Unbound: How Eight Technologies Made Us Human and Brought Our World to the Brink

by Richard L. Currier

The problem with all of the early firearms was in their method of manufacture. The barrels of the early guns and cannons were created by casting molten bronze or iron in molds, but the process of casting molten metal does not produce a smooth or precisely straight barrel, and small irregularities inside the barrel would affect the trajectory of the projectile. In addition, the early firearms lacked the “rifling” that is incorporated into all modern firearms. Rifling consists of spiral grooves that cause the projectile to begin spinning as it travels down the length of the barrel, which greatly straightens the trajectory of the bullet, immensely increasing the range and accuracy of the weapon. But the technology of precision machining made it possible to bore the barrel of a firearm into a precisely smooth, straight tube, and it was this development, more than any other, that gave the firearm its deadly effectiveness and that finally rendered obsolete the swords, spears, and arrows of earlier times. This is why, when James Watt needed to build a precisely fitting piston and cylinder for his new steam engine, he turned for a solution to John Wilkinson, a cannon maker.