HOT SHOT OVEN AT FORT MARION
The substantial little furnace for heating cannon balls on the seaward side
of Fort Marion (Castillo De San Marcus) has been an object of interest since its
erection in 1843. These auxiliaries of the artillery have been common to forts
erected on the seacoast since revolutionary times, and the shot heated in these
ovens were very effective against wooden ships.
The hot shot furnaces were all about the same size and held 60 or more
shot, according to the caliber. The shot being placed in the furnace cold, it
required one hour and fifteen minutes to heat them to a red heat, but once the
furnace was hot, a 24-pounder shot could be brought to red heat in 25 minutes;
the 32 and 42-pounders requiring a few minutes longer. An unusual circumstance
concerning the heating was that the balls expanded under the heat but did not
return to their normal size after cooling.
Once the balls were cherry-red or white hot, they were taken from the
furnace with iron forks, scraped carefully with rasp to remove scale, and carried in
ladles to the cannon. The ladles were formed of an iron ring, the interior of which
was beveled to fit the ball, with two wooden-handled arms inserted.
Several other implements were attached to the furnace also; pokers for
stirring the fire, rasps, tongs with circular jaws for taking up shot, iron rake to
remove cinders from ash pit, tub for cooling implements, rammer with head
covered by a circular plate of sheet iron of