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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    Compound Horseshoe Magnet.—A magnet composed of several horseshoe magnets joined together, side by side, as in Fig. 4, for the purpose of in- creasing the power, is called a compound horseshoe magnet, or magnetic battery. These magnets are charged separately, and are put together with all the similar poles in the same direction. 9. Armature.—A piece of soft iron, adapted to, and intended to connect the poles of a magnet, is called an armature, or keeper. Horseshoe magnets are usually provided with an armature, consisting of a straight bar of iron, for the purpose of pre- serving their magnetic power: this should be kept constantly applied to the poles of the magnet when it is not in use; as shown in Fig. 4, where A is the keeper. Armatures are employed in various experi- ments, and their forms vary with the purposes intended. Fig 5. 10. Magnetic Needle. — A light and slender magnet, mounted upon a centre of motion, so as to allow it to traverse freely in certain direc- tions, is called a mag- netic needle. It may be so mounted as to move only horizontally, as in Fig. 5; or its motion