abode of guilt, where humanity, mankind, and reafon, have been fo often violated.'

In the thirtieth number, we find a defcription of the department of the Eure and the Loire, which, in the old maps of France, is diftinguished by the name of Beauce; it is a level open country, badly fupplied with water, and scarcely a tree is to be feen but it is very fertile in grain. Its principal town, Chartres, is ill built, and remarkable only for the fabulous ftories told concerning its great antiquity; for it is faid to have been founded, foon after the deluge, by the defcendants of Gomer, the eldest fon of Japhet. Dreux is rendered famous by the bloody battle fought near it, during the minority of Charles IX. between the catholics and the proteftants, in which the latter were defeated. The catholics, we are here told, were indebted for this victory, not fo much to the valour of their troops, nor to the prudence of their Generals, as to a repartee of the Queen. When the prince of Condé first offered battle, the Generals of the royalifts declined it; and, had the prince taken advantage of their undecifive conduct, it is pro bable that he might have routed them: but, unfortunately, he allowed them time to fend to court for fresh orders. When their meffengers acquainted Catharine with their embarraffinent, fhe vouchfafed not to give them an anfwer, but, turning her back on them, faid to Charles's nurfe, Here are Generals indeed, who fend to ask a woman and an infant whether they shail give battle! What think you of it, nurfe? This farcafm determined the Generals to attack. When the conftable Montmorenci was taken prifoner in the beginning of the engagement, news was carried to the Queen that the battle was loft; on which she faid, with apparent unconcern, Well, then, the worst of it is that we must say our prayers in French.

The two following numbers contain an account of the department of the Eure, and of that of the Calvados: the former is not lefs remarkable for the beauty of the country than for its fertility; it contains the towns of Evreux, Bernai Pontaudemer, Louviers, Andelis, Gifors, and Verneuil : the inhabitants are industrious, and are employed in various manufactures, particularly those of cloths and ftuffs, and in bleaching linen. On the weft of this department, lies that of the Calvados; Caen, its capital, is one of the fineft cities in France; its caftle was built by the English.

In perufing what we have hitherto feen of this work, we have often had occafion to admire the talents of the writer, and particularly his style in description; the only complaint that we can make, is that he fometimes gives up the reins too freely to his imagination, and too frequently attempts to be picturesque

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and fublime. The paffage which we tranflated is really beau tiful; and a few fuch, properly introduced, have a happy effect but this effect is greatly diminished when they occur too often, and when, inftead of being the spontaneous effufions of a mind occafionally elevated by the contemplation of ftriking fcenes, or by the recollection of great and affecting events, they appear to be the refult of a ftudied effort to bear the reader, on the wings of imagination, far above that level which is best calculated for beholding objects in their proper forms, and in their true colours.

ART. VIII. Algemeene Eigenschappen, &c. i.e. The general Properties of Electricity explained; or Inftructions relative to Electrical Machines and Experiments. By JOHN CUTHBERTSON, Philofophical Inflrument-maker. Svo. pp. 166. Amfterdam. 1794. ABOUT fourteen years ago, this ingenious artist published a

volume under the fame title with the prefent, which contained a description of the electrical machines and apparatus that he had then conftructed, with plain inftructions for making experiments to illuftrate the principles of this curious branch of phyfics. About two years afterward, having fo far fucceeded in his endeavours to improve his machines, that he had made them as powerful again in their effects as they were before, he gave an account of thefe improvements in a fecond volume. Since that time, his indefatigable attention to this fubject having enabled him to render them much more perfect, he has defcribed thefe meliorations in the work now before us; which, on this account, we cannot help confidering as a valuable gift to his Dutch friends, on his leaving Holland to fettle in London.

The first part of the prefent volume contains a narrative of the author's endeavours to improve electrical rubbers. We muft here refer the reader to an account of Dr. Van Marum's newly improved cufhions, which he will find in the appendix to our eightieth volume, page 602, and in which it was faid that the Doctor found the exciting power of his rubbers to be, to thofe of Mr. CUTHBERTSON, as feven to feventeen. Justice, however, obliges us to obferve that, from the account here given, and which, from experiments that we have ourselves made, we know to be true, this fuperiority was not the refult of any peculiar excellence in the conftruction of the Doctor's rubbers, but merely of his ufing Kienmayer's amalgama, with which our author was at that time unacquainted; for, with this amalgama, Mr. CUTHBERTSON found that his own rubbers were equal, and even fuperior, to the Doctor's; which, from being mounted

mounted with much brafs and fteel, were liable to fome unavoidable imperfections. We then hinted that we feared he would find the friction attending them too powerful to be applied to his grand machine; and we here learn that our conjecture was well founded.

Mr. C.'s narrative is followed by fome very ingenious experi ments, to illuftrate the manner in which rubbers act; whence it appears that the glafs, while paffing under the cufhion, becomes negative on both fides, but most fo on that fide which is excited; whence we may conclude that plates, which admit of an equal friction on both fides, are more advantageous than cylinders the furface of the rubber fhould be perfectly level and prefs equally on that of the glafs, and particular care must be taken that the anterior part does not prefs lefs than the pofterior.

The author next defcribes the machine, with its rubbers, as he now ufually makes it, with the axis turning between mahogany pillars: but he has alfo fitted up fome, in which the axis is infulated, by being fufpended between glafs columns;an account of one of this kind was published, by Mefirs. Deiman and Troofwyk, about five years ago, and was mentioned in the appendix to the fecond volume of our new feries. To give a particular defcription of the conftruction, without the affiftance of engravings, would be difficult; there are numberlefs little circumftances, which the experienced electrician knows to be of importance, in the form and arrangement of the several parts of a machine, but which to others appear trifling; it is fufficient to obferve that the machines here defcribed excel all others that we have feen, in the equal and ftrong preffure of the rubbers, in the convenient difpofition of the apparatus, and, as we fhall prefently have occafion to fhew, in powerful effect.

Mr. CUTHBERTSON proceeds to examine the merits of an electrical machine conftructed under the direction of Dr. Van Marum, which the reader will find mentioned in the appendix to our fifth volume, N. S. In this machine, the plate of which is thirty-two inches in diameter, he obferves that the rubbers, being nine inches long, approach too near to the axis; he then describes fome very fimple and ingenious experiments, which he performed in order to afcertain the most advantageous length of the cushions in proportion to the diameter of the plate, and by which he found that, for one of thirty-two inches, the rubbers ought not to be longer than feven inches. Other defects, obferved by our author, are that the baked wood, by which the axis is infulated, is liable to imbibe moisture, notwithstanding all the precautions that can be taken by covering it with electric fubftances, and that, becaufe the axis is fupported only at one end, it is apt to become unsteady, in confequence of fre

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quent ufe. That the fame conductor may be made to exhibit either pofitive or negative electricity, is not fo advantageous as it may at first appear; for there are many experiments in which feparate conductors are abfolutely neceffary; and thefe cannot conveniently be applied to this machine, in its prefent ftate; though we conceive that a trifling alteration might remove this defect.

In our account of Dr. Van Marum's rubbers, we described the manner in which Kienmayer's amalgama is made, and in which the Doctor applied it: Mr. CUTHBERTSON finds it more advantage us to mix up the amalgama with laid, to the confiftence of an unguent, which must be fpread on the rubber fo as to form a furface perfectly level. His directions for fixing the rubbers, and for regulating their preffure, are judicious. The preffure recommended for a machine, the plates of which are thirty-two inches in diameter, with four pair of rubbers, is eftimated at nearly eight pounds; or, in other words, the rub, bers ought to be fo adjusted, that, when the winch is placed in a horizontal direction, a weight of eight pounds, fufpended to it, fhall draw it down.

The author next defcribes his mode of afcertaining the power of a machine, and of comparing that of different machines: this he does with a jar, containing about 160 fquare inches of coated glafs, mounted with an electrometer, on the fame principle with that invented by Mr. Lane: but, as jars, of equal fize and furface are not always equal with refpect to the charge which they will receive and contain, Mr. CUTHBERTSON always tries his machines by the fame jar, and keeps one, as a ftandard, for this purpose: the brass balls of the electrometer being fet at half an inch diftance from each other, the power of the machine is calculated to be inverfely as the number of revolutions neceffary to make this jar ditcharge five times. He has given a table of the powers of his machines thus estimated; which, as it illuftrates the improvements that he has made in them, and the great advantage refulting from Kienmayer's amalgama, we shall infert :

The other mode of comparing machines is by computing the number of revolutions required to charge a jar, like the former, fo high that its difcharge may melt five inches of the fmallest iron wire, which is about th of an inch in diameter: for this purpose, Mr. CUTHBERTSON has contrived a very fimple and commodious apparatus. The number of revolutions of his latest machines, requifite for producing this effect, is exactly the fame with what is neceffary to produce the five difcharges of the standard jar above mentioned.

In both these ways, Mr. CUTHBERTSON has compared the machine, conftructed by Dr. Van Marum, with his own: according to the Doctor's account, four revolutions of his glafs plate made the standard jar discharge five times, when the brafs knobs of the electrometer were half an inch distant from each other. Now according to the above table, two plates, of 31 inches each, will do this in a revolution and a half; confequently, a fingle plate will effect it in three revolutions: but, in order to make this comparison with greater accuracy, our author formed two machines, with each a fingle plate of twentyfour inches diameter, one conftru&ed in the manner directed by the Doctor, the other, in his own way. The length of the fpark, drawn from the conductors, appears to have been the fame with both machines; that from the pofitive being 71, and from the negative 5 inches. In order to discharge the ftandard jar five times, when connected with the pofitive conductor, the machine of the Doctor's conftruction required 4 revolutions, and that of our author's, 4: but, when the jar was connected with the negative conductor, both machines required five revolutions. With the first mentioned machine, feven revolutions charged a jar, placed at the pofitive conductor, fo as to melt five inches of the smallest iron wire; and, at the negative conductor, twenty-two revolutions were neceffary to melt four inches; with the latter, feven revolutions were fufficient to make the jar, when charged pofitively, melt fix inches; and fifteen, when negatively charged, to melt five inches of the wire. A difadvantage attending the Doctor's conftruction is that it is more expenfive than the other.

One of the most interefting parts of the prefent work is that which relates to the charging of coated glass. Till lately, it was not known that a fingle jar could be charged fo highly as to melt iron wire; we mentioned this circumftance, together with the neceffity of the uncoated glafs being a little damp, in a former article, to which we refer the reader *. Mr. CUTHBERTSON has fince found that, with a machine with two plates of

* Rev. New Series, vol. ii. p. 545•

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