The telegraph manual: a complete history and description of the semaphoric, electric and magnetic telegraphs of Europe, Asia, Africa, and America, ancient and modern.

THE GROVE VOLTAIC BATTERY. 99
versal to place the batteries in boxes. There are Fig. 24.
many contrivances having in view the insulation
of the battery, to prevent local action, and cross
currents from one cell to the other, generating various circuits of quantity electricity. I haveseen
the batteries, set upon tables covered with a sheet
of gutta-percha, at other times I have seen the
cells placed on the flat surface of glass, or on the
edges of strips, cut an inch wide, and fastened in
saw grooves. The glass strips were placed an inch apart. This
Fig. 25.
was quite an effective insulation. The best arrangement for
insulating the cells, one fiom the other, has been gotten up by
Mr. J. H. Wade, of the Western Union lines. The Wade insulator is squared flat at the top, and it is set on wooden pins,
coated with gum lac, and fixed in the table. With this application there can be no cross currents, and the full voltaic force
of intensity can be thrown over the lines for the uses of telegraphing.
Fig. 26.
A rL^-__ B
Fig. 26 represents a sectional view of the Grove battery,
as practically employed on many lines, A is the platinum or
positive pole of the battery, and B the zinc or negative pole.
The chemicals act upon the zinc, and the platinum leads the
electrical force generated in the cell, to the next in course and
thence on. The current is indicated by the arrow, running
from the platina end to the zinc or negative pole of the battery;