Stone cannon shot were employed until 1520, and, when it was considered necessary to use very heavy projectiles, correspondingly enormous guns had to be built. Mons Meg, a well-known gun in Edinburgh Castle, of this large type, is a wrought-iron gun of the 15th century. It is built of iron bars and external rings, with a calibre of 20 inches, and it fired a shot weighing 350 lbs. Bronze guns, of a great size, were cast in 1468 at Constantinople, and one of them is now in the Rotunda at Woolwich. It was actually used in warfare against the English at the Dardanelles, in 1807. To show the destructive power of such a large piece of ordnance, even though a crude and ancient construction, it may be mentioned that the stone shot, weighing 700 lbs., which was fired from it against the English fleet, cut the mainmast of the British flagship in two, and another killed and wounded sixty men. These old 15th century guns in the battle altogether accounted for six of our men-of-war damaged and 126 men killed and wounded. The gun at Woolwich is in two pieces screwed together. The front part has a calibre of 25 inches for the reception of the shot, and a rear portion, forming a powder chamber, 10 inches in diameter. The whole gun weighs nearly 18¾ tons, and was presented to Queen Victoria by the Sultan of Turkey. Late in the 15th century, guns began to be more regularly employed on the battlefield. In the 16th century, the extremely large guns were discarded, and small, wrought-iron guns were made, this change being due to the use of cast-iron shot, which was as destructive as the more bulky stone shot formerly used. In 1521 the first bronze gun was cast in England, cast-iron cannon being made also in 1540, by foreign workmen, introduced into this country by Henry VIII. to teach the English the art. The first foundry was at Uckfield, in Sussex, and Sussex iron was used, smelted with charcoal. The small gun of this period was made very long, and a specimen is to be found in Dover Castle. It is known as Queen Elizabeth’s Pocket Pistol, and is 24½ feet long, with a bore of 4¾ inches. It was cast in 1544, and was presented to Henry VIII. by Charles V. Generally speaking, the English were much behind other nations in the use of artillery until the end of the 18th century. The quality of the gunpowder used in the early days of the cannon was very poor. The ingredients were often mixed on the spot at the time of loading, and the powder burnt slowly, with but little strength, and naturally varied from round to round. When the more fiercely-burning granulated powder was introduced into England, in the middle of the 15th century, it was often too strong for the larger pieces of that date, and could only be used for small firearms for more than a century afterwards. In the 17th century, bronze and cast-iron guns were strengthened, and were more adapted to the use of grained powder, and, at the same time, more energy and greater range were obtained.