canal, which were generally situated about one
thousand feet apart; thus the explosion of any one of them would be
harmless to the remainder. There was a temporary structure of wood used
at first for granulation, about one hundred yards distant from the
permanent building, on the opposite side of the canal; this, after a use
of some months, exploded with about three tons of gunpowder.

The explosion was heavy, shaking the earth for some distance, and
throwing up a convolving column of flame and white smoke five hundred
feet in height. It was composed of a series of confused masses of smoke
and heated air revolving in vertical planes with extraordinary velocity,
through which the flames flashed outwards in all directions; this was
followed by the thundering sound of the explosion, which vibrated the
air for a mile around, and was heard within the limits of the city.

There were seven men within the structure, a sentinel outside, and a boy
with a mule in a shed adjoining. The bodies of the seven men and the
boy, with the debris, were carried up with the ascending column, and by
its revolving action, reduced mainly to small fragments and dispersed;
the sentinel was killed by the shock, but his body was not otherwise
disturbed. A growth of small pines surrounded the place, which
effectually intercepted the lateral flying fragments; in fact the force
of the explosion did not extend outside a diameter of one hundred feet,
but within that area the trees were destroyed and the space where the
structure stood was ploughed up and nothing remained. At the time there
was no work being done, as the workmen were awaiting the arrival of the
boat with the mill cake. The careful foreman, Gibson, had been called
away, and probably the accident happened from matches falling on the
floor, as it had been found impossible to prevent their use by the
workmen, for smoking, when off duty. This was the only explosion at the
Works during the war, except the three at the Mills, already mentioned.
It demonstrated the safety of the arrangements, since there was no
damage to any portion of the Works except the destruction of the glass
sashes, and a slight movement of the roof of the permanent granulating
building, about one hundred yards distant. This was about to be
occupied, having been completed.

In the granulating building the cold mill cake was broken up into
fragments by bronze toothed cylinders of small diameter, and then by
smooth ones; th