Accidents from the electric current : a contribution to the study of the action of currents of high potential upon the human organism / by Philip Coombs Knapp.

  • Knapp, Philip Coombs.
Date:
1890
Catalogue details

Licence: Public Domain Mark

Credit: Accidents from the electric current : a contribution to the study of the action of currents of high potential upon the human organism / by Philip Coombs Knapp. Source: Wellcome Collection.

Provider: This material has been provided by King’s College London. The original may be consulted at King’s College London.

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    Blaserna,81 who found that the extra current of open- ing was of shorter duration, but much more intense than the extra current of closing. Now every dynamo current necessarily contains a coil in its circuit, and consequently must present the phenomena of induct- ance. Hence, when a person receives a shock from a dynamo-current, he must also get when the current is broken, a self-induced or extra current of opening, of great intensity, but short duration. The strength of this extra current depends on so many factors that it is not easy to calculate, but I understand that, with a current of 500 volts, it may reach 2,000 or 3,000 volts. It follows, then, that where the factors in the prob- lem are so variable, we cannot make any positive asser- tions, and say that because A received a shock from a 2,000-volt current, without harm, it must be harm- less to B, when we known neither the body-resistance of A or B, nor what part of the current A received. As well say that, because A swallows ten grains of morphine and survives, ten grains is a safe dose to give to B. Bearing all this in mind, we may note the very few data which we possess, in the hope of getting some little empirical knowledge. The currents of high potential to which we are ex- posed are the continuous and the alternating: the for- mer being the one now in use in Boston for the electric cars and the electric lights. The voltage of the trolley-current is claimed to be 500, although this is probably often exceeded. The voltage of the arc light is about 2.000 to 3,000. As regards the trolley-current we have seen (Case VII) that it may produce serious injury. I learn that the horse recently killed by electricity in Cam- bridge made a ground circuit with a trolley-wire, and at « Blaserna: Glornale Ui soieuze natural i ed eoonomicke. vi. 22. 1870.
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