The means resorted to by Perkins to produce this compression, viz., Bramah's Hydrostatic Pump, introduces us at once to the most remarkable mechanical property possessed by water, in common with all other fluids, which is that of transmitting pressure equally in all directions. Thus, if, into a close box filled with water, a pipe-the area of whose bore is half an inch-long enough to contain one pound of water, be introduced, the pressure upon the box, when water is put into the pipe, is not merely one pound, but one pound on every half-inch square of surface displayed by the vessel: so that if it be a cube of two feet, there will be a pressure upon it nearly equal to 7000 pounds; and this pressure may of course be immensely increased, without any addition of water, merely by lessening the diameter of the pipe and increasing its length. When we reflect upon the operation of this power, in the works of nature-when we imagine, for instance, a cavity in the interior of the earth filled with water, into which from a high mountain a narrow fissure empties itself, and see this fissure gradually charged with water from the melting of snows and other causes, we become aware of a power to which nothing could possibly oppose a successful resistance. We have heard that, in one of the Italian bays, there is a spring of fresh water which issues through the sea with such force that a ship passing near it would be turned from her course, and should she attempt to cross it would most surely be overset. The property of which we have just spoken, and the fact that there are towering mountains in the neighbourhood, will perhaps be sufficient to explain this phenomenon.

Of the various modifications of water,* viz., steam, snow, and ice, depending upon the presence or absence of caloric, much may be said. Heat lessening the attraction of cohesion, and thereby allowing the partial separation of the particles, most bodies are expanded by its presence, thus vapour occupies a greater space than the fluid from which it was produced; and Gay Lussac has demonstrated amongst others, that water when passing into steam expands to nearly 1700 times its volume. The contemplation of this fact would lead us to the steam-engine, and to the tremendous effects resulting from the admission of water to heated portions of the earth's interior, when, by the expansion of the steam there generated, mountains are rent and valleys upheaved. For the present, however, we must pass them by. Now, as the presence of caloric enlarges bodies, so a deprivation of it, as would naturally be expected, contracts them; but water at a certain temperature is a singular and most beautiful exception to this law; for when about to pass from the fluid to the solid state, it is found actually to expand. Now, mark the result of this exception.

If ice, following the general rule, became more dense than water, it would sink to the bottom, and speedily the whole body of water would be congealed, to the entire destruction of all living things therein; but from this expansion, becoming lighter than water, it necessarily floats upon the surface, and the process of congelation goes on slowly, and under such circumstances as almost to prevent it from ever reaching the bottom. Although our subject is far from exhausted, a few words on the amazing quantity of water upon the earth and we have finished. 129 million square miles-more than half the surface of the globe-are covered, it is

*We say modifications of water, but in reality it would be difficult to pronounce whether water is a modification of ice or ice of water. It is true that with us water is the more natural state; but it is as true that, if the temperature were sufficiently lowered, we should only see it in the shape of ice, except by the use of artificial means.

calculated, with water; and the quantity is said to be some thousand millions of cubic miles. From our ignorance however of the real depth of the sea, which has never been fathomed beyond one mile, any statement on this head must be hypothetical. Now, when we remember the amazing flood of water daily poured into the sea from the various rivers and other sources, we are surprised that it does not overflow its cliffs and ultimately swallow up the dry land; but it has been calculated by Dr. Halley, that every ten inches square of the ocean gives off one cubic inch of water in vapour every day, from which he estimates that 5280 million tons evaporate from the Mediterranean Sea alone during a warm day, probably to supply these very rivers.

All is changing-nothing remains at rest-whether our bodies, the earth that we inhabit, or the waters which surround it. The drop of water born to-day in the laboratory of the chemist is dissipated by the heat of the apartment, and in the shape of vapour is transported by the winds thousands of miles; it is congealed by cold, and descending in the shape of snow, assists to wrap up and protect the surface of the earth from the freezing blast; thawed by the sun of summer, it filtrates through the ground, and, with its fellows, bubbles forth a spring from the mountain side; the spring may become a river, and the river, after passing through its destined course, empties itself into the ocean, bearing with it our drop of of water, whence it is taken up by the atmosphere, again to pursue its round of usefulness.-So is it with all nature!

LIBRARIES, READING SOCIETIES, AND MUTUAL IMPROVEMENT CLASSES.

THE establishment of Libraries, and the formation of Mutual Improvement Classes, in some of the principal establishments of the metropolis, is one of the very gratifying results of the labours of the early-closing advocates. It is with deep concern that we witness the apathy that exists amongst very many young men on whose behalf the voice of entreaty is raised; and, to our minds, no better or more powerful proof of the malignant nature of protracted toil can be demanded than the stupifying influence it exerts, causing them to work on and on like mere animal machines, totally careless about the noble faculties that lie dormant within, and like a deadly sleeping draught, so destroying every energetic feeling that the very shout to life and liberty is deemed a pain and an offence. We do not know how this indifference is to be overcome, but by placing in the reach of such young men, in the most attractive and forcible manner, means for the cultivation of their mental and moral powers. Only let them realize, to the smallest extent, the satisfactory pleasure that results from mental occupation, and the pursuit of intellectual wealth, and we shall not number in our lists more strenuous supporters to the cause of early shop-shutting. Let them experience the real value of time devoted to such purposes

as these, and they will take no denial to their heartfelt importunities. None are so anxious to be freed from the pursuit of temporalities at a reasonable hour-none value so much the inestimable privilege of time to oneself as those who, with jealousy, occupy every moment of it in gratifying the cravings of the mind. And to a small extent we speak from experience, when we say that none perform their daily avocations with more method or spirit than those who know that the equanimity of mind they so much need, depends, to a great degree, upon the manner in which they have fulfilled their appointed tasks, and who will not allow any neglected duty to haunt them when with a good conscience they dismiss, for a brief and happy period, the world with its busy scenes, its clamour, and its strife.

Amongst the various popular methods held out to young men for purposes of self-culture, we do not know of any so well adapted as the three we have named above. A General Library seems to be the best, if not the only, means for the attainment of sound and useful information; for although in the present day of cheap publications every young man may, to a certain extent, stock his own book-shelves, yet it need hardly be said that few are in a position to form a collection of standard authors, or to sustain it by the addition of those important contributions that are from time to time added to our stores of knowledge. This inability is by no means an occasion for regret. Far greater advantages are secured by a number of individuals devoting an annual subscription for the formation and support of a general library than could possibly be obtained by the most extensive private assortment: because, on the one hand, if private libraries are selected with good judgment, the same authors of sterling worth would undoubtedly be included in each separate collection-whereas one or two copies of such authors would be sufficient for the students of a whole district; and, on the other hand, the possession of these would exclude others that are necessary, not merely to suit diversified taste, but even to constitute a good course of reading. There are very few private houses in which conveniences could be afforded for the reception of even a limited number of standard works, to say nothing of other miscellaneous productions; and it is of course out of the question to suppose that those various literary comforts to be met with in a well-arranged reading-room could be provided by any individual young man. A collection of books for private use should be made by every one, both as an evidence of literary taste, and because none but the most extensive public library could contain works adapted to personal views on religion and politics. It is not our intention for a moment to discountenance the practice of buying books for exclusive use; but merely to show that, while no private library is likely to be procured, adequate to the supply of a proper course of study, a general library is far superior, both as regards cheapness and utility.

A Reading Society does not possess the advantages of a Library. It has been urged by some that the very necessities of a book club are a source of its greatest good, inasmuch as the circumstance of the work being eligible but once we are compelled to read it then or never; whereas, when we are conscious that it can always be procured, we are likely to postpone our perusal, and perhaps to pass it over altogether. It is said, also, that the regular delivery of books induces regular habits, and compels to the equal allotment of our time for study. These compulsory principles are good for such as have but a small taste for literary pursuits, who possess a little indecision of character, and who

feel that they need goading over the difficulties that attend the pursuit of knowledge; but to those who not merely act from duty, but take a pleasure in the acquisition of learning, such forcing is unnecessary, and in a library the same rules can be voluntarily carried out. A Reading Society can however be instituted by young men possessing the most limited incomes, and does not, as in the case of a Library, require a large outlay of capital in the first instance--the current subscription being sufficient to commence upon. There is in the city, at the present time, a very flourishing Book Society, in connexion with a Mutual Improvement Association, where the quarterly subscription is only 1s. 6d. ; and yet, through the help of numbers, nearly all the Quarterly Reviews and a few of the best periodicals are circulated, in addition to other useful and entertaining volumes.

But Libraries and Book Societies owe a great deal of their importance to the influence of Classes formed for Mutual Improvement. In the first instance, it is the desire that each member of such a class feels to carry out its objects and the laudable emulation he experiences to produce the best essay on a given subject that induces him with so much ardour to ransack every volume that is likely to throw light upon the question; and, as it has been judiciously observed, that to read extensively, without reflection on the knowledge we are storing within, is as unwholesome to the mind as the indigestion of food would be to the body-so it must be acknowledged that no better means for stimulating the reflective faculties could be devised than the bringing forward all our information in the preparation of essays to be read before critical hearers.

It has been thought by many that to adults such means of self-culture as we have described are even superior in the improvement of the mind to those afforded by the usual routine of a scholastic education; and it may be safely affirmed, that they are far more calculated to promote an independent train of thought and a vigorous self-reliance-qualities than which none are more needed in the present day, when new and startling theories are being continually broached. It is moreover certain that, by consulting standard treatises on the different branches of knowledge, we enjoy the teaching of the ablest professors in the country; and it is equally certain that such teaching will be more indelibly fixed when, by close and patient attention, we have for ourselves followed and understood him, step by step, in the mysteries he is unfolding, than would be the case with the best oral instruction that could possibly be conveyed. Neither shall we have reason to fear the charge of being dull and slow of comprehension, so frequently made when, by a given period, we have been unable to explore the dark recesses of some difficult problem,—the time is our own, and the very calmness this conviction is calculated to produce would help us on greatly in the accomplishment of our purpose. The slowest perceptions are often the strongest, and the most ready-witted, who look but as it were on the surface of things, have not been the most famous either for originality or profundity of thought. It has been said of Andrew Fuller that, when pressed by Robert Hall with any very powerful argument produced by the latter on the impulse of the moment, he would remain silent, unable to meet it, but at length would exclaim, "Give me time, and I will reply." And yet we think, from what knowledge we possess of these two celebrated authors, that Andrew Fuller is more weighty than Robert Hall, though less ingenious and brilliant.

We do not wish however to insist upon it, that with these aids to

mental improvement we can beneficially dispense with the assistance of a tutor, writing, as we are, principally for those who have no choice in the matter; but we wish it to be distinctly understood that the most rapid strides may be made in intellectual growth by the instrumentality we have named, and that, used with a due sense of the exertion required on the part of the student, they may even produce greater benefits than would have been received under professional superintendence.

Such being our views, it will be our pleasing task to offer, in each number of our journal, hints that may be calculated to help the efficient working both of Mutual Improvement Classes and Reading Societies; and, as our usual "Review of Books" contains an analysis and examination of all works forwarded to us for that purpose, many of which are not adapted for a place in a library, we shall, under the department headed as at the commencement of this paper, present a Review of one or more newly-published books that may appropriately claim a place on the library shelves. We shall also feel it our duty, when any work of a peculiarly objectionable character is placed before the notice of the public, to caution our readers against it, not however without stating, in a clear manner and proper spirit, the reason for our objections. The price of the books we notice will be given, in addition to the usual information as to size and thickness. A list of books also, eligible for a Library, published up to the 10th of each month, will be added, with the price attached. We desire, in fact, to render our journal a useful guide for every description of Young Men's Societies; and, as we have engaged the assistance of the Editor of the Young Men's Magazine, who has hitherto taken a warm interest in these matters, we really hope to render this department of The Student a valuable one. We shall be happy to receive any communications from the secretaries or members of Young Men's Societies, offering suggestions of practical utility, giving an outline of the plans on which their proceedings are conducted, or on any other topic bearing distinctly upon this precise object. We hope also that our Prize Essay will be competed for by members of Young Men's Societies; and we shall be proud to insert not merely the name of the successful essayist, but also of the society to which he belongs.

BOOKS FOR LIBRARIES AND READING SOCIETIES.

KNIGHT'S WEEKLY VOLUME.

Nos. 2, 5, 21, 34, 43, 44, One Shilling each; Eighteenpence, cloth boards. It is now too late in the day to bestow praise on the spirited manner in which this novel publication is carried on. There is in circulation at the present time Murray's Home and Colonial Library, Whittaker's Popular Library, Clarke's Cabinet Series, and a monthly volume by Mr. Burns the publisher; and, without making an invidious comparison, Knight's volume, appearing though it does every week, is in point of price and excellence equal, if not superior, to any of them, judging at least as we do from the six volumes before us.

We have in the first place Volume 2-a miscellany most interesting, not merely from its contents, but from the fact of its being wholly composed by the factory girls in the mills at Lowell, an American city of some note on account of its manufactures. An extract from a letter of Miss Martineau's to Mr. Charles Knight will show that these girls do not exist under circum