Scientific American Supplement, No. 315, January 14, 1882 by Various
page 35 of 143 (24%)
page 35 of 143 (24%)
![]() | ![]() |
|
stating that a result so high as 4,000 candles evolved for 40,000
foot-pounds absorbed has recently been obtained--an efficiency six or seven times greater than the record of six years ago. In accepting this statement we must not lose sight of the extreme probability that such effects were evolved under conditions rarely if ever found in common practice. Of course, I now refer to the arc system. The volume of light so generated is incomparably greater than by any other known method, though in subdivision the limit is sooner reached. Mr. Hawkesworth--Let me ask you a question, please. Supposing that it required a one-horse power to produce an arc light of, say, 2,000 candles, would it be possible to produce ten arc lights of 200 candles each? Mr. Daft--No, sir; I will tell you why. It would, if no other element than the simple resistance of the arcs opposed the passage of a current; then a machine that would produce an inch arc in one light, if placed on a circuit of sixteen lamps would give to each an arc one-sixteenth of an inch long naturally; but another difficulty here presents itself in the shape of a resisting impulse of considerable electromotive force in the opposite direction, apparently caused by the intense polarity of the two terminals. The resistance of the arc itself varies much according to the volume of current used being usually small with a large quantity of current, and greater with a current of tension; but this opposing element is always found, and appears to be the only real obstacle in the way of infinite subdivision. Almost every objection which human ingenuity could suggest has been urged against lighting by electricity, but fortunately electricians |
|