Originally, musket balls, grape shot, and other smallish round projectiles were produced in molds. This was slow work and more often than not resulted in flawed, uneven shot that was not particularly reliable and could even be dangerous. So a better way of creating shot would be an important invention.
About the same time Britain was pulling the last of her forces out of the newly independent United States, and a few years shy of Britain heading for and claiming Australia, a British plumber named William Watts was watching dripping water, and he noticed that the water droplets became perfectly spherical as they fell through the air. He ran home, added a few more stories to one side of his house, and started experimenting with trying the whole spherical drop concept using molten lead. It worked. The liquid lead became spherical while falling and hardened into that shape when it hit the bucket of water Watts had waiting for it at the bottom of the tower. By using different sizes of colander, he could produce different sizes of drips and therefore of shot. And so was born the shot tower.
The Industrial Revolution had been in full swing for some time, and people had gotten accustomed to happily hopping on the latest invention, and shot towers were no exception.
When Thomas Jefferson got Congress to pass the Embargo Act in 1807, with the hope that it would keep Britain and France from hurting U.S. shipping, it spelled the end of importing British shot. The first shot tower built in the U.S. was the Sparks Shot Tower in Philadelphia, which was completed in 1808. In this tower, tons of ammunition was produced during the War of 1812 and the Civil War. The Sparks Shot Tower was actually in operation until 1903.
The first shot tower built in Australia was the one I saw along the banks of the Derwent River, just outside of Hobart. It is a remarkably handsome shot tower, and is the tallest in the Southern Hemisphere. An enterprising Scot named Joseph Moir constructed it almost single-handedly, completing it in 8 months and dropping his first shot in September 1870. Moir’s factory produced shot for contemporary muzzle-loading sports guns. Moir died four years after his tower was completed, but his sons took it over, and it continued to operate for 35 years.
The tower is actually more impressive than you might guess from the photo below. Constructed of more than 8,000 individually curved and tapered sandstone blocks, it is more than 30 feet across at the base. The internal spiral staircase of more than 300 steps allows for enough space in the center of the tower to accommodate the falling lead droplets, and the tower is surmounted by a room that offered enough space to comfortably process the lead, and which now affords visitors stunning views of the surrounding countryside.