Fig. 7.
Fig. 8.
“A section of an induction coil made after this manner is shown in fig. 7, having a very strong effect. The primary wire, of which only a part is shown, is wound on an iron core, and outside is surrounded by an iron cylinder. Both of these are metallically connected by the flanges of the bobbin, which also are of iron. The secondary coil may also be surrounded by an iron tube, and if the resistance of the circuit be extraordinarily great with still more primary coils, or it may be also contained in the same tube as the primary. In cases where it is found necessary to increase the quantity of the electro-magnetic effects, we find that the forms shown in Figs. 8 and 9 are very effectual, and may by varied on the same principle. The iron core in the middle is wound with the primary wire, and is surrounded by the other iron cores, which are fixed into the large flanges of the middle core, and carry the secondary coils. Should still greater effects be required, more primary or secondary coils connected in series with the others may be added outside, in order to produce a greater extension of the poles and a more extensive induction.”
Fig. 9.
