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island, famous by its being the country of Hippocrates and Apelles, has at present scarcely any other recommendation to the attention of the curious.—Plates LX. LXI. & LXII, exhibit plans of the City and Ports of Rhodes, and a view of the tower of St. Nicholas in that city. Our Author's history of this island is learned and elegant, but it contains nothing that is very new.
II. Elemens de la Geometrie Souterreine Theoretique et Pračique, &c. i. e. Theoretical and Pračtical Elements of Subterraneous Geometry, as taught by M. KoeNIG, Direétor of the Mines of Lower Bretany, and extracted from the Metallurgical Voyages of M. JARs, Member of the Royal Academy of Sciences. 8vo. Paris. 1780. The application of the principles of ordinary geometry to the working of mines, is what the Author of this useful work calls subterraneous geometry; and the rules and dire&tions necessary to this application are clearly and concisely pointed out in these elements. In the first part of this Work the Author treats of metallic loads and veins; and in the second Part he describes the operations of subterraneous geometry in a masterly manner. Several of these operations are new, and happily conceived; and they are accompanied with plates, which exhibit various veins in a diversity of dire&tions, as also engravings of the instruments that are to be employed in subterraneous geometry. III. Lettre concernant la Chaleur du Globe, demontrée par Mess. de Mairan et de Buffon, &c. i. e. A Letter concerning the Heat of our Globe, demonstrated by Messrs. De Mairan and De Buffon, asserted by Mr. Bailli, and still existing, notwithstanding the Allegations of M. R. D. L. (by which letters we suppose is meant M. Romé De Lisle.) By M. L. So “*. Paris. 1780. Price I livre 1o sous. This Letter is an elaborate and ingenious treatise concerning one of the most curious obječts of modern enquiry and controversy. The hypothesis of a central fire, or a heat peculiar to the interior of the earth, that was so ingeniously maintained by M. de Mairan, and so romantically embellished by Messrs. de Buffon and Bailli, has met with warm and keen opponents; and here comes a conciliatory sage, with a plan of pacification, which exhibits new points of view to the combatants, is adapted to reconcile their jarring ideas, and designed to make them shake hands, and be friends:-The theory of our Author, which is intended to form the point of union between the contending parties, is founded on experiments (for every affirmer, in our days, must bring his vouchers, such as they are), and contains the following propositions:—that the air, being a mixt, susceptible of composition and decomposition, is not an element; – that nevertheless it is necessary to the action of fire, and also to the activity of the other elements;– and and that the heat which exists on the surface of our globe must be engendered in the air by the concurrence of the internal heat of the earth with that of the sun.—Our Author therefore distinguishes the pure air (or what he calls air principle), which is beyond the reach of our knowledge and experiments, from the mixed and compounded air we breathe, which is essential to vivification and vegetation,-peculiar to our earth, a part of its domain, a light covering, which preserves its inhabitants from the extremities of heat and cold, and a substance that is derived from its bosom, and nourished by its emanations. We refer the Reader to the Work itself for a detail of all the advantages that attend this new theory; the principal objećt of which is, to explain the rarefaction and condensation of the air, whose various properties are here particularly considered. His enquiry into the source and principle of heat, which ačts such an eminent part in the variations of this fluid, terminates in a theory that is subtile and ingenious, and accounts plaufibly for several phenomena, whose causes have not hitherto been sufficiently known : but the great question is, Is it true * True or not, his theory comes to this, that the solar rays, though they do not (as M. du Buffon supposes) produce heat by their frićtion against the parts of the aerial fluid, yet form combinations with certain parts of that fluid, which have an affinity to them ; and that a concentrated acid in these rays, uniting with the aqueous particles of the air, produces, as a primary cause, the heat, the principle of which some have sought for in the direct influence of the sun, and others in other causes. So that, according to this theory, the solar rays, if they did not meet with the aqueous particles of the air, would arrive at the earth without warmth or energy, as they do at the tops of the mountains. The conclusions and the explications of certain phenomena, which the Author deduces from this theory, and which will certainly be read with pleasure, are so satisfactory, that we should be glad to see the theory itself well established. IV. Reflexions fur l’Etat A:fuel de l'Agriculture, &c. Reflexions on the Present State of Agriculture; or an Exposition of the true Method of cultivating Lands to the greatest Advantage, without Manure. Paris. 8vo. 1780. This is the produćtion of a public-spirited member of society, who has applied himself early to the study of agriculture, and gives us, in this instructive Work, the result of long observation and expeTience. V. Histoire de l'Ordre Royal et Militaire de St. Louis. A History of the Royal and Military Order of St. Lewis. By M. Aspect, Historiographer of the Order. 3 Wols. 8vo. Paris. 1780.- This Work is good in its kind ; it contains G g 4 - enter