The circuit of the electro-magnet is made and broken by the vibration of the fork in different ways - say, by a wire bridge attached to the lower prong which dips into and lifts out of two mercury cups.
In a common form of electrically maintained fork, the fork is set horizontal with its prongs in a vertical plane, and a small electro-magnet is fixed between them.
By rot ting a small electro-magnet in water, between the poles of ano her magnet, and then measuring the heat developed in the wat r and other parts of the machine, the current induced in the coils, and the energy required to maintain rotation, he cal b lated that the quantity of heat capable of warming one you d of water one degree F.
Among the educational institutions are the Albany Medical College (1839) and the Albany Law School (1851), both incorporated since 1873 with the Union University, the Collegiate Department of which is at Schenectady; the Albany College of Pharmacy (1881), also part of Union University; the Albany Academy (1813), in which Joseph Henry, while a member of the faculty, perfected in 1826-1832 the electro-magnet and began his work on the electric telegraph; the Albany Academy for Girls, founded in 1814 as the Albany Female Academy (name changed in 1906); and a State Normal College (1890), with a Model School.
Two other courses of lectures were published in volume form, Dynamo-Electric Machinery (1882), and The Electro-magnet and Electromagnetic Mechanism (1891).
Soc., 1886, 40, 486), who in 1886 published an account of some experiments in which the relation of magnetization to magnetic field was deduced from observations of the force in grammes weight which just sufficed to tear asunder the two halves of a divided ring electro-magnet when known currents were passing through the coils.