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neighbourhood; in which above eleven thousand persons bad
Some of the nobles of the Ukraine have, at length, per-
i.e, An Oration on the Character and Genius of the Arabians.
design is, to recommend that branch of science in which he
instruct his hearers. He introduces his fubje& by an applica. tion of the maxim of Horace ;
EN modus in rebus, funt certi denique fines,
Quos ultra citraque nequit consistere rectum. And he observes, that the little attention generally paid to the study of Arabic, may, in a great measure, be ascribed to the violation of this wise maxim, by those who are enthufiaftic admirers of that language, and the works extant in it, as well as by those who, by affeding to treat both with contempi, endeavour to excuse their own want of application. The arguments of the latter class are by no means formidable, as it is ealy to refute that calumny, which has its source in ignorance and iodolence; but it is difficult to recommend the object of exaggesated praise to the attention of the unprejudiced and impartia! enquirer.
In forming an estimate of the literary works of any people, it is proper to attend to the influence of their national characier and manners on their studies and pursuits. This, the Profesor thinks, has been too much neglected, and therefore be proposes to consider, in this point of view, the Arabs who lived before the Mahometan Æra; in order to shew the conformity of their Aational character to that kind of knowlege which was then cultivated among them.
But, though the exigencies and pursuits of a people are determined by their national character, yet this has also its causes, on which it depends for its various modifications and degrees of activity: these causes are either natural, as bodily constitution, climate, or age; or political, as form of government, language, education, manners, religion, and commerce with other nations. ! The Professor has briefly, but judiciously, examined the in• Auence of each of these circumstance in forming the character of the Arabs, which, he concludes, is exactly conformable to the divine predi&tion concerning Ihmael, in Genesis, xvi. 12. and admirably illustrated by the sublime description of the Onager, or wild ass, in Job, xxxix. s. Such, to this day, is the character of the roving Arabs, who conftitute the moft confiderable part of the nation. Their history abounds with inftances of åkalted virtues, and of atrocious crimes. They are remarkable for their hospitality, generosity, and inviolable fidelity; but these, as well as their capacity, cruelty, and love of revenge, are the consequence of their national manners and mode of lite
. Their virtues therefore are not the fruit of philosophical culture, but the spontaneous produce of nature; but with respect to promptitude and magnanimity, they inspire a vigour of exertion, which more refined manners seldom confer. Irresolution fuits not the disposition of an Arab. He never hesitates long, whether he thall perform a kind office to a friend, or Thed the
blood of an enemy. If an opportunity offers of doing both, it renders him completely satisfied; but, if the gratification of his revenge happens to come into competition with an act of generofity, he will instantly give the preference to the latter, and derive a pride from the consciousness of having done his duty. To exemplify this, the Profeffor relates the following story:
Hassan, the Scenite, hospitably received into his tent, Ibrahim, a chief of a neighbouring district, who, driven from his country, was obliged to seek shelter in the desert. Afrer some days spent in cheerful festivity, the stranger, wishing to depart, requested his host to accompany him a part of his way. The latter consented; but, while preparations were made for the journey, he examined his lance with peculiar attention, and his eyes glowed with anger and revenge, as he eagerly sharpened his sword. “Thou seemeft," said Ibrahim, “ to thirst for blood. Who is thine enemy? He shall be mine."-" That tyrant, Ibrahim," answered Hassan, “ who shed my father's blood. His power has long screened him from my revenge; but now he is a wandering exile, I will not reft till' I have found him.”_" Thou haft found him!” was the reply; “ I am the wrecch who killed thy father : behold in me the object of thy vengeance !”_" Thou, Ibrahim? by Alla and his prophet! But, thou art my guest! I had set apart this money to provide for thy journey. Take it while thou mayest, and go thy way.”
From a people thus circumstanced, the Profeffor observes, no great proficiency in arts or science could be expected; and when, in later ages, under the dominion of the Caliphs, they were excited, by honours and rewards, to such studies, the native fire of their genius, though it could not be entirely extinguished, was damped by the influence of tyranny, superstition, and luxury. Hence, though the present, with respect to learning and learned men, might be styled the golden age; yet the distinguishing and characteristic merit of the Arabs must be confined within those periods, in which their genius was the . untaught but vigorous offspring of nature.
In the remaining part of this oration, M. SCHULTENS briefly insists on the peculiar fitness of their language for poetical expression, on their natural turn for eloquence, and passion for poetry; together with the circumstances by which these qualities were cherished, and the objects by which they were excited; but, as his ideas on these subjects are coincident with those of the best modern writers, among whom we may mention Sir William Jones and M. Herder, we shall bere close this article, by acknowleging the entertainment which we have received from perusing the work.
ART. VI. Lettre de M. VAN MARUM à Monf. le Chevalier MARSILIO LA8
DRIANI, &c. i. e. Letter from Doctor VAN MARUM to che Chevalier MARSILIO LANDRIANI, containing a Description of Electrical Rubbers of a new Construction. 4to. 8 Pages. Haarlem. 1789.
TO withstanding the many improvements made, within a few
remains to be done, in order to bring them to that degree of perfection, of which we may suppose them capable. For researches of this nature, Dr. Ván MARUM is advantageously circumfanced, from his having the direction of the largest and mck powerful apparatus hitherto known *. In performing experiments with onis machine, he found that the effect of it, when strongly excited, was confiderably diminished by the return of the electric fluid to the anterior part of the rubber.
This in convenience was before noticed, in the Philosophical Tranjac. tions, vol. LXII. by Dr. Nooth, who there gives some directions for its removal. See Review, vol. li. page 223. On these hints, Dr. Van MARUM has improved ; and, after a great number of trials, has constructed rubbers which are free from this fault, and which, therefore, produce a much greater
effea than the fort commonly used.
In the description of his rubbers, the Doctor is exceedingly minuie; but, wishout a plate, it is impossible to give our readers any other than a very general idea of their construction. The pair, here described, were made for a machine with a glass plare thirty-two inches in diameter, and are ten inches long: the furface in contact with the glass, is of oiled folk, which, about an inch from its posterior edge, is covered with a thin smooth coating of amalgama: this is made to press equally in all its points on the glass, by a parallelopiped of wood, formed as exad and smooth as possible, which the Doctor calls a Preffer, and which is covered, on the surface toward the rubber, with the thickest silk velvet that can be procured. The preffers are con nected, by means of a hinge in the middle of the back of each, with a pair of strong springs, which, at their oppofiie ends, are each joined by another hinge, to a brass plate, and thus regulated by a single screw, placed between this and the circumference of the glass plate. The oiled folk is cut nearly square, about twelve inches each way; and its amalgamized part is faftened to a braís plate on the posterior edge of the preffer, but somewhat longer than this; and into its further end, is fixed, at right angles with it, a rod of the same metal, on which the insulating part of the fiik is extended parallel to the furface of the excited glass, so
as to adhere closely to it, without being rumpled by the rotation of the machine.
In these rubbers, it is of importance that the oiled folk be very smooth, and free from all irregularities of surface, which not only impede the equal friction of the amalgama against the glass, but also prevent the insulating part from adhering so closely to the excited surface, as is necessary to hinder the electric Auid from returning to the rubber : the filk which the Doctor uses, is made ar Leipzic.
Of like importance is it, that the coating of amalgama, laid on the exciting part of the filk, be very thin and smooth; on its anterior part, its thickness should gradually diminish so as that its edge may be scarcely perceptible. Dr. VAN MARUM uses the amalgama recommended by Baron Kienmayer of Vienna, which is preferable to any hitherto known: it confiits of one part of puufied zinc, one of tin, and two of mercury. The zinc and in are melted in an iron ladle, and the mercury added to them, as soon as they are taken off the fire: the mixture must be stirred with an iron spatula, and, when cold, reduced to a very fine powder, in a glass or marble mortar. Some varnish being laid on the filk, this powder is sprinkled on it, by means of a fine fieve; and, when dry, that which adheres is polished by rubbing it with a steel burnisher; after which a drop of sweet oil is laid on its surface.
The Doctor compared the effect of his new rubbers with that produced by the common fort, by examining the number of revolutions which his machine required, with each kind, to charge a jar, containing a square foot of coated glass, to a certain height, determined by Lane's ele&rometer; the balls of which were, in these experiments, fixed at half an inch distance. This, with a pair of his old rubbers, was effected in seven or eight revolutions; and, with those here described, in one revolution and an half; with these also, the jar discharged itself, on the ball of the electrometer, ten times in sixteen revolutions, to effect which, with a pair of the common rubbers, above eighty were required. A battery of fifteen square feet of coated glass was charged, so as to explode spontaneously in fixteen revolutions, with the new rubbers; and the Doctor found, by his papers, that, in frofty weather, with Teyler's grand machine, which has four pair of common rubbers, he did the same in eleven revolutions; and the degree of the charge, in both experiments, being determined by the same electrometer, was exactly the same.
Dr. VAN MARUM acknowleges that his rubbers are much more expensive than the common sort, and require greater care in their application and use; that the ttrong pressure of the rubbers, and the close adherence of the oiled lilk to the glass, render Rr 2