American Rifle - Alexander Rose [50]
Forsyth’s withdrawal left a vacuum that others were all too willing to fill, and his rivals focused on making priming more convenient. At least four inventors—Joseph Manton, John Day, and Joseph Egg, all of England, as well as a recent English immigrant to Philadelphia, Joshua Shaw—laid claim to the idea of filling with fulminate a small copper “nipple” that would be detonated by a hammer striking it. Hence “percussion caps,” their rather less powerful descendant being the caps used in children’s toy guns. Perhaps Shaw should properly be called the percussion cap’s father: he originally applied for the patent in 1814, but it was rejected on the grounds that he had lived in the United States for not long enough to qualify for patent protection. In 1815 he began using pewter caps before switching to copper ones a year later. His story had a happy(ish) ending, something of a rarity in the history of gun development. In 1846, following a lengthy investigation, the American government awarded him $25,000 (about $635,000) for what it called “one of the most ingenious, and one of the most useful inventions in modern terms.” (It was so ingenious and useful that Washington later reduced its prize to $18,000.)62
Forty years later Shaw’s caps were still being used, though Edward Maynard, a Washington, D.C., dentist and former gun designer, eased the process by developing the “Maynard tape primer” in 1845. Shaw’s caps each had to be inserted individually, whereas Maynard’s adaptation consisted of a roll of fifty caps encased between two strips of varnished paper. (Again, toy guns operate on the same principle.) Maynard soon sold the rights to the U.S. government, and from the 1840s onward the army’s muskets and rifles were percussion-based.63
Early caps tended to be unstable because the copper sheathing was too thin or too cheap to contain the blast, and miniature shrapnel flew outward. But within a few years that problem had been surmounted, and designers turned their attentions to exploiting the new technology.64 As the quality of fulminates improved, caps needed less to fill them, and in 1831 the British Board of Ordnance found to its delight that not only had the traditional wastage of expensive priming-powder ended (the wind blew a lot of it away, and men poured more than was needed into the pan to ensure that it lit) but also that the mammoth annual bill for gunpowder could be slashed by a fifth. This was because the fulminate allowed a more efficient detonation of the powder, and so less of it was required to produce the same projectile force.65 Because of the reduction in the amount of unburned residue inside the chamber and barrel, infantrymen were not obliged to swab their guns as often, and the weapons benefited from not being subjected to as much wear and tear.
Armies also found that their supply headaches were eased somewhat by the caps. Historically, cumbersome wagon trains had prudently moved at a slow pace to prevent friction from causing accidental powder explosions, but caps were safe to transport and were more compact than barrels of priming-powder. Mr. Lovell of the Royal Arms Factory in England once conclusively demonstrated their safety by the simple expedient of thrusting a red-hot hammer into a tin box of five hundred caps. The only ones that exploded were those directly touched by the tool. His colleagues fired rounds into other boxes, with the same effect. The only way to blow up the entire box was to pour in gunpowder and ignite it.66
The cap led not to a revolution but to a reformation of military thinking. Since caps were waterproof, armies now had the option of campaigning in the winter and fall (even if gunpowder remained vulnerable to dampness), whereas the summer had been the age-old season for fighting. In order to man their armies for the longer duration, generals recruited more