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Page 321 - ... the present we have used the fork above described only. It was chosen because it was fairly stiff, and as removable metal mirrors for the production of Lissajous' figures were attached to its prongs, it was possible to replace them by the glass mirror and square of wood without altering its pitch. It would be quite possible to use properly made forks of higher pitch as resonators, and the steadiness of the bands at night is so remarkable, that we believe that if the apparatus were set up in the...
Page 147 - As a unit of resistance, the international ohm, which is based upon the ohm equal to 10" units of resistance of the CGS system of electromagnetic units, and is represented by the resistance offered to an unvarying electric current by a column of mercury at the temperature of melting ice, 14.4521 grams in mass, of a constant cross-sectional area and of the length of 106.3 centimetres.
Page 147 - Ampere, which is one-tenth of the unit of current of the CGS system of electromagnetic units and which is represented sufficiently well for practical use by the unvarying current which, when passed through a solution of nitrate of silver in water, in accordance with a certain specification, deposits silver at the rate of 0.001118 of a gramme per second.
Page 136 - That gravity should be innate, inherent and essential to matter, so that one body may act upon another at a distance through a vacuum, without the mediation of any thing else, by and through which their action and force may be conveyed from one to another, is to me so great an absurdity, that I believe no man who has in philosophical matters a competent faculty of thinking, can ever fall into it.
Page 88 - Helmholtzt, on the basis of the formal equations of Heaviside and Hertz, in which the free aether is still supposed to be an elastic medium of excessively small density in which the dense atoms are imbedded. If such a view should turn out to be the basis of a consistent body of theory, the considerations given above with respect to the intensities of molecular tractions would have a bearing on it also. Let us now consider more particularly the explanation that would be offered by the electric theory...
Page 84 - There are about 1U3 molecules of the sensitive medium in the length of a single wave of light : thus in the stationary wavetrain all the parts of a single molecule would at any instant be moving with a sensibly uniform velocity, which...
Page 144 - I. The Object to be Attained. SOME time ago the authors considered the possibility of constructing an apparatus for the determination of the mechanical equivalent of heat which could be placed in the hands of junior students, and which would enable a sufficiently accurate result to be obtained without the introduction of troublesome corrections. For such a purpose the electrical method was naturally adopted ; for now that the commercial values of the electrical units are known with considerable accuracy...
Page 516 - The instrument described in this paper consists essentially of a photographic camera fitted inside with a magnetic needle, which carries a vertical transparent scale divided and numbered to 360°, and also with cross fibres which intersect at right angles. The fittings and adjustments of the instrument are of such a character that the camera can be accurately levelled and directed towards any point in a horizontal direction, and when a photograph is taken in an ordinary way the bearing of the median...
Page 87 - I~ 77) i an<l the phenomena of crystalline media could be included by assuming a vector-coefficient instead of the scalar a. The conclusion, then, is that in this limited range an elasticsolid theory of a very rare aether is not so much at fault as would at first sight appear. A theory based on difference of rigidity without difference of inertia, after...
Page 512 - Ampère seems to have considered that the oxidation at first alleged by Fresnel was caused by induction currents arising from the diurnal variations of the magnetism of the stationary magnet. But it is evident that the electromotive forces due to any such cause would be of an order of magnitude utterly inadequate for the purpose.