Magnetical Investigations Volume 2 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1844 Excerpt: ...the observed torsions, viz., 9'4, 59, and 476, become, when reduced, 7'7, 59-0, 493-5, constituting the series 1, 77, 641--being a very close approximation to 1,8, 64, the series formed by the cubes of the lengths of the three magnets. The differences, indeed, are not greater than what may reasonably be attributed to the neglect of the equation of deviations and the errors of observation. Hence, it is clear that the deviating power of magnets of different lengths, affords, in the case of equal, or very nearly equal, deviations, a very practical and accurate mode of determining their magnetic powers respectively, --their powers being, in such case, proportional to the cubes of the lengths of the magnets. But the case under consideration, as stated in the outset, requires further investigation as to magnets of different lengths having unequal deviations. Combining the results, however, of case i., with the above of equal deviations, (case ii.), the rule becomes general under this simple expression: --P=Pt P being the actual directive power of the magnet, t the tangent of the deviation produced at a given distance, proportional to the length of the magnet, from the compass, and I the length of the bar. The verification of the rule by actual experiment will be abundantly yielded by the descriptions of the next case. Case III.--The Comparative Capacities for Magnetism of equivalent, or similarly proportioned, Bars of Steel of different lengths, as determined both by the method of Deviations and that of Torsion. This investigation involved other results. In addition to the object specially proposed for inquiry, --the required confirmation of the rule above stated was looked for. For if the ratios of powers of magnets of different lengths and unequal deviations as yi...