Report of the Annual Meeting Volume 64, PT. 1894

Report of the Annual Meeting Volume 64, PT. 1894

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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. 1894 edition. Excerpt: ...adjusting the edg! to the ordinate, and the zero to the zero of the scale. Set a needle at the extremitJ of the ordinate; bring a straight edge to touch the needle and the cam; prick o a point at the intersection of the straight edge with the other edge of the frame This point determines the length of the new ordinate. An instrument provided with a logarithmic cam was eKhihited. With thi instrument the product or quotient of two curves can he found by adding or sub trading the logarithms of the ordinates; or the logarithms of a series of observa tions can be plotted. Cams for other functions can be easily made; but it must 1 Printed in extenso in the Electrician, August 17, 1894, vol. xxxiii. p. 4G5. remembered that the action of tbe instrument is, as it were, arithmetical rather than geometrical, for a cam is useful only with reference to its own scale. This instrument not only enables transformations of a definite and known character to be made, but is equally applicable for transforming in an empirical manner. The curve drawn by a recording voltmeter or ammeter may thus be replotted for estimation of area, or other graphical analysis, without any knowledge of the law of the particular instrument. In other words, a correction can bo applied to a curve. The cams are easy to make, and even if carelessly cut cannot possibly give rise to cumulative errors. It is convenient to use the upper edge of the ruler instead of the edge which rolls on the cam. The curve must in this case be set out with the ruler, and used with the same ruler, or one of the same width. The rolling of a straight edge on a cam has been used in a photometer, invented by Mr. W. H. Preece and the author,1 for the automatic calculation of the squares of the displacements...
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Product details

  • Paperback | 502 pages
  • 189 x 246 x 26mm | 889g
  • United States
  • English
  • black & white illustrations
  • 1236845919
  • 9781236845917