A Treatise on Telegraphy Volume 4; Prepared for Students of the International Correspondence Schools, Scranton, Pa (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. 1901 Excerpt: ... ergs are equivalent to 10,000,000 60 joules. From Art. 2333, 1 joule=.7373 foot-pound; then, 60 joules are equivalent to 60 X.7373 = 44.238 footpounds. Ans. (1187) From Art. 2400, B = )4-; where B = the magnetic density, /1 = the permeability of the magnetic substance, and H = the intensity of magnetomotive force. Substituting 180 for H and 450 for /4, B=450 180: 81,000. Ans. ELECTRICAL MEASUREMENTS. (QUESTIONS 1188-1229.) (1 188) The multiplying power of a shunt of 500 ohms resistance used with a galvanometer of 690 ohms resistance is (Art. 2488) Substituting the values of R, and R, given in this exam The current flowing through the galvanometer is, from formula 454, Substituting the values of C and n + 1 in the above for the current in the galvanometer when shunted. As a current of.06 ampere gives a deflection of 68 with this galvanometer, its constant may be calculated from formula 450, C: K tan m. Substituting the above values, For notice of the copyright, see page immediately following the title page. In this example, A =.1, I = 1, 1' = 12 cm. Substituting these values, 12 (11) In Washington, the value of the horizontal component of the earth's magi1etismHis.200. (Table 84.) Then, by formula 449, f: H tan 1n. Substituting the above values, f =.05236 and H =.200, (1 190) A controlling magnet serves to vary the action of the earth's field on the magnet of the galvanometer, by increasing or decreasing the strength of the earth's field at that point. (Art. 2466.) (1 191) The specific resistance of mica is 84 tregohms (Table 85); that is, the resistance between two opposite faces of a cube of mica, each edge being 1 cm. long, is 84 tregohms. 1 cm. =.3937 inch; therefore, the resistance of a piece of mica 4 inch long and 1 cm. square would be, c...