Report on the scientific results of the voyage of during the years 1873-76 : under the command of Captain George SNares, , Captain Frank Turle Thomson, . Regnaults apparatus,gave as the compressibility of mercury 0-00000295which Amaury and Descamps afterwards reduced to 0-00000187,the master himself had previously assigned the value 0-00000352. Had Grassis result been correct, I should have got only about half the displacementsobserved; had that of Amaury and Descamps been correct, the apparent compres-sibility would have had the opposite sign to that I obtain
Report on the scientific results of the voyage of during the years 1873-76 : under the command of Captain George SNares, , Captain Frank Turle Thomson, . Regnaults apparatus,gave as the compressibility of mercury 0-00000295which Amaury and Descamps afterwards reduced to 0-00000187,the master himself had previously assigned the value 0-00000352. Had Grassis result been correct, I should have got only about half the displacementsobserved; had that of Amaury and Descamps been correct, the apparent compres-sibility would have had the opposite sign to that I obtained, so that the index wouldnot have been displaced. In such a case the construction of the instrument mighthave been much simplified, for the index would have been placed in contact with themercury at B, and the bent part of the tube would have been unnecessary. 1 Relation des Experiences, &c, Mem. Acad. Sci. Paris, torn. xxi. p. 461, 1847. 20 THE VOYAGE OF CHALLENGER. IV. Amagats Manometre a Pistons libres. The annexed sketch of the instrument (in which the large divisions shown on themanometric scale correspond to decimetres), with the section given below, will enable. the reader to understand its size and construction without any detailed descriptionbeyond what is given in the instructions for setting it up. [The window FF, whoseposition is nearly immaterial, occupies different positions in the. sketch and in thesection.] As already stated, the principle on which this instrument works is the same asthat of the Manometre Desgoffes, a sort of inverse of that of the well-known BramahPress. In the British instrument pistons of very different sectional area are subjected PHYSICAL PROPERTIES OF WATER, ETC. 21 to the same pressure (that of one mass of liquid), and the total thrust on each is, ofcourse, proportional to its section. In the French instrument the pistons are subjectedto equal total thrusts, being exposed respectively to fluid pressures which are inverselyproport
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectscientificexpedition
