« SebelumnyaLanjutkan »
our climate, the high price of fuel, the nature of our manufactories, where warmth is as much required for the work as for the workmen, and the danger from fire; that a Treatise, containing any useful information in so important a branch of science, will be eagerly sought after, and examined with care, by the practical mechanic, as well as by the scientific engineer.
Having never seen a practical Treatise on warming and ventilating, applicable to domestic purposes, which deserved the title of a standard work, we were anxious to ascertain the manner in which Mr. Tredgold had treated the subject which he had undertaken to illustrate, being convinced that it is one of great importance to the comfort and welfare of society.
A subject of this nature cannot be pursued with advantage without the aid of science; but, to render it useful, without involving the reader in investigations, the necessary mathematical reasoning is confined to the notes, and introduced only where the omission would have been improper. The work is divided into twelve chapters. The first contains a popular comparison of the different modes of applying heat to warm rooms, &c. The author is in favour of open fires, but recommends heat produced from steam for the passages, particularly where they lead to large rooms. The second chapter is devoted to examining the qualities of different kinds of fuel; the various experiments on their effects are collected, and the methods of calculating their powers explained.
The third chapter treats of the laws of cooling, and is illustrated by some original experiments by the author. The important subject of ventilation is fully discussed in the next chapter, and the causes of the loss of heat investigated.
The fifth and sixth chapters relate to the construction of boilers, fire-places, and steam-apparatus, pointing out the best materials for these various purposes. Such information will be important to the practical mechanic; and he will be able, by proper attention, to guard against the failure of pipes, &c., which have been common, in consequence of using lead and other improper substances.
The seventh and eighth chapters contain practical examples of the application of heat from steam to dwelling-houses, churches, schools, hospitals, &c. The author has suggested the means of giving the advantage of a milder climate to consumptive patients in page 179.
The ninth chapter describes the best method of constructing stoves, hot-houses, and conservatories for plants, with examples of the application of heat from steam. This interesting subject has never before been so fully considered.
The tenth chapter treats of the construction of grates for
open-fires, and of the ventilation of rooms heated in that manner.
The art of drying, for the use of the manufacturer, as well as for domestic purposes, is treated in the next chapter.
In the following, and concluding chapter, the author has given his own views of the nature of heat and light; he conceives them to be the same fluid, in different states of mechanical action, and has collected a variety of examples to explain the phenomena.
The work is illustrated by nine plates, with descriptions, and various useful tables respecting heat, and its application. A work, comprising so many interesting topics, cannot fail of exciting considerable expectation, especially as the former works of the author have been well received by the public; and one of them, though of recent date, has already arrived at a second edition. The author's mathematical knowledge seems to be of the superior order, and all his experiments appear to be conducted with great care, in order to ascertain facts, without reference to any assumed or favourite hypothesis. He has availed himself of the labours of others; he has examined their opinions and practice with candour, and has passed an impartial judgment upon them, by pointing out what he approves, and by stating where he differs from them; assigning his reasons, and giving the result of his own researches in a clear, concise, and respectable form. The book may be consulted with advantage, not only by the manufacturer, but also by the projectors of extensive buildings, where heat and ventilation are important considerations.
There can be no doubt, that, on a small scale, the application of steam would be too expensive, and the attention required would be found inconvenient; but, on an enlarged scale, steam offers many advantages, both as to the effect of heat, wholesomeness of the air for respiration, and security from accident by fire. We shall always be glad to notice publications issuing from the press, which offer any addition to the stock of science already before the public. The comparative statements in the work before us, and the many useful calculations, which exhibit, in a favourable point of view, the ability, care, and industry of the author, will be valued as they ought, by those who require such information; and will form a safé guide to those who may be disposed to direct their attention to a further consideration of the subject. In the chapter on Ventilation, he observes :
" That a pure atmosphere is necessary to preserve health, I need not attempt to prove by reasoning; it is a truth universally known and acknowledged: but it will be proper to examine, and estimate the effects of those causes, which render confined air impure, and unfit for supporting life. It has been remarked, that the salubrity and healthy state of the air depend, in a great measure, on the quantity of oxygen gas it contains ; and this quantity appears to exist in all places exposed to a free atmosphere, and the influence of winds: but the same uniformity of composition does not prevail in the confined air of dwelling-houses, crowded theatres, and hospitals, that are badly ventilated. Yet, the chemist who wrote this remark, was not able to detect an appreciable difference between the air of an hospital and that of an open situation; and the same thing is averred by other chemists. Sequin tried the air of an hospital, the odour of which was disagreeable, but it gave him the same result as the external air. The researches of Priestley, De Marté, Gay Lusac, and others, all tend to establish the same result; which is, that the composition of the atmosphere is essentially the same every where. If you allow these experiments to be correct, they only prove, that a deadly poison may be diffused through the atmosphere, which the art of the chemist cannot detect; but of which, we have better evidence than is given by the nicest tests of the analy. tical chemist, in the pale visages and weakly constitutions of the inhabitants of low and crowded cities; in the unhealthiness of particular districts ; and in the important alteration which a change of residence often produces in individuals unaccustomed to such changes. If there be no variation in the quantity of oxygen, some other means should be taken to enable us to know, what the difference consists in ; perhaps, it is the presence of foreign ingredients; these should be tested for. The atmosphere in the neighbourhood of the sea is said to contain muriatic acid. The subject is too interesting to remain at a stand ; nd, if it were once entered upon with a Wollaston's delicacy of analysis, we might expect much important information.”
On the nature of heat, his observations are no less worthy of attention:
“ On the assumption that heat is a material fluid, when it combines with any other matter, the combination may exist in these states ; and these states must depend on the relative quantities of heat which enter into combination with the other matter. First,—when the quantity of matter is abundant in proportion to the quantity of heat, and the union of the parts, by their attraction, is vastly superior to their affinity for the beat interspersed among them: in this state, the body is a solid. Secondly-If the quantity of heat be increased in the surrounding bodies, this solid must also absorb its specific quantity to preserve the equilibrium; and the temperature may be increased to such a degree, that its cohesive powers may be balanced by its affinity for heat : in this state, the body is fluid. And, thirdly— The temperature of a fluid may be increased till each particle beconies surrounded by an atmosphere of heat, which retains the particles at so great a distance from one another, that their force of attraction is insensible: the body is then in the state of gas. Hence it is that bodies assume those states at particular temperatures only; and the peculiar temperatures of each body must depend on the relation be iween its attraction of cohesion and its affinity for heat. A portion of heat enters into combination with the body at each of these changes, and which is called latent heat; or, perhaps, with greater propriety, combined heat. If two particles of the same matter be at a given distance in the fluid state, and attract each other with a power varying in any inverse ratio of the distance, and the caloric which retained them in equilibrium in the Auid be removed by the attraction of surrounding bodies, the particles must evidently coalesce with momentum: consequently, the rapid abstraction of heat muşt always render the contact most intimate; and when this is done to a certain extent, there are bodies where the affinity for heat is not sufficient to restore them to the natural equilibrium, unless they be subjected to an elevated lemperature. The theory of annealing depends on this principle.”
Redgauntlet ; a Tale of the Eighteenth Century. By the
Author of Waverley. 3 vols. We are induced to offer a few remarks on the work before us, in consequence of the high estimation in which its author is held by the public; but in doing this, we beg at the same time to state, that it is not our intention to notice analytically, all the novels and romances which issue daily from the press. We shall notice works of fiction, whenever we find that they contain any thing likely to add to our knowledge of the human character, or any thing interesting to society at large. We must confess, that the greuter number of such works, which are now daily brought forth into the world, are void of these things ; when we have read one, we may say that we have read them all. Similar characters are drawn, similar plots laid, similar escapes occur, and similar results eventually take place, without any regard to time, place, or circumstances. Such works, which are the offspring of a wild, uncontrolled imagination, can only lead the youthful mind away from the paths of duty, and load it with a heap of Quixotic notions of occurrences, which never take place among mankind.
One object of works of fiction is, to rouse the mind to a love of every thing that is noble, good, and virtuous; and to an abhorrence of every thing mean, base, and sordid. Every author endeavours to accomplish this in a certain degree, in the delineation of his characters. But, fictitious writings ought to have another object in view ; that is, to exhibit a real picture of the human character, as we find it in society, modified by customs and manners. There are innumerable degrees observable in the characters of mankind, between the most just, upright, and noble, and the most base and perfidious. These intermediate ones, some of which
be said to be a compound of good and bad, are frequently overlooked altogether in works of romances, and in novels. Most fictitious ones are represented as of the height of perfection, or else of the basest kind. Very few authors have an opportunity, or, at least, take the trouble, to metamorphose themselves from one order of society into another, so as to become sufficiently acquainted with the customs, manners, and different habits, of every class, in order to lay a correct picture of them before the world.
A knowledge of human nature can only be acquired by intercourse with mankind in every station of society. It was from a knowledge of this kind, that Fielding, Richardson, and Smollett, were able to draw such a correct portrait of the human character, which the hand of time has not been able to deface. We have always thought, and we still think the same, that a correct judgment, founded on our knowledge of dispositions and habits of mankind, in the different grades of society, is more necessary than an inventive genius for the exposition of characters in works of fiction. This is proved to us every day, by observing the writings of different authors, where wild and romantic occurrences are represented to take place, regardless of time, place, and possibility.
But we have no reason to charge the author of “ The Redgauntlet” of giving way to these ideal flights; as the characters represented there, are such as are frequently to be met with among mankind.
The writer of fiction may fall into an opposite error, which is, that of describing such things as happen every day. Before the reader can find any interest or amusement in perusing a work, whether it contain facts or fiction, he must meet with something which does not constantly strike his senses. If a person were to write a history of all the common occurrences with which he is daily surrounded, he would find po one desirous of perusing his work, although it contain a recital of facts; much less would a fictitious work of a similar character, amuse or interest. It is necessary, therefore, that a novel or romance should, before it can amuse the reader, give a description of such characters and occurrences as we do not frequently meet with. It should, however, keep within the bounds of probability, and have some interesting subject, whether real or imaginary, for its foundation. The author of the “ Redgauntlet,” has steered clear of both these extremities; but we cannot say so much for the author of "St. Ronan's Well." But, as we have nothing to do at