. Annual report of the American Institute, of the City of New York. Science. 950 Transactions of the American Institute. Another test, made by putting two galvanometers (No. 18 and No. 9, coil 3) into same circuit, gave the following results: Galvanometer No. 18. Galvanometer No. 9. Ohms inserted. Mean deflection. Tangents. Mean deflection. Tangents. Quotients. 2 12 30 60 ° ° ° ° .5704 .2830 ° ° ° ° .8847 .3979 The near uniformity of these quotients gives evidence of very true tangent galvanometers. 12. The theorem,
. Annual report of the American Institute, of the City of New York. Science. 950 Transactions of the American Institute. Another test, made by putting two galvanometers (No. 18 and No. 9, coil 3) into same circuit, gave the following results: Galvanometer No. 18. Galvanometer No. 9. Ohms inserted. Mean deflection. Tangents. Mean deflection. Tangents. Quotients. 2 12 30 60 ° ° ° ° .5704 .2830 ° ° ° ° .8847 .3979 The near uniformity of these quotients gives evidence of very true tangent galvanometers. 12. The theorem, "The intensity of currents, as measured by the tangent galvanometer, is proportional to the tangents of the angles of deflection" may be verified in the following manner: Call the terrestrial magnetism,. whose tendency is to direct the gal- Ta^s manometer needle to the magnetic & meridian, the unit of directive force, and let this unit be represented geo- metrically by the line A M (Fig. 1), which is the radius of the circle M B M—the line MAM represent- ing the meridian. Now, let an elec- tric current be sent through the gal- vanometer coil whose directive force is precisely equal to the terrestrial force, and whose tendency is to direct the needle in a line perpendicular to the meridian, and let this force be represented by the A B. If the terrestrial force could now, for a moment, be suspended, the nee- dle would point due east and west, '^but the combined action of the two \M equal forces will direct the needle toward the point of intersection of the line drawn perpendicularly from M, and that drawn horizontally from B at 1, which direction cuts the quadrant at 45°, the line M 1 being the tangent of 45°, which is 1. Now, if we augment the intensity of the current through the coil. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrati
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