A Treatise on Magnetism; General and Terrestrial

A Treatise on Magnetism; General and Terrestrial

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1874 edition. Excerpt: ...purpose, it will be convenient to produce the equilibrium by turning the instrument in azimuth until the deflected needle is vertical; for, in this case, the deflecting magnet is horizontal, and can be placed in the usual position with respect to the deflected magnet without difficulty. For this purpose the apparatus is provided with a gun-metal bar, having a rectangular aperture, by means of which it passes over the box containing the deflected magnet, and rests on two supports fixed outside on the level of the agate planes. The deflecting magnet is to be placed on this support at different known distances, and on each side of the deflected magnet, its axis being in the plane in which the latter moves; and the apparatus is to be turned in azimuth until the deflected needle is vertical. In this case the general equation of equilibrium (96) becomes-X cos a = mil; in which U is of the form The quantities p and q are to be found in the usual manner, by repeating the observation at several known distances, and eliminating among the resulting equations. This being done, the deflecting magnet is to be removed from the bar, and placed in its ordinary position between the microscopes; and the observation is to be repeated. If a0 denote the corresponding azimuth, and U0 the value of U, -X cos eio = m Uo, whence cos a The method here proposed appears to offer the following advantages: --1. It is applicable with equal accuracy at all parts of the globe. 2. It dispenses with the employment of a separate instrument for the determination of the magnetic intensity, and with the separate adjustments required in placing it. 3. The constants to be determined--the magnitude of the added weight, and the radius of the pulley by which it acts--can be ascertained.show more

Product details

  • Paperback
  • 189 x 246 x 3mm | 127g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236970624
  • 9781236970626