thirteenth century. But his language is characteristically vague; for, in regard to the mixing of saltpeter with sulphur and another Roger Bacon. Born near Ilchester, about 1214; died probably at Oxford in 1292. undefined substance, he merely says, "You will thus make thunder and lightning if you know the method of mixing them." Another claimant to the invention of gunpowder was the German monk, Berthold Schwartz, who is said to have ground together in a mortar a mixture of niter, charcoal, and sulphur. Accidentally allowing fire to come into contact with the mixture, an explosion ensued. The pestle was projected from the mortar and from the hand of the surprised alchemist. This suggested the use of the uncanny substance for military purposes, and the mortar was subsequently made on a larger scale for the special purpose of propelling projectiles.

The determination of the proper percentages of niter, carbon, and sulphur in gunpowder implies a knowledge of the quantitative laws of chemistry. It is not to be supposed, therefore, that the earlier users of this explosive were able to make powder equal in quality to that of modern times, or that they knew how to adjust its granulation to the special purposes intended under varying circumstances. The Saracens seem to have introduced it into Spain for pyrotechnic purposes about the same time that Schwartz made his suggestion regarding its most important practical application. Its first definitely known use was for cannon. These were called "bombards," on account of the noise occasioned by firing.

The primitive cannon was a rude tube made up of iron bars hooped together, edge to edge, like' the staves of a cask. It was by no means readily portable, and was not provided with any wheeled carriage. As an offensive weapon its natural place was