ditional
outfits wherewith to equip more wagons and trucks. Edison expressed
his regrets, but said he was not satisfied with the old cells and was
engaged in improving them. To which the customers replied that THEY were
entirely satisfied and ready and willing to pay for more batteries of
the same kind; but Edison could not be moved from his determination,
although considerable pressure was at times brought to bear to sway his
decision.

Experiment was continued beyond the point of peradventure, and after
some new machinery had been built, the manufacture of the new type of
cell was begun in the early summer of 1909, and at the present writing
is being extended as fast as the necessary additional machinery can be
made. The product is shipped out as soon as it is completed.

The nickel flake, which is Edison's ingenious solution of the
conductivity problem, is of itself a most interesting product, intensely
practical in its application and fascinating in its manufacture. The
flake of nickel is obtained by electroplating upon a metallic cylinder
alternate layers of copper and nickel, one hundred of each, after which
the combined sheet is stripped from the cylinder. So thin are the layers
that this sheet is only about the thickness of a visiting-card, and yet
it is composed of two hundred layers of metal. The sheet is cut into
tiny squares, each about one-sixteenth of an inch, and these squares
are put into a bath where the copper is dissolved out. This releases
the layers of nickel, so that each of these small squares becomes one
hundred tiny sheets, or flakes, of pure metallic nickel, so thin that
when they are dried they will float in the air, like thistle-down.

In their application to the manufacture of batteries, the flakes are
used through the medium of a special machine, so arranged that small
charges of nickel hydrate and nickel flake are alternately fed into the
pockets intended for positives, and tamped down with a pressure equal
to about four tons per square inch. This insures complete and perfect
contact and consequent electrical conductivity throughout the entire
unit.

The development of the nickel flake contains in itself a history of
patient investigation, labor, and achievement, but we have not space for
it, nor for tracing the great work that has been done in developing
and perfecting the numerous other parts and adjuncts of this remarkable
battery. Suffice it to say that when Edison went boldly out