Around 1670, a young man from Devonshire in western Britain joined the Royal Navy. By regulation, he was to spend the rest of his adult life at sea. In that sense, he must have enlisted "voluntarily."
Those who enlisted voluntarily enjoyed certain financial advantages: the Navy paid them two months' wages in advance. By custom, however, new recruits had to use part of that money to buy their equipment, including the hammock they slept in aboard ship. Moreover, if a volunteer recruit owed less than twenty pounds sterling, that debt could be forgiven.
"Load the powder!" the officer commanded. The young man and the other powder handlers poured gunpowder into the barrel and fed it into the firing chamber.
The powder was usually wrapped in ordinary paper cartridges. Then the cannonball was loaded and seated against the powder charge. Above the firing chamber was a small tube leading up to the top of the cannon, ending in a small opening: the vent. A fuse ran from the vent down into the firing chamber. In normal operation, the gunner lit the fuse, which ignited the powder, concentrating the immense energy in the firing chamber. The chamber was made of reinforcing material cast from a sturdy iron-carbon alloy, with only one exit. Nearly all the energy produced by the explosion was released through the barrel, propelling the cannonball outward.
The cannon was simple and effective, which was why its basic design and operation remained in use for centuries.
Although cast iron possessed a highly durable crystal structure, its strength could sometimes plummet because of impurities invisible to the naked eye, especially when the iron-carbon ratio had not been properly controlled. This could easily lead to serious accidents. For example, if the reinforcing material produced by a blast furnace contained flaws, and the