| Saltpetre. | Charcoal. | Sulphur. | |
| 69.0 | 16.5 | 14.5 | for big guns; |
| 72.4 | 14.5 | 13.1 | for small guns; |
| 75.7 | 13.0 | 11.3 | for small arms.” |
The information given to us about granulation by the early English gunners is neither clear nor full.
When Whitehorne tells us that the method of corning “all sorts of powder” was the same, namely, by means of a sieve and a few heavy metal balls,[470] what meaning did he intend to convey by the phrase “all sorts of powder”? There can be little doubt that he meant “powders of whatever composition, and whatever the size of the grain to be produced;” first, because it would be preposterous to assume that all the sieves of his time had meshes of equal size; and secondly, because there is abundant evidence to show that, long after Whitehorne’s time, the powders for different guns in England (and elsewhere) varied both in composition and grain. In 1620 Thybovril and Hanzelet tell us that powder to be granulated is to be passed through a sieve with holes “de la grosseur que vous desirez votre poudre”;[471] and eight years afterwards Norton uses the very same ambiguous phrase, “a syve ... made full of holes of the bignesse you desire your cornes.”[472] Did they mean that the size of the grain in their time was purely arbitrary and might be of any magnitude whatever? A passage in Boillot’s (earlier) work explains their meaning much better than they have done it themselves. He first tells us that the sieve is to have holes “de telle grosseur que vous voudrez,” and he then goes on to explain the proper size of grain for use in the different classes of ordnance, as given here on a previous page. In a word, three or four kinds of sieves (differing in the size of their meshes) were procurable—some for graining powder for big guns, others for graining powder for medium guns, &c. &c.—and having fixed upon the gun from which your powder (when grained) was to be fired (and consequently upon the size of the grain), you were to select those sieves which had meshes “of the bignesse you desired your cornes.”
From the phrase used above by Norton, it is certain that several powders, differing in grain, were in use when he wrote; from the evidence of Norton,[473] Nye,[474] and others, it is equally certain that several different receipts for making powder were in use during their time. The conclusion is that during the first half of the seventeenth century powders made in England for different guns varied both in composition and size of grain.
The lawlessness in composition and grain during the greater part of the Transition Period was the natural consequence of the absence of any instrument to measure the comparative strength of different powders, and enable gunners to establish some standard for the proportions of the ingredients and the size of the grain.
The earliest instrument proposed for testing the strength of powder was, I believe, Bourne’s “engine or little boxe,” which, he says, was “very necessarie to be used.”[475] Whether he invented it himself or not, it is impossible to say: he tells us, “some of (the inventions) I have gathered by one meane and some by another, but the most part of them hath been mine own.”[476] The engine was a wretched one. The powder to be tested was ignited in a small metal cylinder with a heavy lid (working on a hinge) which when raised could not shut of itself. The angle through which the lid was raised by the explosion indicated the strength of the powder.
A better instrument was that described by Furtenbach in 1627.[477] It differed from Bourne’s “little boxe” in that the lid was only laid upon the cylinder. When the powder exploded the lid was blown upwards along two vertical wires which passed through it; but it could not descend again of itself, being held in the place it reached by iron teeth (like those which supported the lid of Bourne’s box). Nye describes this instrument, and suggests that the comparative strength of powders should be further tested by measuring the penetration of pistol balls into clay, and the ranges of projectiles fired from a small mortar.[478] This is, I believe, the first proposal of the mortar éprouvette, 1647. The French certainly adopted them before 1686, often though it has been said that they then introduced them. On the 18th September of this year Louis XIV. published an ordonnance complaining of “the variety of eprouvettes” in use for testing powder, and directing that for the future no powder should be accepted unless 3 oz. of it could throw a ball of 60 lbs. 50 toises (320 ft.) from the Government pattern mortar.[479] In a previous ordonnance (April 16, 1686) the King had protested against the bad charcoal (de méchante qualité) constantly employed; against impure saltpetre (rempli de graisse et de sel), insisting upon the exclusive use of saltpetre “de trois cuites”; and against insufficient incorporation (dix ou douze heures ... au lieu de ... vingt quatre heures).[480] But he marred the reforms he made by taking the unaccountable step of introducing one powder, of the same composition and size of grain, for all arms.[481] For this blunder the French afterwards paid in blood, especially during the Peninsular war.[482]
About the beginning of the eighteenth century most countries had reduced their powders to two or three, which were of the same composition, and differed only in grain. In 1742 Benjamin Robins, by his “New Principles of Gunnery,” placed gunnery upon a strictly scientific basis, and by his epoch-making invention of the ballistic pendulums[483] enabled gunners for the first time to measure the muzzle-velocity of projectiles with considerable accuracy. It may have been owing to the lessons taught by this instrument that, between 1742 and 1781, we changed the proportions of the ingredients of our powder from 75—12½—12½ to 75—15—10. Profiting by the rapid progress of electricity during the first half of the nineteenth century, Sir Charles Wheatstone proposed in 1840 his electro-magnetic chronoscope,[484] which registered to the 1/730 part of a second, to replace Robins’ ponderous pendulum.