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partizan of either. That portion of the work which is devoted to the investigation of the propagation, refraction, and reflection of light; the properties of mirrors and lenses; and the construction of optical and astronomical instruments, is clear and concise, while the investigation of formulæ for determining the foci of concave and convex mirrors, and also of the several descriptions of lenses, is simple and conclusive, and easily intelligible to those who have but a moderate knowledge of mathematics. The remaining chapters of this part of the work are devoted to the consideration of the interference, diffraction, and polarization of light, also double refraction, and the chromatic phenomena of polarized light. This part of the subject is of modern discovery and is highly interesting. The author has been happy in selecting from the voluminous writings of modern philosophers the most prominent and interesting parts of the subject, and has explained them so clearly as to make this difficult subject intelligible to ordinary capacities. We recommend this portion of his work to the careful perusal of our readers.
Section 2 of the second volume treats of heat in general, sensible and latent, and of its sources, propagation, radiation, and conduction; its effect on bodies in changing their form, altering their dimensions, and the various scientific applications of these properties to useful purposes. The conversion of liquids into highly elastic vapour, leads to the consideration of the nature, properties, and force of steam, and its efficiency as a motive power, which brings under review the construction and working of a steam engine. This is as well described as the limits of the work would allow. We take leave to suggest to the author or translator, when a second edition is required, that a description of a locomotive engine be added, and the working of it explained.
The construction and graduation of thermometers, and the application of those useful instruments, are very clearly described. Several useful tables will be found in this section, all of which have been judiciously reduced by the translator to Fahrenheit's scale, the numbers of the centrigrade division being put in juxtaposition.
The chemical formulæ (mathematically expressed) will also be useful.
The third section of this volume treats of magnetism in general: the singular properties of the loadstone, or the natural magnet, are described, as well as the method of communicating magnetism to bars of steel or iron. Polarity and the laws of attraction and repulsion of dissimilar and similar poles, are fully explained. The most valuable and important property of magnets, however, is their directive tendency; and in connection
with terrestrial magnetism, the dip of the needle as applicable to the purposes of navigation.
If the magnetic axis of the earth coincided with the axis of rotation, the magnetic needle would in all situations point to the North and South Poles. At the equator it would stand horizontal, at the poles vertical, and at intermediate places its dip would be proportionate to the latitude of the place of observation, but as this is not the case, the magnetic needle shows in different situations different quantities of declination, or variation, and the dip is not determinable by the latitude of the place. This circumstance would seem to impair the value of the needle as a directive instrument, but by mathematical processes the amount and direction of the deviation can be exactly computed; the observations can thence be corrected, and the full value of the instrument completely realized. M. Peschel appears to have consulted all the principal authorities on the subjects treated of, and ascribes to each his proper measure of credit. He has, however, omitted to notice the circumstances under which the dip of the needle was first discovered, and as the account is somewhat interesting, we quote it from an old work published in 1576, by Robert Norman, compass maker at Wapping, and called Newe Attractive.'
'Hauing made many and diuers compasses, and using alwaies to finish and end them before I touched the needle, I found continually, that after I had touched the yrons with the stone, that presently the north point thereof would bend, or decline, downwards under the horizon in some quantitie insomuch that to the flie of the compasse, which before was made equall, I was still constrained to put some small piece of waxe in the south part thereof, to counterpoise this declining, and to make it equal againe, which effect hauing many times passed my hands without any regard there unto, as ignorant of any such propertie in the stone, and not before hauing heard nor read of any such matter. It chaunced at length that there came to my hands an instrument to bee made with a needle of sixe inches long, which needle after I had pollished, cut off at just length, and made it to stand levell upon the pinne, so that nothing rested but onely the touching of it with the stone: when I had touched the same, presently the north part thereof declined downe in such sort, that being constrayned to cut away some of that part, to make it equall againe, in the end I cut it too short, and so spoyled the needle wherein I had taken so much paynes.
Hereby being stroken in some choller, I applyed myself to seek further into this effect, and making certayne learned and expert men (my friends) acquainted in this matter, they advised me to frame some instrument to make some exact tryal how much the needle touched with the stone would decline, or what greatest angle it would
make with the plaine of the horizon. Whereupon I made diligent proofs, &c.'
The annual and daily variations in the declination and dip of the magnetic needle have of late years been regarded of great importance, and magnetic observations are now almost as numerous as astronomical ones, and are regarded with an equal degree of interest. The details of the experiments, and of the results obtained by several of the most eminent European philosophers, will be found in this section of the work.
The subject of the last chapter of this section is, 'The artificial production of magnetism, the means of exciting and increasing it, and the different methods by which to enfeeble or destroy it altogether.' This is illustrated by numerous and highly satisfactory experiments.
We proceed to notice the third volume, which treats of electricity, electro-magnetism, and magneto-electricity. The two latter divisions of the subject may be regarded as modern sciences, being founded on discoveries made within the present century.
The phenomena of electricity, like those of light, are the subject of two distinct theories. Some philosophers, as Franklin and Priestley, maintaining that there are two kinds of electricity, which they call vitrious and resinous, while the moderns, as Faraday, and others, assert that there is but one, and that the phenomena result from the excess, or deficiency of it in the body acted on. The states of the body in relation to electricity are designated plus or minus. Much controversy has arisen on the subject of these theories among modern philosophers, without, however, any satisfactory conclusion being arrived at. As in general the phenomena may be explained on either theory, the fact, in itself, affords only a presumptive proof of the hypothesis adopted. The author candidly and clearly states both theories, but as he appears to be more anxious to develop principles, and establish facts, than to exhibit himself as the advocate of a philosophical creed, he dismisses the subject very cursorily, and proceeds at once to an exposition of electrical phenomena in general. The whole subject, including most of the discoveries made by Volta, Woolaston, Davy, Faraday, etc., together with descriptions of improved apparatus, and of many interesting experiments, is (without sacrifice of perspicuity) condensed into one hundred and eighty-six pages. We had proposed to give an analysis of this portion of the work, but the heads of reference were found so numerous, the subjects so interesting, and the account given so concise, though clear, that to analyze would be to transcribe the greater portion of the work. We must therefore content ourselves with referring to the work itself. Section
V., which is the last portion of the work, is on electro dynamics, a subject, as before stated, altogether the result of modern discovery. The first germ of this science was produced by Professor Oersted, of Copenhagen, as appears by the following
Ritter and Yelin, in the last century, threw out some conjectures as to the internal connexion between electricity and magnetism, and their probable identity; but it was not until 1820 that Oersted, of Copenhagen, discovered the first effects of an electro-magnetic, and in 1832, Faraday those of a magneto-electric character.
'The first discovery made by Oersted, by which the road to this fertile field of science was first laid open to philosophers, consisted in this; that an electric current transmitted near to a magnetic needle deflects it from its normal position. This deflexion, which at first seemed either to occur or fail in a manner altogether peculiar and uncertain, was found, on closer examination, to obey a universal and unvarying law; which is thus expressed in Ampère's brief and universal terms: That the north pole of a magnet is invariably deflected to the left of the current which passes between the needle and the observer, who is to have his face towards the needle, the electric current being supposed to enter near his feet, and to pass out near his head.
No discovery in natural science excited more general and lively interest than Oersted's. The most distinguished philosophers throughout the world recognised its importance, and endeavoured, by repeating and varying its experiments, to trace still further this extraordinary property of electricity. They hoped, by means of Oersted's fundamental experiments, they should be enabled to unravel the mystery in which the connexion between electricity and magnetism had hitherto been shrouded. New facts were sought for experimentally, which might serve as indisputable evidence of the identity of electricity and magnetism, or from which it might be proved that both were merely modifications of the same fundamental force. Although the object thus earnestly desired has not yet been attained, the active spirit of inquiry that has been called forth has led to important and approximating conclusions. Ampère, who considered Oersted's experiments from a point of view common to them all, selected the mutual relation of electric currents to each other for the special subject of his investigations. He was led to the important discovery that the electricities in a state of motion, i.e., as electric currents, act attractively and repulsively on each other according to a certain law, in a manner resembling the polar attraction of statical electricity, i.e. of electricity in a state of tension.'
From the period of Oersted's discovery to the present time, the transactions of learned societies, scientific memoirs, and journals of science, have abounded with the researches and discoveries of the most eminent philosophers of modern times, indeed there are few men of any scientific character but have
devoted much attention to this important subject. Many and important are the practical results of these inquiries, among which may be named, as not the least, the electric telegraph. The author of this little work has shown himself to be a man of considerable acuteness, of great industry, and of consummate skill in searching out and arranging, with much scientific consecutiveness, the vast array of facts he has brought together, derived from such voluminous and wide-spread sources.
The work, though consisting only of three small volumes, may be regarded as a magazine of scientific facts alike valuable to the adept and the student. Mr. West has done good service to the English reader by presenting it to him in his native tongue. We thank him for his labour, and shall be glad to find that the public continues to appreciate it aright.
Art. VI. Every Eye shall see Him;' or, Prince Albert's Visit to Liverpool, used in Illustration of the Second Coming of Christ. A Sermon, preached in Saint Jude's Church, on the second day of August, 1846, the Sunday next after the Prince's visit. By the Rev. Hugh M'Neile, M.A., Hon. Canon of Chester, and Incumbent of St. Jude's, Liverpool. (Published by desire, for the Liverpool Sailor's Home.) Third Edition. London: John Hatchard and Son.
It is not our custom to notice single sermons. The peculiarity of this one must be our excuse. It is little likely to become a precedent. Nor is it any pleasure to us to speak, as we must speak, of this production. Mr. M'Neile is a man, in many respects, worthy of honour. We differ widely from him on some important subjects, but we believe him honest, able, and desirous to do good. He has, and deserves to have, great influence. But while this makes our present task painful, it, at the same time, urges us to its performance. Bad practices, as bad systems, find the best and strongest support in good men, and the fly in the pot of ointment is the worse for being there. Masters of Arts, and Hon. Canons, must not be allowed to commit 'folly in Israel.'
It is easy to understand that this sermon is far from what the author could wish.' But we cannot admit the confession of imperfection as an excuse for publishing. Before authors can employ such a plea, they ought to shew that publication is necessary. It is true that in the present instance it was solicited. The idea of taking advantage of popular excitement to obtain some addition of funds to an institution, was too pleasant