ese worked in pairs, and successively, in connection with
vibratory screens and sieving, all in one machine. By the action of this
arrangement the powder cake was broken into fragments, separated into
different sizes of grain, and each delivered into its proper receptacle.
A very large grained powder, each grain being a cube of one inch in
dimensions, and weighing about one ounce, was made by a separate
manipulation of the powder cake, and used for the very largest guns
only.

From the granulating building the powder was taken to the drying,
dusting and glazing department, 2500 feet further up the canal. There
was an intermediate building designed and used for several months, as
the dusting and glazing department, the drying alone being done in the
one above mentioned; afterwards the three processes were carried on
together in one structure. It was soon perceived that the drying
process, which was done by similar arrangements to those used at the
government works at Waltham Abbey, England, that is, by placing the
powder in small quantities in shallow trays in a frame work, over steam
heated pipes, required considerable manual labor and occupied much time.
It occurred to me that the same could be accomplished more speedily and
with far less labor, by a single operation, which would likewise perform
the glazing and dusting.

To accomplish this the powder from the granulating house was placed in
revolving cylinders having hollow axles, and a current of air warmed by
passing through an arrangement of steam pipes was blown through,
carrying the dust into its receptacle, leaving the grains clear. This
also dried and glazed them at the same time. Thus by one operation, by
machinery, all three processes were accomplished, resulting in a large
saving of labor and time. In addition, a beautiful jet black glazing was
given by admitting a small quantity of steam at the proper time to the
current of air, while the barrels revolved. This was not generally done,
however, as it was regarded of but slight, if any, practical value, the
usual glazing answering all required purposes.

Two hundred yards from this department was the boiler house supplying
the steam required for the pipes used in the drying process. Its chimney
was one hundred yards still further removed, communicating with the
furnace by a subterranean arched flue; thus sparks would have had to
drift over three hundred yards to reach the clean metal roof of the
drying bui