146 POPULAR SCIENCE MONTHLY. 



With tlie construction and use of the materials employed in 

 modern warfare none but the professional military engineer can 

 be reasonably expected to attain much familiarity. But all have 

 an interest in national preparation for contingencies, and even to 

 the nonprofessional it may be an engaging study to trace in out- 

 line the evolution of the cannon as now made at great armories 

 like that at Watervliet, near Troy, New York. 



It would be only repeating an oft-told tale to show that our 

 remote human ancestors were all savages, and that the normal 

 condition of society among them was that of warfare. What 

 were the earliest weapons employed we can only conjecture. If 

 we disregard the long and for the most part unknown period 

 that preceded the beginning of definite human records, we find 

 that when these records began man was already acquainted with 

 the ruder processes of metallurgy. But there are no indications 

 that during the age of universal savagery metal was used to any 

 great extent for projectile purposes. Arrows and javelins were 

 early and abundantly employed, and the use of the sling was 

 undoubtedly common among the Israelites long before the 

 dramatic duel between David and Goliath. The Romans in 

 conducting their sieges employed the catapult and ballista for 

 the projection of large arrows and stones ; but from the vague 

 description of these instruments we can glean little more than 

 that they were probably immense crossbows. They were un- 

 wieldy, but powerful enough to project stones, each as heavy as 

 an ordinary man, over a distance of a hundred yards. During 

 the first dozen centuries of the Christian era there was but little 

 improvement over Roman methods of warfare. 



That the elastic force of hot gas suddenly evolved should be 

 substituted for that of a stout cord under great tension could not 

 have been possible without the previous discovery of the means 

 by which such gas could be appropriately generated. There is 

 no probability that we will ever learn definitely the true history 

 of the invention of gunpowder. Quite probably it was inde- 

 pendently invented by different persons at different times. There 

 can be little doubt that the knowledge of its composition existed 

 at a very early date among some of the inhabitants of India, 

 where the rich soil under a tropical sun has during many centu- 

 ries been leached for the puri)Ose of procuring niter. Assuming 

 the presence of this salt in abundance, it would hardly be possible 

 for one who handles it to remain long ignorant of its capacity to 

 explode when sufficiently heated in contact with charcoal, sul- 

 phur, or any other kind of fuel. It is not surprising that some of 

 the earlier alchemists should be credited with the preparation of 

 gunpowder. It has been common to attribute its invention to 

 Roger Bacon, whose life lasted through the greater part of the 



