Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity.

  • Davis, Daniel.
Date:
1854
Catalogue details

Licence: Public Domain Mark

Credit: Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity. Source: Wellcome Collection.

Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.

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    PRODUCTION OF ELECTRICITY. 13. As a current of electricity is requisite in many of the experiments to be mentioned here- after, it becomes necessary to describe the various means by which it may be produced, I. MECHANICAL OR FRICTIONAL ELECTRICITr. 13. The electricity developed by the electrical machine is called mechanical or frictional, from the mechanical force or friction by which it is obtained. It possesses properties differing much in degree from those exhibited by the galvanic arrangements de- scribed below, and is far inferior in producing mag- netic effects, which require an electric current. On the other hand, it greatly surpasses galvanic elec- tricity in exhibiting the phenomena of electricity at rest, under its two forms of positive and negative, 14. The great development of electricity observed daring the escape of steam from high pressure boil- ers, may be mentioned here. This is collected for purposes of experiment, by plunging into the steam, escaping from the safety valve, a brass rod (Fig, 7)