Fig. 278.—Gramme Machine, with Eight Vertical Electro-magnets.
Fig. 279.—Gramme Machine, with Horizontal Electro-magnets.
Fig. [278] represents one of the light-producing machines. The electro-magnets are excited by a portion of the currents they themselves produce, they retaining sufficient residual magnetism to develop the currents. There is a pair of current-collectors on each side. This machine weighs 1,540 lbs., its height is 3 ft., and width 2 ft. It will produce a light having the intensity of 500 Carcel lamps, which may be doubled by increasing the speed. Fig. [279] is another form which is also adapted for illuminating purposes, and, when made with fewer coils, for electrotyping purposes also. There are in this also two sets of current-collectors, and by means of a connecting cylinder (seen at the base of the machine) the currents can be combined for quantity and for tension as may be required. This machine is only about 2 ft. square, and it produces a light equal to 200 burners; but this may be increased, as the following table shows:
| Number of revolutions per minute. | Intensity of light in Carcel Lamps. | Remarks. |
|---|---|---|
| 650 | 77 | No heating and no sparks. |
| 850 | 125 | No heating and no sparks. |
| 880 | 150 | No heating and no sparks. |
| 900 | 200 | No heating and no sparks. |
| 935 | 250 | A little heat, no sparks. |
| 1,025 | 290 | Heat and sparks. |
The value of M. Gramme’s invention for electro-plating is proved by the fact of its adoption by Messrs. Christofle of Paris, whose electro-plating establishment is one of the largest in the world. This firm has no fewer than fourteen of these machines at work, and each is capable of depositing 74 ozs. of silver per hour. There is little doubt that the electric current will now soon be employed for reducing metals. Thus fine copper, which is worth 3s. or 4s. per lb., may perhaps be obtained at about the cost of ordinary copper; potassium, sodium, and aluminium at less than half their present price; and magnesium, calcium, and other rare metals at prices which will bring them into commercial use. The machine shown in Fig. [280] is intended for electro-plating and for general purposes: it supplies the means of readily and cheaply plating with copper, or with any other metal, such articles as steam pipes, boiler tubes, ship plates, guns, bolts, nails, marine engines, machinery, culinary vessels, cisterns, &c. The advantage of protecting iron or other material from corroding agents is obvious; and as iron coated with copper is available not only for useful, but also for artistic, purposes, as a cheap substitute for bronze, this invention will doubtless lead to a greatly extended application of bronzed iron in buildings and ornamental structures.
The machine well illustrates how mechanical work may be changed into electricity, and electricity caused to do work. The power required to drive the machine at a given speed is much less when no current is being drawn from it, than when the current is flowing. If the current from one machine is sent through the armature of another, the latter revolves, and may be made to do work. Thus power may be conveyed to a distance by electricity, with only the loss caused by the resistance of the conducting wires. If, when two machines are thus connected, the direction of rotation in the first one be suddenly reversed, the armature of the second will almost immediately stop, and then resume its motion in the opposite direction. A very interesting experiment can be performed when the circuit connecting the two machines is made to include a certain length of platinum wire. When both machines are in motion, the platinum exhibits no heating effects; but if the second machine be stopped by an assistant while the rotation of the first is continued, the wire is raised to a red heat. In this way it is shown that motion, electricity, and heat are related to each other, and are mutually convertible; for on the stopping of the second machine, the electricity being no longer used up, so to speak, in producing motion, has its power transformed into heat.
The Gramme machine has also been ingeniously employed for railway brakes on some of the Belgian lines; and it is applicable to telegraphy, where the cost of zinc, acids, batteries, &c., is a considerable item. It is impossible to predict the many applications for manufacturing purposes which will be made of electricity, now a cheap, reliable, and convenient mode has been discovered of producing currents of any required strength. Though by no means the first or only machine by which mechanical force can be converted into dynamical electricity, it shows an immense advance on any former one in the regularity of the action, and in the capability of being driven at a very high rate of speed without the inconvenient accompaniments of the heating of the conductors and destructive sparks at the movable contacts. There can be no doubt of the importance of this machine for use in lighthouses, and for metallurgical and chemical purposes, and the inventor believes the time will come when all large ocean-going vessels will carry an electric light at the masthead. The light would be sufficiently powerful to show rocks or land five or six miles ahead, and an additional safeguard of incalculable value would be thus provided for those “that go down to the sea in ships, that do business in great waters.”
