifted back into the others, which N4

will

will raise the vessel still a little higher; and if this operation be repeated as long as necessary, she may be brought to the surface of the water, and conveyed into port, or into dock.

"An account of the manoeuvres employed to raise, in this manner, the Tojo, a Spanish ship belonging to the Indian fleet, sunk in the har. bour of Vigo, during the battle on the 10th of October 1702, may be seen in the Mémoirs des Academiciens étrangers,' vol. ii. But as this vessel had remained more than thirty-six years in that state, it was imbedded in a bank of tenacious clay, so that it required incredible labour to detach it; and when brought to be surface of the water, it contained none of the valuable articles expected. It had been one of those unloaded by the Spaniards themselves, before they were sunk, to prevent them from falling into the hands of the English.

"On the same principle is constructed the camel, a machine employed by the Dutch for carrying vessels heavily laden over the sand banks in the Zuyder-Zee. In that sea, opposite to the mouth of the river Ý, about six miles from the city of Amsterdam, there are two sand banks, between which is a pas sage, called the Pampus, sufficiently deep for small vessels, but not for those which are large and heavily laden. On this account ships which are outward bound take in before the city only a small part of their cargo, receiving the rest when they have got through the Pampus; and those that are homeward bound must, in a great measure, unload before they enter it. For this reason the goods are put into lighters, and in these transported to the warehouses of the merchants in the city; and the

large vessels are then made fast to boats, by means of ropes, and in that manner towed through the passage to their stations.

"Though measures were adopted, so early as the middle of the sixteenth century, by forbidding ballast to be thrown into the Pampus, to prevent the farther accumu lation of sand in this passage, that inconvenience increased so much, from other causes, as to occasion still greater obstruction to trade; and it at length became impossible for ships of war and others heavily laden to get through it. About the year 1672, no other remedy was known, than that of making fast to the bottoms of ships large chests filled with water, which was afterwards pumped out, so that the ships were buoyed up and rendered sufficiently light to pass the shallow. By this method, which was attended with the utmost difficulty, the Dutch carried out their nume. rous fleet to sea in the above-mentioned year. This plan however gave rise soon after to the inven tion of the camel, by which the labour was rendered easier. The camel consists of two half ships, constructed in such a manner that they can be applied, below water, on each side of the hull of a large vessel. On the deck of each part of the camel are a great many horizontal windlasses; from which ropes proceed through apertures in the one half, and, being carried under the keel of the vessel, enter similar apertures in the other, from which they are conveyed to the windlasses on its deck. When they are to be used, as much water as may be necessary is suffered to run into them; all the ropes are cast loose, the vessel is conducted be tween them, and large beams are placed horizontally through the

port