judiced mind. It would occupy too much time to enter into the investigation of the various causes of this difference in the characters of the working classes; but I cannot pass by what appears to me to be the great leading cause; namely, that in country situations, the old and natural connexion betwixt master and servant is still maintained unimpaired, the latter continuing to look up to the former as his natural protector and guardian, while the former experiences from the latter, not only gratitude, but that deference to his wishes and opinions, which is the true soul-connecting link in society. Whereas, in populous and crowded towns, there is such a perpetual change of hands, that this tie is not only entirely broken; but too often the operatives look upon their employers as tyrants, whose only object is to reduce the working classes to the state of passive slaves, subservient only to the selfish views of their masters."

Such being Mr. Thom's views, it naturally occurred to him, that if any practicable means could be devised for transferring manufacturing establishments from crowded towns, where such deterioration of character took place, to pleasant and healthy situations in the country, a great national advantage would be obtained. Among other considerations, it could not fail to strike him, that a plan which would have the effect of rendering water power more generally applicable to such establish ments, would, by superseding the expensive use of steam power, be an important step towards this desideratum. Accordingly, his practical and experimental knowledge, joined to the advances he had now made in the theory of bydraulics, produced in his mind the germ of that system of water power, which he has lately so beautifully exemplified and com. pletely perfected in the works at Greenock. It was not, however, till 1815, that he had an opportunity of carrying his system practically into effect, by its application to Rothesay Cotton Mills. Prior to this period, these mills had been im

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pelled, partly by water, and partly by steam. The steam power consisted of two engines, one of twenty, and one of ten horse power; the water power being barely equal to half of the work required. Owing to local causes, the expense of steam power at Rothesay was considerably greater than at Glasgow and other manufacturing towns in the vicinity. On this account, water power at a moderate expense appeared to be essential to the very existence of Rothesay Mills. Every exertion was therefore made to obtain this desideratum, and the result of these exertions was the invention and adoption of that system which we now proceed to describe,—a system, which not only accomplished all that could be wished, but equalled the most sanguine expectations of the inventor.

General Description of the System.

To obtain a sufficient and regular supply for the mills, the whole year round, it was obviously necessary to enlarge the reservoir, and to fill it with water from additional resources to those which had hitherto proved inadequate. If the water produced after periodical and occasional rains, by the swelling of the streams which naturally run into the reservoir, be not enough to furnish the requisite daily supply at all seasons of the year, art must be employed to bring that supply from other sources at a greater or a less distance. How to accomplish this object was the first difficulty; how to accomplish it with the greatest safety and least expense, was the second. In mountainous or hilly grounds, it is evident that vast quantities of water, which might be rendered useful for this purpose, if it could be collected, must flow downwards in every direction to the sea; and that, unless it be intercepted in its passage thither, and treasured up for the use of man, its mechanical power must be entirely lost as soon as it reaches that level. In fact, it is only from that portion of such grounds which is contiguous to the banks of a reservoir, or in which the streams that

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run into it originate, that any supply in rainy seasons can be obtained; while from all the other portions of hilly districts, the water must run to waste, in so far as regards such a reservoir. It is at this point, therefore, that the inventor of the system comes to exert his ingenuity. He looks around from the top of some eminence, which commands a view of the country; he sees water more than enough to supply all his wants, flowing in abundance, in almost every direction but that in which it can be of use to him; and he observes reservoirs formed, and plentifully filled by nature, while his own affords but an occasional and a scanty supply. Nature appears to him to be bountiful indeed, if he could but avail himself of her bounty. To engage her, therefore, to render him her services, is his object. He easily perceives that every drop of water that flows from a spot higher than the level of bis reservoir should be made subservient to his purposes; he accordingly proceeds to consider and to adopt those schemes by which he may accomplish this desirable end. The plan adopted by Mr. Thom was perfectly natural, and simple in theory; but without an intimate acquaintance with the laws of fluids, and a facility in the invention of mechanical contrivances, it must have appeared, or at least have been found, on trial, very difficult and expensive in the execution. Fortunately, combining both qualities in an eminent degree, he has rendered the system as simple and easy in practice as it is natural and beautiful in theory.

Aqueducts commencing at the surface level of the reservoir, were carried nearly on that level (say, rising above it about a foot in 1200) in all possible directions round the bases of the hills or rising grounds in the vicinity, so as to intercept and carry to the reservoir all the streams and surface-water that used to flow from them into the sea in different directions. The embankments of the reservoir, at two different places, were raised, to render them capable

of containing this additional water; and auxiliary reservoirs were formed at various places, where the nature of the ground would easily admit of it, to serve as stores for the surplus water which could not be retained in the principal reservoir, without extending its capacity beyond convenient bounds. In addition to all this, however, it was obviously necessary to invent some plan by which the water in these reservoirs could be made to regulate itself; otherwise the danger attending the whole system would have been extreme, and the expense of its management very great. The aptitude of water, under pressure, during floods, to break through or push away embankments; the danger of wastewears being choked up by ice and other floating substances; the hazard of neglect in watching sluices, and opening them when occasion required; with many other circumstances in the conducting of water on such an extended scale;-must have rendered the system almost impracticable, unless some self-regulating scheme could be adopted, which would remove every difficulty, and bring the whole completely under his own control. The various self-acting sluices, described in the first article, were the means by which Mr. Thom was enabled to put the system into safe and active operation, and to render it completely independent of human management.

By such means, the water power of Rothesay Mills was more than doubled, and the proprietors were enabled to lay aside their steamengines entirely, thereby saving an expenditure which had rendered their works hitherto so unprofitable. The water power at these mills is now fully equal to that of a Bolton and Watt steam-engine of seventyhorse power. The expense of cutting the aqueducts, forming new reservoirs, enlarging the old ones, &c.'; in a word, the outlay for the whole of the operations, was about £3000. This expense will appear small, when the lengths of the aqueducts, the extent of the embankments for

reservoirs, and other necessary ope rations, are considered; all of which will be understood by a reference to the plan of these operations, to be given in a future Number. It must, however, be observed that, by the adoption of the various self-acting sluices, the water is brought to the principal reservoir in comparatively narrow aqueducts, the weathersluices, placed on the auxiliary reservoirs, retaining the water there during floods; so that, on such occasions, the aqueducts conduct only a part of the surface-water; and when the floods subside, those sluices open, and allow the remainder of this water gradually to follow. In this way, aqueducts, of only one half the size that would be otherwise required, serve for every necessary purpose, and thereby save, in their construction, nearly a half of the expense which would otherwise have been incurred.

There is another feature in this system, which is of very considerable importance, as it constitutes a great saving, both of labour and expense, in conducting works of this kind. We refer to the plan which Mr. Thom uniformly adopts, of carrying these aqueducts in a circuitous manner over chasms, ravines, and hollows of every description, instead of throwing them right across, as in the usual way, by aqueduct bridges. Many engineers, upon viewing the line of an aqueduct, and finding it intersected in various places by enormous chasms, precipitous ravines, and deep hollows, would pronounce it impossible to be cut, with out the erection of so many bridges across such places, as would render the undertaking not only expensive, but hazardous in the extreme. Mr. Thom's plan is quite the reverse of all this; it is simply to follow the line which nature points out, to carry the aqueduct equally along the side of the most gentle and easy declivity, and the face of the most precipitous and rocky precipice; to bring it in contact, not only with the calm and placid rills that it may meet in its passage, so as to increase its waters, but also with the roaring mountain torrent, and the lofty and

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foaming cataract; in a word, to yield simply to the guidance of the horizontal level, wherever it may take its winding and varied course. In cutting aqueducts along the face of an overhanging rock, or a hard and strong soil of any kind, the expense is considerably lessened, by making their width less, and their declivity greater, in such places; and a great saving is effected in the expense of the embankments, which may be more or less necessary in conducting them, by the adoption of the waster-sluices about to be described. These sluices, by preventing the rise of the water above an assigned height, either in aqueducts or reservoirs, renders it unnecessary to raise embankments so high, by several feet, as would otherwise brave been absolutely requisite, to prevent their destruction by overflowing, during floods. By the adoption of the waster-sluices, a considerable quantity of land is, also, preserved from inundation, which would otherwise be subject to this calamity on such occasions. The object and effect of all the other sluices, which form a part of Mr. Thom's system, and, in our opinion, not the least important part, is to economize in conducting such water-works on a great or a small scale, both by saving water, and the expense of water-men to look after the sluices, as will be fully and clearly understood by the description of these sluices contained in the first article.

The chief and the distinguishing feature in this system of water power is, therefore, the application of the various self-acting sluices to every possible exigency which can occur in the formation of extensive aqueducts and reservoirs; by which means we are enabled to convey water from the most remote and inaccessible places, to situations better adapted for the sites of mills, factories, villas, &c. This plan, moreover, gives to water power a greatly increased value, when compared with the ancient practice of erecting mills or factories only on such waterfalls as had been formed by nature. These waterfalls generally occur in distant and inconvenient situations for the

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purposes of trade, where neither houses, villages, nor roads, are to be found, and where, consequently, they have to be formed at a prodigious expense, in order to meet the wishes of proprietors, by rendering such mill sites useful. The perpetual expense incurred by the distance of works planted in such situations from markets of every kind, is another attendant upon their locality, of a description not less disadvantageous than any that have been mentioned.

(To be continued.)

OBJECTIONS TO THE COPERNICAN

SYSTEM REFUTED.

Sir,-Having read "J. B. C.'s" objections to the Copernican System ("Mechanics' Magazine," vol. xi. p. 265), I have to observe, that he has taken for granted that the centrifugal force at the equator is equal to gravity, or the centripetal force at the pole, and of course equal to the gravity at the equator (the earth being considered a perfect sphere), otherwise he could not conceive that these two forces mutually destroyed each other, in changing place from the equator to the pole, and vice versa.

In the above case, the two forces being equal, and in opposite directions, a body placed on the surface of the earth, at the equator, would

be void of weight, and float in the atmosphere, or even in vacuo, without any tendency either to rise or fall.

Now, the centrifugal force at the equator is found to be about 1-289th part of gravity; and this being the only loss which can be sustained by the centrifugal force, in changing place from the equator to the pole, will be, therefore, the only addition made to gravity by that change.

of which, "J. B. C." has made it as 1528 to 1.

"J. B. C." has opposed the entire centrifugal force to that of gravity, in receding from the equator towards the pole. But since these forces do not act in opposite or parallel directions to each other, the one being perpendicular to the earth's surface, and the other perpendicular to its axis,-it follows, that the entire force must be resolved in two directions; one of which will be that of a tangent to the latitude, and not in any way affecting the power of gravity; the other in a direction parallel to it, and is the only force opposed to gravity; which force is found to be equal to the entire force multiplied by the cosin. of the latitude, or equal to the centrifugal force at the equator, multiplied by the square of the cosin. of the latitude, and varies as the cosin. of the latitude of the place.

Hoping this communication may be found worthy of a place in the "Mechanics' Magazine," I remain, Sir, Yours, &c.

WM. MASON, Serjeant 6th Foot,

Chatham, June 22, 1829.

METROPOLITAN IMPROVEMENTS.

Sir, While so many improvements are going on in the metropolis at present, especially in regard to the streets of the city, it may be deemed impertinent to propose any more. It has, however, occurred to me, and I leave it to such of your readers as may feel inclined to take up the subject for the good of the thoroughfare, such as Cheapside,— public, that in all streets of great where great improvements are now being made, it would be of immense advantage to the foot passengers, were a part of the foot-path, or coach-way, appropriated solely to sweeps, dustmen, scavengers, and those who carry loads of goods, timber, iron, milk, &c., and marked off by a strong line of demarcation; so as to prevent the numerous accidents and endless confusion which

perpetually occur in a crowded street, by the unwary passengers coming in contact with bearers of loads of every description. This would greatly facilitate business, and prevent those scenes of riot and quarrel which frequently occur in the streets and courts of justice, in consequence of the injury many persons, especially females, receive by being pushed and driven aside by persons of the classes above mentioned. Besides, it would be more agreeable to those persons themselves; as they would not be so much impeded in their necessary progress, or be in danger of being run down by vehicles of every kind, as they often are when forced to take the coach-way in a crowded street. This suggestion would be of especial importance in making a footpath and roadway upon a bridge; and we hope that the proprietors of the New London Bridge will take it into consideration. The state of London Bridge at present, owing to the pulling down of the houses at the north end, is oftentimes appalling, from the danger which threatens the passengers, arising from the immense number of vehicles which cross it during the day. We suggest to the proprietors of the Southwark Bridge, whether, in such a state of things, if they were to reduce their tolls to one half, both for foot passengers and vehicles, they would not more than double their income by the change. They might, at least, try it for a month; and by giving due notice, we take it upon us to say, that they would not be losers. Even the proprietors of Waterloo Bridge might take this hint, and try the same plan: they could not lose much by the trial. I am, Sir, Yours, &c.

TREBOR.

GEOMETRICAL PROBLEM.

Sir,-Having for some time been a constant reader of your valuable Journal, I now send you an exercise (which I believe is original),

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Positions de Physique, on Résumé d'un Cours de Physique Generale; par A. Quetelet. 2 tom. 18mo. Bruxelles, H. Tarlier; Londres, Treüttel et Wurtz.

The spirit of inquiry which has been excited in this country by the publication of the treatises of the Useful Knowledge Society, has produced a demand for Elements, losophy without number. Compendiums, and Outlines of PhiEndless

Introductions have been written to all the sciences, insomuch, that we are afraid knowledge itself, instead of advancing, has begun to retrograde into first principles. We appear to be ever learning, and never able to come to the knowledge of truth. The elementary principles of natural philosophy have vestied, in a thousand different ways, been mangled, distorted, and traappetite of the ignorant multitude, to satisfy the artificial and depraved who think to arrive at knowledge by a sort of rapid process resembling the operations of steam in the arts, and despise the good old method of slow and patient investigation. Amid all this glare and glitter of science, this universal smattering which pervades the public, it is pleasant to meet now and then with a treatise which is really worthy of the attention of the philosopher, at the same time that it is attractive to those who are fond of short or royal paths to knowledge. It is not, however, in the English lan