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 SAIEE VOLTAIC BATTERY. 93
its peculiar advantages. It is called a " constant'" or " sustaining " battery, from the regularity and duration of its
action. Mr. Simee denies the correctness of this name. FHe
says, " It is often thought to signify long-continued action,
whereas these properties are really different; for a battery
may be constant, but only remain in action for a a short
period; and, again, a battery might remain in action for
years, and not be constant in its action." Among practical
electricians, however, the Daniell battery is recognized as a
"constant battery," and as such it has been used in the local
circuits of many telegraph lines, with much economy and
satisfaction.
THE SMIEE VOLTAIC BATTERY.
The voltaic arrangement contrived by Mr. Smee deserves special notice from its general utility. The principal differences
between it and a battery of Dr. Babing- Fig. 15.
ton's arrangement consist in the material
of the conducting plate and in the mode |
of placing it. The conducting plate is
made of silver-foil platinized; that is, a
thin coat of platinum is deposited on the
silver by the electrotype process. The
minutely-divided particles of platinum
that thus cover and adhere to the silver,
present a greatly-enlarged surface to
liquid in which it is immersed, by which
means a smaller-sized plate answers
equally with a much larger one of smooth
metal. Platinum also being a metal less
readily oxydized than copper, the effect of i
the voltaic arrangement is heightened by
the greater dissimilarity of the two
metals. The platinized silver-foil is fixed
in the centrr sf a wooden frame s, and two zinc plates, z z, well
amalgamatecr, are attached to the upper rim of the fiame by a
brass clamp, which has a binding screw connected with it.
By this arrangement the zinc plates can be very readily removed and cleaned. In this respect a Smee's battery is more
convenient than any other; its action also approaches a Daniell's battery in constancy. These are important advantages,
which render this form of voltaic battery the best that can be
used for general purposes.
The substitution of graphite for the platinizocd silver plates