Transactions Volume 7 1889-1890

Transactions Volume 7 1889-1890

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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. 1890 edition. Excerpt: ... brand E were used. To secure uniformity in the plus and minus pencils, a 12 inch stick was broken in half, one portion being used as the upper, the other as the lower carbon. The length of each run was an hour. Current and potential were read every two minutes and the mean taken. Table 4 gives the data from which the curve for current and mortality (Fig. 3) was plotted. TABLE 4. Life With Different Currents And Constant Potential. As will be seen the range of current was from 6 to 13 amperes. The greatest variation of the mean E. M. F. for the several runs was one volt. TABLE 5. Life With Different Potentials And Constant Current. A series of tests was now made with constant current and varying voltage. The current in this case was maintained at ten amperes, and the range in tension was from forty to sixty volts. Carbons of the same type as in the last instance were used. In table 5, are given the figures for these runs and Fig. 14 shows the curve for voltage and mortality. In the curves (Figs. 13 and 14). the ordinates represent the life of an inch of carbon in minutes. Reference is made not to the mortality of the plus pencil, but to the total amount of carbon burned in the lamp. The last two columns in Table 5, have been corrected for diameter and resistance of the pencil, the diameter and resistance respectively of the carbon that was burned at 10 amperes and 45 volts having been taken as a standard, and the life of the other pencils reduced to a common basis from this, according to the law previously stated. Very little has been published regarding the relative life of the plus and minus carbons. Those books in which the subject is alluded to, state as a rule that with direct currents, the life of the upper carbon is about half that of more

Product details

  • Paperback | 184 pages
  • 189 x 246 x 10mm | 340g
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236653971
  • 9781236653970