mander. The rest of the fleet also suffered considerably; but the defenders escaped with very little loss. In this engagement 8300 rounds were fired by the garrison, more than half of which consisted of red-hot balls. During this memorable siege, which lasted upwards of three years, the entire expenditure of the garrison exceeded 200,000 rounds,-8000 barrels of powder being used. The expenditure of the enemy, enormous as this quantity is, must have been much greater; for they frequently fired, from their land-batteries, 4000 rounds in the short space of twenty-four hours. Terrific indeed must have been the spectacle as the immense fortress poured forth its tremendous volleys, and the squadron and land-batteries replied with a powerful cannonade. But all this waste of human life and of property was useless on the part of the assailants; for the place was successfully held, and Gibraltar still remains one of the principal strongholds of British power in Europe.

During the progress of the siege, the fortifications were considerably strengthened, and numerous galleries were excavated in the solid rock, having port-holes at which heavy guns were mounted, which, keeping up an incessant fire, proved very efficacious in destroying the enemy's encampments on the land side. Communicating with the upper tier of these galleries are two grand excavations, known as Lord Cornwallis's and St. George's Halls. The latter, which is capable of holding several hundred men, has numerous pieces of ordnance pointed in various directions, ready to deal destruction on an approaching enemy.

In modern times one of the most striking examples of the power of gunpowder was shown in promoting the arts of peace. This was the experiment so boldly ventured upon by Mr. Cubitt, the civil engineer, who was employed to construct the South-Eastern Railway, and who, to avoid a tunnel of inconvenient length, determined to reduce the South Down Cliff, a portion of the chalk rock which girds the Kentish coast between Folkestone and Dover. The range of land between these two towns consists of a series of lofty hills, upraised by the chalk rock which extends from the middle of England to the centre of Poland, divided of course by the sea. It was desirable to avoid a long gallery, through which the trains would have had to pass, unless a durable sea-wall could be formed by which the carriages might proceed in open daylight. With characteristic force of intellect, Mr. Cubitt resolved to level this mighty barrier; and as the reduction of it, if accomplished by manual labour, would not only cost an immense expense, but would also occupy a great amount of time, the engineer determined to blow it up with gunpowder. Accordingly a gallery of small dimensions was opened in the rock from the western end; and at certain intervals chambers, or open spaces, were formed, in which large quantities of gunpowder were deposited. These chambers were then closed, only leaving

small openings for the communication of fuzes, or ropes having within them a copper-wire which communicated with a little house on the surface, at a considerable distance from the spot where the catastrophe was to take place. These wires were attached, at the other extremity, to a galvanic battery, which, by the passage of electricity through them, would fire the gunpowder. Mr. Cubitt was assisted by Lieut. Jackson, of the Royal Engineers. On the day appointed for the operation a large assemblage was gathered on the Downs to witness the result of the experiment. There was nothing to be seen but the undulating surface of the country, and the multitude of gay spectators of this novel sight, with the sea stretching in repose beyond, a little hut in which the operators were engaged, and a small rope, which, at a short distance, seemed to be lost in the ground. The battery was charged, and, after a few seconds, a low rumbling noise was heard, apparently under foot-an almost imperceptible upraising occurred, and, within a few seconds afterwards, the whole of the immense mass of rock, weighing upwards of 500,000 tons, was cast forward, and lay ground and shattered on the edge of the Channel waters. It was calculated that upwards of eight months of labour, and £10,000 of expense, were saved by this bold experiment. It was a sight not to be seen once in a century; it was the carrying of a stubborn and ancient barrier by peaceable science-a turning of the elements of war into the channels of civilization.

It is almost needless to dwell on the several other offices of peace which gunpowder fulfils, but we must not omit to mention the great aid it renders in bringing to the surface of the earth those metals which constitute one of the great sources of this country's wealth. Few sights indeed are more striking than that of blasting rocks in a mine. When it is requisite to remove a large quantity of earth or stone, a perforation is formed in the side, at the end of which a chamber or

open place is made, and into this cavity the gunpowder is introduced; a fuze, so made as to allow the work. men to get to a safe distance before it ignites the powder, is then lighted, and in a few minutes the rock is torn from its bed, and the miners are enabled to proceed in the extraction of the mineral wealth which this explosion may bring to light.

Who it was that first invented gunpowder is unknown. It was for a long time believed that its properties were first discovered by Berthold Schwartz, a Prussian monk, but it is now generally agreed that it was used by the Chinese, many centuries. before the Christian era, but only as an agent of peaceful arts, such as the levelling of roads, the reduction of hills, and the formation of canals, although some of their ancient pieces of ordnance seem adapted only for the use of gunpowder. Of its first application by them for the purpose of warfare we have no certain account; indeed, the earliest instance of its employment for the destruction of human life is found in the account of the battle of Crecy, fought with the French by our Edward III. in 1346.

Roger Bacon, the celebrated English natural philosopher, gives some obscure account of its composition in his treatise on Natural Magic, but, as just stated, to Berthold Schwartz the general knowledge of its real nature is traced. His discoveries were made known in 1336, ten years before cannon appeared in the field at Crecy.

Gunpowder is formed by a chemical mixture of nitre, charcoal, and sulphur, in different proportions. One would suppose, that as the objects to be attained are explosion, power, and rapidity of firing, or combustion, that the proportion of the several ingredients used would be the same for all purposes; but such is not the case. It is necessary, that whatever quantity of each ingredient be required, they must all be of the utmost purity. The charcoal is procured from burning alder, willow, or dogwood, and it is prepared, not in the usual way, but by consuming the woody fibre in iron retorts; the sulphur is of the volcanic kind, and is chiefly procured from Sicily, while the nitre is first fused to divest it of water, and afterwards wetted to enable it to mix with the other ingredients.

When these substances are in a fit state for mixing together, they are formed separately into pound powders, and then mixed in their proper proportions. They are afterwards sent to the powder-mill, which consists of two stones reared uprightly, and moving on a bed placed flat. On this bed the powder is deposited, and wetted sufficiently to enable the stones to act upon it without firing; but not so as to bring it into a state of paste. The stone runners are made to revolve over this mass until it is in a fit state to be sent to the cooning house, where it is cooned or grained. There it is pressed into a firm mass, and afterwards broken into small lumps and made to pass through sieves with small apertures, in which there is put a piece of wood called lignum

vitæ.