trunnion axis which, as the force of powders increased, produced an increasingly great downward pressure on the trail. Carriages, though made of massive scantlings, frequently broke; nor was it till the latter half of the eighteenth century that the cause was removed, the trunnions being raised nearer the axes of the guns and the carriages being thereby relieved of the excessive cross-strains which they had borne for nearly three hundred years. Muller, in his Artillery, refers to the “absurd method” of placing the trunnions so low and, in the year 1768, points out the advantages to be gained by raising them. “Writers do not appear to have had any idea,” says Favé, “of the effect which the position of the trunnions had on the stressing of the carriage.” Scharnhorst the Prussian gives as an important advantage to be gained by raising the trunnions, the larger wheels which could be employed without adding to the height of the gun above the ground. Progress was also checked by the great length given to the smaller varieties of cannon. With the fine powder of the Middle Ages a great length of barrel was necessary to ensure complete combustion, and such primitive observations as were made all seemed to prove that, the longer the barrel the greater the range. But with the introduction of corned powder a reduction in length should have been possible. No such change was made. Tradition had consecrated long guns, and official standardization of types afterwards helped to oppose any innovation in this respect until the eighteenth century, with few exceptions. To Charles V of Spain belongs the credit for the first systematic classification of guns. In his hands artillery had, for the first time, become an efficient instrument of battle in land campaigns, and all Europe saw that, in his batteries of bronze trunnion-guns, on wheeled carriages, firing cast-iron balls against foe or crumbling masonry, a new power had arisen.[66] The emperor, experiencing the inconvenience of a multiplicity of types and calibres, sought to simplify his material. Accordingly, in the year 1544 or shortly before, he approved seven models to which all pieces in use throughout the vast possessions of the Spanish monarchy were thenceforth to conform. These seven types comprised a cannon (a 40-pounder), a cannon-moyen (24-pounder), two 12-pounder culverins, two 6-pounder culverins, and a 3-pounder falcon. The French soon improved on Charles’ example. The oldest patterns of their cannon, according to a table given by St. Remy in his _Mémoires_, were of a uniform length of ten feet. In A.D. 1550 Henri II issued an edict restricting the number of different calibres to six, named as follows:-- Canon, a 33-pounder, 10½ feet long, weighing 5200 livres, drawn by 21 horses. Grande coulevrine, a 15-pounder, 11 feet long, weighing 4000 livres, drawn by 17 horses. Coulevrine bâtarde, a 7-pounder, 9 feet long, weighing 2500 livres, drawn by 11 horses.