For the uninitiated, a hot shot furnace existed to heat solid shot to a condition of red-hotness, whereupon that projectile would be (carefully!) loaded into a nearby gun and fired into the timbers of an attacking wooden sailing ship, plunging it instantly into a state of unquenchable flame. That historically this belabored practice never really worked all that effectively was lost on the starfort builders of the early United States, who included at least one such furnace at just about every seacoast fortification on America's shores. Click here to see how a hot shot furnace works, as illustrated by a nearby sign.