An Experimental Inquiry into the Nature and Propagation of Heat

Leslie Family

Leslie, Sir John

London: Printed for J. Mawman

1804

Harvard University

HathiTrust

In the public domain

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^L 6" AN EXPERIMENTAL Inaui THE NATURE, AND PROPAGATION, HE OF A BY JOHN LESLIE. LONDON: PRINTED FOR J. MAWMAN, NO. 22 POULTRY J SOLD ALSO BY BELL AND ERADFUTE, EDINBURGH. 1804. T. Gillct Printer, Salisbury Square. /& ; AND ILLUSTRATIONS. 52 1 Note XV. p. 133. The influence which the slow communication of impulse must have in heightening the effects casual disturbing force, receives illustration from the any through the atmosphere of of phenomena observed in narrow tides seas, where the waters to rise far above the height assigned are by theory. Compare, for example, the prodigious accumulation which takes place in the British Channel, with the moderate recipro cating swell that prevails in the free expanse of the Pacific Ocean. Straits and estuaries, by confining the current of influx, cause a derangement similar to what is produced by sympathy between the imperfect air, in augmenting If our the unequal the distant portions of the of that fluid. distribution globe had been smaller, the variations of the barometer would have been proportionally diminished. To investigate accurately, therefore, of wind, it is requisite to consider the motive acting simultaneously, progressive for the origin and effects diffusion. but as spreading themselves The problem will its complete solution, upon the extension partial differences ; a forces not as hence of with a depend, the method of discovery in the higher calculus to which it And though, in an aqueous medium, the ac tual motion is much slower and the propagation of impulse swifter, the currents of the ocean must likewise experience a first gave rise. certain degree of modification. The profound researches of on that subject would consequently require some Laplace revision. Note XVI. p. 136. Mr. Hume is the first, as far as 1 know, who has treated of causation in a truly philosophic manner. sary Connexion seems a model His Essay on Neces of clear and accurate reasoning. But ; KOTES 5*8 But it was only wanted to dispel the cloud had long darkened so of mystery which that important subject. The unsophis ticated sentiments of mankind are in perfect unison with the deductions of logic, and imply nothing more at bottom, in the relation of cause and effect, than a This will distinctly quence. appear constant and invariable from a critical se examina tion of language, that great and durable monument of human Etymology has indeed been often exposed to ridi cule, by the crude and fanciful opinions of philologists and thought. dreaming Yet therefore to cover it with un antiquaries. To trace qualified contempt, would only betray ignorance. etymologies with sober light of philosophy, circumspection, and guided by the of ingenuity, is not only a liberal exercise but elucidates finely the various phases of the human mind, and represents to our view the history and progress of its Derivations are not safely inferred more abstruse operations. from solitary instances ; they must be drawn from the com parison of whole classes of words, and the uniform analogy of different languages. It would be foreign to my present ob I trust, however, that the ject to engage in such discussions. few examples which I shall select will amply confirm what has been advanced. appropriate term for cause. The same word, with only slight alterations, runs through Ursach, in German, of the several branches of ur, noun. is the an inseparable It the Gothic stem. preposition, Sache denotes a thing of and is compounded sache, a substantive moment, an interesting and im ur, signifies before or anterior. It now occurs only in composition, but its radical force is there portant object. The prefix, clearly marked. to designate the By the German mineralogists, it supposed trap and Ur-kalkstein Uranfangliche Gcbirgsarten. The same the employed Thus, Urgeneral class of primitive substances —comprehended under is : particle had passed into other dialects, and is even retained in English, though now very seldom used except by the poets — " Ere the mountains were