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. 1895 Excerpt: ... at the bottom (Fig. 80). The conductor is thus wound non-inductively. If it were wound round and round on the frame or on a cylinder, it would pro duce a magnetic field within it. The long brass screw at the top is traversed by a contact-maker. Instead of a nut this contains a screw pin, so that the contact-maker may ...
Read More
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. 1895 Excerpt: ... at the bottom (Fig. 80). The conductor is thus wound non-inductively. If it were wound round and round on the frame or on a cylinder, it would pro duce a magnetic field within it. The long brass screw at the top is traversed by a contact-maker. Instead of a nut this contains a screw pin, so that the contact-maker may slide readily from one end of the screw to the other by merely unscrewing the pin. When the pin is screwed in, the contact-maker may be moved slowly along the wires, so as to vary the portion in circuit, by turning the handle. If the constant of the electrodynamometer is to be determined, the instrument should be set up with the plane of its movable coil at right angles to the magnetic meridian, or with its magnetic axis in the earth's magnetic meridian, and variable currents should be avoided. As a check, it is desirable to employ two electrolytic cells in series. One-half the weight of the electrolyte or metal deposited in the two is then taken for use in the formula with either the silver or the copper voltameter. Example I. To find the Reduction Factor of a Tangent Galvanometer. The galvanometer was set up in series with a silver voltameter, two Daniell cells, and a commutator for reversing the current through the galvanometer. The coil used was marked 29.893 ohms. The current deposited silver for thirty minutes, and the deflections were read every minute, except when the current was reversed, when one reading was omitted. The observations were as follows: Mean 43.34 43.37 Mean deflection 43.36 Tangent of mean deflection 0.94435 Weight of cathode before deposit.... 30.3726 gms. Weight of cathode after deposit 30.4685" Gain 0.0959 Example II. To find the Constant of Siemens Electrodynamometer, No. 97 Q. Two copper voltameters were conn...
Read Less
