Medical electricity / By H. L. Jones ... Being the third edition of Medical Electricity, by W. E. Steavenson, M.D., and H. L. Jones, etc.

  • Steavenson, W. E. (William Edward), 1850-1891.
Date:
1900
Catalogue details

Licence: In copyright

Credit: Medical electricity / By H. L. Jones ... Being the third edition of Medical Electricity, by W. E. Steavenson, M.D., and H. L. Jones, etc. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

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    city between it and another conductor. In the former case the body is said to be electrified by conduction, in the latter by induction or inductively. Take a hollow metal vessel, insulate it by hanging it up by silk threads, and connect it with an electroscope.* If the vessel be unelectrified and we introduce into it an electrified body, taking care not to touch the sides of the vessel so that no charge passes from the electrified body to the vessel, the electroscope will indicate a charge, and on being tested it is found to be a charge of the same sign as that on the charged body introduced into the vessel, e.g., if the charged body is a piece of rubbed glass, the electroscope will indicate positive electricity. If now it be removed without having touched the interior of the vessel, the leaves of the electroscope will collapse, and the vessel will be left without charge, if, however, it has been allowed to touch the vessel, the leaves will remain divergent, but the body will be found to be completely discharged. In the first case the vessel is said to be electrified by induction, and from the second case we see that the observed induced electrification is exactly equal to, and is of the same sign as that of the inducing body. Had we momentarily connected the vessel to earth so as to discharge the first induced electrification, and then removed the charged body without touching the vessel, the vessel would be found to be charged -with the oppo- site kind of electricity to as great an extent as in the first case. Similar effects are produced whenever an electrified body is brought near any other body, and this is what was referred to in § 6, when it was stated that the light bodies apparently attracted by an electri- * Faraday's Experimental Researches on Static Electrical Induc- tive Action. Maxwell's Electricity and Magnetism, vol. i., p. 32.