Descriptive catalogue of magnetic, electro-magnetic, electro-dynamic, and magneto-electric inductive instruments and apparatus : constructed and sold by Watkins and Hill, 5 Charing Cross, London.

  • Watkins and Hill.
Date:
[between 1837 and 1851]
Catalogue details

Licence: Public Domain Mark

Credit: Descriptive catalogue of magnetic, electro-magnetic, electro-dynamic, and magneto-electric inductive instruments and apparatus : constructed and sold by Watkins and Hill, 5 Charing Cross, London. Source: Wellcome Collection.

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    of the bar at the proper period, attraction being then changed to repulsion : the revolu¬ tion of the bar is continuous, 12s., 15s. 98. Ritchie’s straight bar electro-magnet, to rotate between the poles of the permanent steel horse-shoe magnet; divided mercury chamber and mahogany standard, 7s. 6d. 99. Henry’s Apparatus to illustrate reciprocating motion, produced by magnetic attraction and repulsion. It consists of a horizontal electro-magnetic beam poised upon a central axis, with two permanent magnets placed vertically, one under each pole; by a contrivance provided the polarity of the electro-magnet is made and reversed at proper periods, so as to produce vibrations in the beam, £2 2s., £2 12s. 6d. 100. Electro-Magnetic motive Model, consisting of vertical permanent steel magnets and hori¬ zontal soft iron electro-magnets, with contrivances on the main spindle for reversing the directions of the currents, and thus to produce rotatory motion by the electric and mag¬ netic forces, £6 6s., £8 8s., £10 10s. 101. Electro-Magnetic motive Model, consisting of two soft iron electro-magnets and four bent permanent steel magnets attached to a horizontal moveable axis, supported on a hollow wooden column. The arrangement for changing the direction of the current cannot be shown, but it so affects the order of polarity in the soft iron magnets at the right period, that the continued revolution of the permanent steel magnets is produced, £2 2s. 102. Electro-Magnetic motive Model, consisting of a bent permanent magnet, with straight bar electro-magnets attached to a main horizontal spindle, which also carries the battery contact breaker. The advantage proposed in this form of model is that no repulsion takes place, but that the motive power is due to the sum of the attractions, and not the dif¬ ference, as in many other combinations, £3 13s. 6d. 103. Electro-Magneto motive Model, in which a stationary horizontal compound permanent steel magnet is employed, and revolving electro-magnets, with the necessary contact breaker arranged that no repulsion occurs, the motive power being the sum of the at¬ tractions, and not the difference, £16 16s. 104. Electro-Magnetic Pendulum, with soft iron ball suspended from a cross piece at the top of the vertical standard. A contrivance lets on and cuts off the electric current in the electro-magnets, so as to produce at the extremities of the pendulum oscillations, the requisite alternate attractions by which means the vibrations are continued as long a time as the voltaic action is maintained, £5 5s., £9 9s. 105. Electro-Magnetic Verge, consisting of a horizontal helical spring, balance, and pallet, which being actuated by the alternate attraction of a small electro-magnet, produces