Throwing Fire

by Alfred W. Crosby

October 4th, 2008

This short book (199 pages long) recites the basic history of human use of projectiles. It starts with the rock-throwing early hominids. We used rocks to do what other animals did with tooth and claw -- which had the advantage of permitting us to kill at a distance. This trick, however, demanded a great many neurons to get the timing perfect. In throwing a rock at a rabbit four meters away, you must release the rock in an 11 millisecond launch window; at eight meters, the launch window narrows to just 1.4 milliseconds. If you know anything about the vagaries of neuronal transmission, you'll instantly realize that this is simply not possible with a single neuron. However, if you bundle hundreds or thousands of neurons together to handle the task, then the statistical combination of their errors will combine to produce the kind of timing accuracy needed to hit the target.

From that point forward humans continually advanced the power, accuracy, and lethality of their rock-throwing. They replaced rocks with spears, which do more damage due to their penetration power. However, the spears had a problem: because they were lighter than rocks, they couldn't be given as much kinetic energy as big rocks. The solution to this problem was the atlatl or throwing stick. By throwing a spear with a throwing stick, men extended the effective lengths of their throwing arms, which gave the spears higher velocities so that the total kinetic energy of the spears was limited only by the strength of the thrower.

Next came bows and arrows. Initially these were made of wood, but wood doesn't store much energy before it breaks. The solution was the compound bow: a composite of strips of animal horn interleaved with strips of wood, and the whole thing varnished together. This kind of bow could store a lot of energy, thereby making it more powerful. The bow underwent continuous if slow development. The Chinese made a breakthrough when they came up with the crossbow as a means of giving even more power to the bow. By adding a stock and catch mechanism, they enabled the archer to use his back muscles rather than his arm muscles to stretch the bowstring. This meant that the bow could be packed with enormous amounts of energy, so much that wooden arrows were simply to light to carry that energy -- more massive metal bolts were required to get the best advantage of this new technology. Together, the crossbow and the longbow remained superior to firearms for more than a century after the invention of guns.

But gunpowder provided the next huge leap in projectile technology. The Chinese invented it but it took the constant warfare of Europeans to develop the technology to its lethal acme. At first the only function of firearms was as cannon to knock down castle walls. This itself had a revolutionary impact on history -- it forever ended the ability of feudal lords to hole up in their castles and defy the kings. It also made cities more vulnerable: Byzantium was conquered in 1453 by cannons so large that they had to be cast and built on the battlefield.

Europeans loved their guns, and for the next 500 years they kept refining them. They made guns smaller and smaller, building small cannons, then muskets, and finally pistols. They made gunpowder ever more powerful, permitting armies to carry enough powder to fight long wars. They improved the manufacturing processes for weaponry, and then with rifling (putting spiral grooves in the barrel to make the bullet spin), made guns more accurate. The process continues today: the latest developments in gun technologies include guns that can fire an astounding number of rounds per second and cannons that fire "depleted uranium" rounds. Why depleted uranium? Because it's denser than lead, so packs a heavier punch. The nuclear properties of uranium are irrelevant to their value as ammunition for tanks. They're expensive enough, however, that their use is restricted to tanks, which need to pack a big punch to break through the thick armor of their opponents.

And now we come to the final stage of projectile technology: rocketry. Once again, it was the Chinese who invented the technology, but it was the Europeans who made it lethal. Armies started using rockets for signaling purposes in the late 18th century. They also tried them out as weapons, but found them of little value other than to scare the enemy -- which only worked once. It was World War II Germany that built the first ballistic missiles, and it used these to pound England. Over 4,000 V-2s were launched; 25% failed in the air. A thousand V-2s hit England; they injured 6,000 people and killed 3,000. The slave laborers who manufactured the V-2s for Germany suffered more deaths (20,000) than the intended victims.