As in these engines the impulse communicated to the projectile is entirely derived from the force with which the lever returns to the position from which it had been removed by the winding up, it is evident that they could never impress on the projectile a greater force than had been expended in winding them up; and as they were wound up by the power of the human arm, the sole ad vantage derived from their use was, that the minute successive exertions of human strength, slowly evolved during this operation, were, by their means, accumu lated, and simultaneously called forth in one great in dividual effort. Hence if the magnitude or velocity of the projectile were increased, the interval between each discharge, or the number of men, must be increased in exactly the same proportion. To expect that the im pulse communicated to the projectile should equal the whole amount of the power expended in working the engine, would indicate a very limited acquaintance with mechanics. In every machine a considerable portion of the power is lost in overcoming the friction, &c. of the machinery. The friction of the capstan, the rigidity of the rope, the imperfect elasticity of the spring, must have consumed much of the power applied to the an cient artillery. There was another circumstance more destructive of power in the balista than even these causes; the projectile was applied to the smaller ex tremity of the lever. and projected by partaking of its motion ; hence this extremity had a velocity equal to that of the projectile, and the motion of the other parts of the lever were in proportion to their proximity to this point. This motion was suddenly stopt by the lever striking against the cross beam, which limited the range of its movements. Hence at each discharge an impulse at least equal to that of the projectile was communicated to the lever, and entirely destroyed by the cross beam against which it struck. This disadvantage belonged to all the kinds of ancient artillery,•. though to some more than others. From this disadvantage the onager was the most exempt ; as in consequence of the motion being communicated through the intervention of a sling, the linal velocity of the projectile was considerably greater than that of the lever.
The artillery of the ancients, with all its imperfec tions, continued to be employed among the moderns till about the year 1336, when cannon were first invented. These powerful engines, on which modern warfare so completely hinges, were in their first form extremely unwieldy and inconvenient. They were of immense length and calibre, and formed of several bars of iron soldered together, and secured by strong hoops. They sometimes exceeded 20 feet in length, and 6 feet in dia meter. The difficulty of spunging and loading them was so great, that the same piece could seldom be fired above three or four times in the same clay.
The enormous weight of these pieces made it im possible to convey them from one place to another with any celerity, so that their use was confined to sieges. From the expense of making them, the number attached to an army was inconsiderable ; and though their charge of powder was comparatively small, they could not be often fired without bursting, or being otherwise render ed useless. With these disadvantages, their force did not much exceed the ancient artillery. It is not sur prising, therefore, that many of the best judges, at the time of the first invention of cannon, were inclined to prefer the cheaper and more portable artillery of the ancients, and that the latter continued in use for a con siderable period after the introduction of the former. In the course of a century, very important improvements were made in the form of cannon. It was found from experience, that their length might be reduced to one half, and yet their range rather increased. They were
reduced in calibre, and cast in one solid piece, by which, though the weight of the ball was diminished, yet as a greater charge of powder might be employed, both the force 'and the range were rendered greater, and a vast advantage was gained in the celerity of their move ments, and the frequency with which they might be discharged. Guicciardini informs us, that about the year 1494, the French in their invasion of Italy, carried along with them a number of brass cannon of a diminish ed size, drawn by horses, which could accompany the army in all their movements; and that they were point ed with incredible quickness, and fired at such short in tervals of time, and with such force, as to produce in a few hours as great an effect as the more cumbrous ar tillery produced in several days.
The earliest instance of the use of artillery in the field of battle is by the English at the battle of Cressy in 1346. " In the year 1347," says a French author, " these terrible arms were not employed in France against men : the French had, in 1338, used them to advantage in attacking certain castles ; but they would blush to employ them against their own likeness. The English, undoubtedly, less humane, conquered us, and employed them at the celebrated battle of Cresby, which toOk place between Philip de Valois and Edward the Third, king of England, who was so wicked and per fidious, and who gave so much trouble to the troops of the former ; and it was chiefly to the terror and confu sion occasioned by the cannon, AV IliCh the English used for the first time, and which they had posted on a hill near the village of Cressy, that the French owed their defeat." From this first use of field artillery a new az.ra commences in the art of war. The narrow front and deep columns of the ancients can no longer be used in the field of battle : armies are generally more extended into line, battles arc less general, and being commenced at greater distances, are less bloody. Warfare has be come more a matter of calculation, and skilful manoeu vres are now more decisive of a campaign, than the relative physical force of the combatants.
Mortars, a kind of short cannon, with a wide bore, and a narrow chamber for the charge of powder, were invented about 200 years later than cannon. At their first invention they were employed in throwing large stones and red-hot balls. They were subsequently ap plied to the throwing of bomb-shells, or hollow balls, filled with powder, to which a match is adapted of such a length as may burst the shell shortly after it has lighted on the object. The precise period at which this application was made of the mortar is not exactly known. It is generally attributed to a native of Venlo, in 1588 ; but there is reason to believe that its origin was at least fifty years earlier. The shell forms a most destructive weapon in the attack and defence of forti fied places. Those parts of the works which are com pletely protected from the direct, or even enfilading fire of the cannon, are yet exposed to the action of the bomb. The chief defect of the mortar is, that its eleva tion can be little varied, and that changes in its range must be chiefly produced by variations in the charge. This defect was remedied by the invention of the how itzer, a long time after the mortar. It has a chamber similar to that of the mortar, and, like it, throws a shell loaded with powder; but its length, the position of its trunnions, and the carriage on which it is mounted, re semble those of the cannon. As it can be fired at any elevation, it is one of the most useful pieces of artillery. elevations it serves the purposes of a mortar, and, at low elevations, its ball first acts as a cannon-ball, and then as a bomb-shell. It is also easily moved from place to place by an army.