" 3. The expanfion of permanent elaftic fluids is in geometrical progreffion to equal increments of temperature. 4. The refrigeration of bodies is in geometrical progreffion in equal increments of time. "A mercurial thermometer graduated according to this prin ciple will differ from the ordinary one with equidifferential fcale, by having its lower degrees fmaller and the upper ones larger; the mean between freezing and boiling water, or 122° on the new fcale, will be found about 1 10° on the old one. Mr. D. then adds a table exhibiting the numerical calculations illuftrative of the above-mentioned principles. In the fecond fection, which treats principally of the expanfious of liquids and folids by heat, a variety of facts, experiments, and appropriate remarks are contained, to which we would particularly direct the attention of the philofophical reader; but it is not in our power to give a clear, and, at the fame time, fuccinct account of the numerous particulars. We fhall only extract the refults of the experiments and calculations relative to the expanfions of liquids. The greatest denfity of water, as this author thinks, is not at 40°, according to other philofophers, but at or near the 36th degree of the old thermometer, or between 37° and 38° of that which he has propofed. The real expanfion of mercury from 82° to 212, he ftatcs at. Alcohol expands about of its bulk for 180, from -8° to 172°. Oil, and linfeed oil, expand about 8 per cent. by 180° of temperature. Oil of turpentine expands about 7 per cent. for 180°. Sulphuric acid, of the fpecific gravity 1,85, expands about 6 per cent. from 32° to 212o. Nitric acid, of the fpecific gravity 1,40, expands about 11 per cent. from 32° to 212°. Muriatic acid, of the specific gravity 1,137, expands about as much as the fulphuric acid. "Sulphuric ether," this author fays, "expands after the rate of 7 per cent. for 180° of temperature. I have only compared the expansion of this liquid with that of mercury from 60° to 90° In this interval it accords fo nearly with mercury, that I could perceive no fenfible difference in their rates. It is faid to freeze at 46°." Refpecting the expanfions of folids, Mr. Dalton contents himfelf with ftating the refults of the experiments of Smea ton, ton, Ellicot, and Borda; and laftly he adds a table exhibiting fome of the most remarkable effects which are produced at certain temperatures; fuch as the fufion of metals, the boiling of certain liquids, &c. In the fifth fection, which treats of the quantity of heat evolved by combuftion, this author, amongst other important particulars, defcribes a curious fimple apparatus for determining the quantity of heat extricated by the combuftion of inflammable elaftic fluids; but for the defcription of this apparatus, and likewife for the refults of the experiments that were made with it, we must refer our readers to the work felf. In the fequel of the fame section, the results of other experiments on the same subject are contained, together with fuitable remarks. The natural zero of temperature, or of the total privation of heat, forms the fubject of the fixth fection, wherein this author gives the hiftory of the various methods by which the determination of that point has been attempted. To each of those methods he adds his remarks, and the refult of his ex-. perience. The mean of all thofe refults fhows that the zero of temperature is about 6000° below the temperature of freezing water; and this, he says, we are authorized to admit until fomething more decifive is made to appear. The feventh fection contains an epitome of the results of Profeffor Leflie's important experiments on radiant heat, after which Mr. Dalton flates feveral experiments which gave him reafon to diffent, in a certain degree, from fome of Profeffor Leflie's conclufions. The eighth fection contains a particular examination of a well known fact refpecting the atmosphere; namely, that the atmosphere, in all places and feafons, is found to decrease in temperature according as we afcend, and nearly in an arithmetical progreffion. The question which Mr. Dalton endeavours to answer is, whence does this diminution of temperature arife? For this purpose, he, in the first place, ftates the common folution, which is, that the rays of the fun paffing through the atmosphere to the earth, heat the latter, and from the latter the heat is then communicated to the contiguous part of the atmosphere, whilft the fuperior ftrata receive leis heat in proportion as they are more remote from the furface of the earth. On examination, however, he finds that the latter part of this explanation is inadmiffible; for it is well known that heated air afcends with great rapidity; in confequence of which it should feein, that at greater diftances from the furface of the earth, the temperature ought to be R 3 higher higher and higher, contrary to obfervation, This, and other remarks, gradually induced him to reft the explanation upon the bafe of a new principle, which feems to be pretty fairly established by his fubfequent reafoning and illuftration. The principle is, That the natural equilibrium of heat in an atmosphere, is when each atom of air in the fame perpendicular column is poffeffed of the fame quantity of heat; and confequently, the natural equilibrium of heat in an atmofphere is when the temperature gradually diminishes in afcending." In the laft fection of the first chapter, Mr. D, attempts to explain the phenomena attendant on the congelation of water. He first ftates the phenomena, and then adds the principle. upon which he grounds his explanation; but it is not in our power to give a concife and fatisfactory idea of this explanation, efpecially for want of the figures to which he refers, and which are delineated in one of the plates which accom pany the work, The fecond chapter treats of the conflitution of bodies, and is divided into four fections; but the fecond of thofe fections is by far the longeft and the most elaborate of them all. Its title is, On the conftitution of mixed elaftic fluids. The phenomenon which this author endeavours to examine and to explain, was, as it seems, firft noticed by Dr. Prieffley, and it has, after Priestley, excited the wonder and the industry of many fucceeding philofophers, particularly of the author of the prefent work. The phenomenon is, that when elaftic fluids of different fpecific gravities (but whofe particles do not unite chemically upon mixture) are placed together in one veffel, they become uniformly dif fufed through each other without the leaft regard to their different gravities; whereas this is by no means the cafe with liquids. In explanation of this phenomenon, Mr. D. propofed an ingenious theory, which was announced to the world through various channels; but it met with confiderable oppofition, and several able writers publifhed their remarks upon it. Of thofe writers the principal are, Mr. Berthollet, Dr. Thomfon, Mr. Murray, Dr. Henry, and Mr. Gough. Now in the prefent publication, Mr. D. firft ftates his hypothefis, in the next place he confiders the objections which have been made to it by the above-mentioned authors, and lastly endea-." vours to modify his theory agreeably to the fuggeftions of his further experiments and more mature reflection. Mr. Dalton's hypothefis, in fhort, is, "That 247 "That the particles of one gas are not elaftic or repulfive in regard to the particles of another gas, but only to the particles of their own kind. Confequently, when a veffel contains a mixture of two fuch elaftic fluids, each acts independently upon the veffel, with its proper clafticity, juft as if the other were absent, whit no mutual action between the fluids themfelves is obferved." Mr. D. anfwers the objections which have been made to this hypothefis with propriety and acutenefs; cafting, at the fame time, confiderable light on the whole fubject of elastic and atmospheric fluids. The third chapter of this work is a very fhort one, for it occupies only five pages. It contains fome general and hypothetical ideas, principally relating to the primary particles of bodies, both fimple and compound. Thofe ideas are illuftrated by references to figures which are annexed, Upon the whole this work contains four copper-plate engravings, with proper explanations of the figures, &c. After a careful perufal of Mr. Dalton's prefent work, it must be acknowledged that his investigations, experiments, and obfervations, are generally directed towards the hypothetical and the fpeculative. The bufy world is juftly inclined to prefer what is practically useful, to the abftrufe inveftigations of theory or typothefis; yet it must be obferved, that in natural philofophy the practical part of a fubject is much promoted, and often directed into a regular channel, by the establishment of a rational, or even plaufible, theory; nor can fuch a theory be formed without a strict examination of facts, and the unreftrained difcullion of hypothefis. The well known facts relative to the fubjects of this work have been compiled, condensed, and expreffed by Mr. Dalton. in a clear and correct manner. To thofe he has added the accounts of other new facts. His hypothefes are free from any apparent abfurdity; and his anfwers to his various opponents are expreffed with moderation and propriety. We, therefore, hefitate not to recommend the careful perufal of this inftructive work to the philofophical world. ART. V. The Travels of Capts. Lewis and Clarke, from St. Louis, by Way of the Miffeuri and Columbia Rivers, to the Pacific Ocean; performed in the Years 1801, 1805, and 1806, by Order of the Government of the United States. Containing Delineations of the Manners, Cuftoms, Religion, &c. of the Indians, compiled from various authentic Sources, and qriginal R 4 original Documents, and a Summary of the ftatistical View of the Indian Nations, from the official Communication of Meriwether Lewis. Illuftrated with a Map of the Country inhabited by the Western Tribes of Indians. 8vo. 309 pp. 9s. Longman and Co. 1809. THIS volume records the fecond authentic and successful attempt to penetrate from various parts of the vaft continent of North America to the Pacific Ocean. The firft was by Alexander, now Sir Alexander, Mackenzie, who embarking from Fort Chepeywan, lat. 58 N. long. 110 W. from Greenwich, first explored the northern parts to nearly the 70th degree of latitude, and indeed till his progrefs was obftructed by the ice. Returning to Fort Chepeywan he afcended what is called Peace River to its fource, and from thence proceeded to the Pacific Ocean. For a detailed account of this arduous enterprize fee our twentieth volume, pp. 465 and 645, Two years fince we had a rude and unpolished, but certainly a very interefting account of the prefent undertaking, by Patrick Gafs, who was one of the perfons employed, probably, in fome inferior office in the expedition. Of this alfo we have given a fuccinct account *. The prefent volume is fanctioned by authority; and the wonder is, when we confider the abundant harvest of matter which the expedition muft neceffarily have exhibited; the new regions difcovered, new nations explored, fingular manners obferved, novelties in the animal and vegetable tribes, &c. &c. that the authors fhould be fatisfied with prefenting the refult of their adventures to the world in a fmall unembellifhed volume. It is indeed accompanied with a map of the country inhabited by the western tribes of Indians, between the Miffiffippi and the Pacific, but this is upon a very fmall fcale, and by no means the most fatisfactory. We are, however, thankful for it as it is, and have derived from it much entertainment as well as information, a part of which we fhall lay before our readers. In confequence of an order of Congrefs to explore the River Miffouri to its fource, a party were appointed, under the command of Meffrs, Lewis and Clarke, to enter that river at the point where it joins the Mifliflippi. In the interval between May 14 and Nov. 1, they had afcended no less than 1609 miles, where they took up their winter quarters among the tribe of Indians named the Mandans. The |