Major Mordecai arrived at valuable conclusions concerning the charges for cannon and small arms; the form of the cartridge for heavy guns; and particularly concerning the proof, the hygrometric test, the mode of manufacture, the size of grain, &c., of gunpowder, to the trial of which his experiments have been particularly directed. From these scientific investigations we turn to the practice of gunnery, which they are designed to promote and improve; and this we shall consider under the heads of range and penetration. We have already defined the objects of the art of gunnery to be, to direct the shot or shell to a certain point, which, with all its various details of execution, is included under the head of range; and 2, to regulate the force of impact so that the shot or shell will either possess great momentum as in breaching walls, or only sufficient penetrating power to enter and remain fixed in the object, as in exploding shells in a ship's side, which is embraced in penetration.-Range. In the text book of the military school at St. Cyr, it is directed that the fire of artillery should cease when the enemy is at 1,000 or 1,200 metres distance; and Col. Piobert, in his Traité d'artillerie, prescribes 1,600 or 1,700 metres as the limits of ricochet practice in the field. It has hitherto been usual for opposing bodies in an open engagement to take their stand at about 1,000 yards from each other, more or less according to the nature of the ground and other circumstances. At Waterloo the distance was 1,200 yards, and the armies were out of the reach of all but solid shot from field guns, as they were fitted and served at that time. But the recent changes in fire-arms, especially the introduction of rifles and shell guns, liave completely overthrown the old systems. Now troops can shoot each other with their rifles at 2,000 yards; and at the first trial of the Armstrong gun at Shoebury Ness, a shot and a shell were projected by it 5 English miles. But not only is the extent of range wonderfully increased, but so also is the accuracy of aim; or in other words, the deviation or difference of range is diminished. It is stated that at the same trial the Armstrong gun was compared with an ordinary 9-pounder field gun, and that the mean lateral deviation of the former was less than one foot, while that of the latter was over 9 feet. To use the words of the writer: "Armstrong's gun could hit a target 2 feet 6 inches in diameter at 1,000 yards, while the service gun could not be depended upon to hit a haystack at the same distance; at 1,500 yards the aim of the brass gun became wild, while the rifled cannon maintained its relative accuracy up to at least 3,000 yards, and even beyond that." It was the deliberate opinion of the late Gen. Jacob, an old artillery officer, a rifleman, and a practical mechanic, "that a 4-grooved rifle iron gun, of a bore of 4 inches in diameter, weighing not less than 2,400 lbs., could be made to throw a shot 10 miles or more with force and accuracy." If to this possible range of great guns we add the improved range of the Minié or Enfield rifle,

we shall perceive, without further argument, the important bearing of the subject upon naval as well as military warfare. As this article does not aim to be a systematic treatise on naval gunnery, we shall simply say, without assigning reasons for it, that the point-blank range, always preferable, is especially to be relied upon on board ships, and preeminently so where rapid firing is to decide the affair. But Dahlgren's practice at Washington (see "Shells and Shell Guns," by J. A. Dahlgren, commander U. S. N.) has shown that the chances of getting to close quarters are now not so favorable as they were before the invention of his own and other 8-inch and 10-inch shell guns and their missiles. Upon this point we may refer the reader also to table V. of Sir Howard Douglas's "Naval Gunnery," which contains the " ranges with seaservice iron ordnance, single-shotted, obtained on board H. M. S. Excellent." Naval guns are now fitted with graduated tangent scales, or scales of elevation, on which are marked either ranges in yards, or elevations in degrees and parts of a degree. The adaptation of them to the guns of our navy was commenced by Commander Dahlgren, under the orders of the naval bureau of ordnance, in 1848; and tables containing the angles of elevation answering to different distances are furnished in the "Ordnance Manual." These tangent scales are made of brass and fitted to the breech of the gun; and the degrees are counted above the line of dispart, or above the line of sight which is parallel to the axis of the piece.-Penetration. The inquiry into the injury effected by the new ordnance and missiles, at the distances mentioned by the authors we have referred to, brings us to the subject of penetration. It will be readily understood that the nature of the service to be performed must be taken into account by the gunner; otherwise he may throw away his powder and ball. If, for example, he is superintending the operations of a siege train with which he is to open a passage for troops through the walls of a fortified place, he will consider that the force of the blow depends upon the weight and velocity of the ball, and that the momentum on striking is in proportion to the initial momentum; he will, therefore, make use of solid shot and high charges. If, again, he is directing his fire against ships, within easy range, he will remember that it is not the shot that are projected with such velocity as to pass entirely through a ship that commit the most havoc, but those rather that have just sufficient momentum to penetrate, and tear off the greatest number of splinters. In this case shot of inferior weight, or moving with less velocity, will cause the greatest rents and ravages in timber, will make the largest and most numerous splinters, and will open holes of an irregular shape and very difficult to plug up. If, again, uncovered masses of men are the objects of fire, grape, canister, shells, and shrapnels will be resorted to, the two latter with Col. Bordmann's fuse properly set according to

the distance, so that they will explode over or among the enemy. If, again, the contest is between a casemated battery and ships at a short distance, the former having large embrasures, the ships ought to fire canisters of musket balls. "It is difficult to understand how a casemated battery having large embrasures can be served at all, after a ship has gained a position within a short distance, and opened her fire of small canister balls. For the ship to fire grape, or large canister balls, would be to abuse her opportunity, since these larger balls would be no better in any such conflict than the smaller ones, while they would be far less numerous. Musket balls, used as canister shot, would have all the force necessary, and there would be thrown of these, in half an hour, into the casemate, through 24 embrasures of 54 square feet of area each, by 50 32-pounders, no fewer than 33,696, being 1,404 through each embrasure. Were the battery to retort upon the ship with the same missiles, the advantage would still be greatly with the ship, because against the 1,404 balls received by each embrasure, there would be thrown but 126 into each port, and into the 50 ports there would be returned but 6,300 shots against the above number of 33,696 poured into the 24 embrasures." ("Casemate Embrasures," by Brig. Gen. Joseph G. Totten, chief engineer U. S. A.) The experiments upon penetration have been numerous and various in Europe and the United States. Sir Howard Douglas gives a table of penetrations into oak from the Aide mémoire navale; Capt. Dahlgren also presents a similar table of experiments upon seasoned white oak; and M. Piobert, in his Traité d'artillerie, has given tables professing to contain the results of experiments made in France on the depths of the penetration of shot into masonry, wood, earth, and water, from guns of different calibres, with various charges of powder, and at different distances from the object struck. See also the Mémoires of Lieut. Col. Duchemin and M. Poisson in the Journal de l'école polytechnique, Nos. 24, 26, 27. For an account of grooved guns, and of rotating balls, see RIFLE, and RIFLED ORDNANCE. GUNNY, a coarse cloth made in India of the fibres of two species of corchorus, and used for the sacks in which saltpetre, pepper, and other articles are packed for exportation. The bagging itself is also exported. The bulk of the Calcutta exports of gunny bags and cloth finds its way to the United States, and is mainly used at the South for cotton bagging. In the year ending June 30, 1858, the amount was as follows:

000 worth of cloth were reexported, chiefly from New York, and principally to Chili and Peru.

GUNPOWDER, an explosive compound of nitre, sulphur, and charcoal, differing from the fulminates by being less instantaneous in its action when ignited. It is consequently better adapted for throwing projectiles and shattering rocks in blasting; and to these uses it is appropriated to the exclusion of other explosive preparations. Its composition and character appear to have been known to the Hindoos at a very early period-in the opinion of some versed in their annals, as far back even as the time of Moses; and through the Arabs a knowledge of it is supposed to have been brought from the East to Europe. In the life of Apollonius Tyanæus, written by Philostratus, is a passage referring to some explosive material which was used as a means of defence by the Oxydraca, a people living between the Hyphasis and Ganges, and whom Alexander is supposed to have declined attacking in consequence: "For they come not out to fight those who attack them, but those holy men, beloved of the gods, overthrow their enemies with tempests and thunderbolts shot from their walls." The Egyptian Hercules and Bacchus, who overran India, were repulsed by these people "with storms of thunderbolts and lightning hurled from above." The invention of gunpowder has been popularly attributed to Schwartz, a German monk and alchemist of the 14th century, and also to Roger Bacon, who described it in his writings about 1270. The latter, however, referred to it as a substance already in common use for the amusement of children. The receipt which he gives for its manufacture is thus translated: "But, yet, take of saltpetre, with pounded charcoal and sulphur, and thus you will make thunder and lightning, if you know how to prepare them." Its early use is further treated in the article ARTILLERY. The invention and application of this material, capable of exerting such immense influence in the affairs of nations, cannot but be regarded with admiration, when the selection and combining of its ingredients would seem to have demanded much more chemical skill than belonged to the age in which it was produced. It is also remarkable that so powerful an agent should lie hidden in three substances, all easy to be procured, giving to those nations that possess the skill to combine them a vast superiority over the more ignorant. This result, however, is the more striking in modern times, in the improved methods of applying gunpowder in practice.-The earliest known receipts for making gunpowder combine, according to Dumas, the same ingredients in similar proportions to those now adopted as the best; these are 75 parts of saltpetre, 12.5 of sulphur, and 12.5 of charcoal. The Chinese receipt is not very different. But the proportions recommended by some of the English and French authorities of the 14th century indicate a want of uniformity in making the mixture and an ignorance of the best proportions; all, how

off fragments in contact with the charge with great violence and a loud report, but do little of the real service required. Such powder should be provided for military service to be used when required for exploding mines, instead of the ordinary artillery powder. To further increase the time consumed in exploding, this powder is also made of very coarse grain; and Greener strongly recommends that sporting powder should be made of the same coarseness, as its great propelling force would thereby be exerted with continually renewed effect upon the projectile while this is passing through the bore of the piece. To attempt to secure this advantage by increased proportion of sulphur would be to weaken the powder by involving reduced gaseous expansion, and to risk fouling the piece with injurious sulphurous products, generated directly by union of the sulphur with the potash, or indirectly by the sulphuret of potassium after the discharge absorbing moisture from the air, and thus giving rise to sulphuretted hydrogen and sulphate of potash. -The materials employed in the manufacture of gunpowder should be selected and prepared with special reference to their purity and best conditions for producing the effect desired. Charcoal, more than the other ingredients, is liable to vary in its character. This is owing as well to the different qualities of the woods from which it may be made, as to the different methods employed for preparing it. Woods which give a hard flinty coal are objectionable on account of the slowness of its combustion, the comparatively small amount of gas it produces, and the deliquescent salts, as carbonate of potash, which it contains. The porous charcoals which contain some hydrogen are much to be preferred; such are those made from the wood of the black dogwood (rhamnus frangula, a species of buckthorn), the alder, and the willow. In France the black alder is exclusively used; and of this the smaller sized branches are preferred. They are stripped of their bark, as this would introduce too much inorganic matter. In England black dogwood is used for sporting powder; willow and alder by the government. In the United States the willow is largely cultivated about powder works, and the plants are kept down to small size by frequent cropping of their rapidly grow ing shoots. These excellent woods, however, may be rendered as unfit for this manufacture as the hardest coals, if they have been charred at too high a temperature. The experiments of Violette, already referred to, establish the fact that charcoal ignites most readily when the temperature attained in its preparation does not exceed 500°. Such coal enters into combustion when afterward subjected to the temperature of 680° or less; the coal of lighter woods more readily than the harder kinds. When charred at degrees of heat ranging from 536° to 662° it ignites at 698°; and thus the temperature required for igniting increases according to that employed in coaling, till it is found that if the

charcoal has been made at the heat required to melt platinum, it may enter into combustion but slowly even when heated to a point estimated at 2,282°. This takes place with the most combustible kinds of charcoal. It thus appears that the most inflammable powder must be made with charcoal carefully prepared at a moderate heat; and that the thoroughly carbonized black coal, that has been subjected to higher temperatures, is better adapted for blasting and artillery powder than for rifle use. Whether the carbonization be effected in pits or retorts, it requires greater care to regulate the process than when charcoal is made for other uses. The retorts, of cast iron, when charged, are heated to redness. Being of cylindrical form, the powder from charcoal prepared in them is called in England cylinder gunpowder. The crude nitre employed in the manufacture requires to be purified in order to separate the deliquescent chlorides of sodium and of potassium and other impurities which are always present. It is dissolved in water, the solution is strained, and then concentrated by evaporation, when the chlorides first separate and are removed before the nitrate of potash crystallizes. The crystals when formed are taken out and redissolved in pure water and again refined. The sulphur is refined by fusing the rolls, when the lime and sulphuret of calcium present subside, and other impurities are skimmed off. If the flowers of sulphur are used, they should be washed with water in case of sulphuric acid being present. The melted sulphur after refining must be ground to impalpable powder and bolted. The nitre and the charcoal are also treated in the same way, the mills employed sometimes being the same as that for the next process. The ingredients are then carefully weighed and sifted into a trough or a cylinder especially contrived with revolving fans, in which they are mixed together. The compound is then taken to the powder mill to be thoroughly incorporated together. This mill is on the same plan as the Chilian mill, used for grinding gold ores. Two rollers of cast iron, weighing about 3 tons each, are made to revolve around a vertical shaft upon a cast iron bed, which is surrounded with wooden sides, set up of staves like the sides of a tub. It is in a small building by itself, on account of risk of explosion. The operations at powder works are for this reason distributed as much as possible in numbers of isolated buildings, and upon some stream which supplies water power at numerous points. The quantity of powder introduced into the mill to be ground at once is from 40 to 50 lbs. It is kept slightly moistened with water to prevent its forming dust, while it is subjected to the grinding of the heavy wheels rolling and twisting round for 3 to 5 hours. The greatest care must be taken that no gritty substances enter the mill. The grinding completed, the mixture is cautiously taken out of the mill. In drying, it cakes together in hard lumps of a grayish black hue, which are called mill cake. It may now be broken up between grooved

rollers, or introduced directly into the press, and subjected between copper plates to a hydraulic pressure of about 120 tons to the square foot. A screw press is objectionable from the danger of the powder dust floating about being ignited in the screw. The mixture comes out of the press in flat blackish sheets like slates about inch thick. By this operation the powder is rendered dense and firm, and when afterward reduced to granular form it is thereby more efficient, and also less disposed to absorb moisture and to be rubbed to dust by friction in transport. Mealy powder explodes with comparatively little force, and the mill cake when ignited may be said rather to burn furiously than to explode. The powder must be reduced to grains to produce the effect required; and this is done by the process called granulating. The press cakes are first broken up by wooden mallets, or between pairs of rollers, toothed or plain, revolving near together, and the fragments are then received in sieves made of vellum pierced with holes of an inch in diameter, and moved forward and back by machinery. Two disks of lignum vitæ, 2 inches or more in thickness, and 6 inches in diameter, are placed in each sieve to rub and grind the powder, and cause it to work through. The powder is then assorted by means of wire sieves of different grades. The dust separated by a sort of bolting is returned to the press. In some works the machinery is arranged to complete this process without exposing the work men to the danger of attending it. The edges of the grains must next be worn off, to lessen the tendency to the production of dust in the casks by friction. This process, called glazing, is effected upon parcels of 200 lbs. placed in a barrel, which is made to revolve for some hours at the rate of about 40 revolutions a minute. To give a real glazing or polish, as is done to some kinds of sporting powder, the cylinders are lined with woollen. Greener condemns the whole process as unnecessary, and "injurious to the quick and certain ignition." After the glazing the gunpowder is dried at a temperature of about 140°, produced by steam pipes or heated air. It is finally sifted, and is then ready to be packed in casks, kegs, or canisters. The use of nails is carefully avoided in securing casks and kegs. The hoops should be of wood, or if, as practised in England, of copper, the rivets should be forged and not cast, several accidental explosions having occurred from the fine sand attached to the copper cast in moulds. -The quality of gunpowder is judged of by its uniformity of texture, its firmness and cleanliness, by its not being easily crushed in the fingers, nor readily soiling them. A sample of it flashed upon white paper should blacken this but little, and not inflame it. The appearance of sparks indicates imperfect incorporation of the ingredients. Its degree of inflammability should be observed, that the powder be sufficiently and not too quick for the purpose required; though there is no danger of powder

made with nitre acquiring the highly explosive character of the fulminates. The quickest kind, laid in a train and crossed at right angles by another of fulminating mercury and fired at one end, may flash off till the fire reaches the fulminate and explodes this, when its further progress is arrested, the grains of gunpowder being scattered before they can be heated to the point of ignition. Gun cotton may be fired upon or even under gunpowder without this being ignited. In examining powder, in case the grains adhere together, the powder is known to have absorbed moisture, perhaps enough to materially injure it, so that even drying will not restore it. The effect of the moisture is upon the nitre, dissolving it and separating it from that intimate mixture with the other ingredients, upon which the value of powder depends. Even if apparently restored by drying, the powder is not so strong as before, and is more likely to become dusty by the friction incurred in transporting it. A partial analysis is frequently adopted to determine the quality of the powder. The moisture, commonly a mere trace, is ascertained by drying a weighed sample at a temperature of 212° and again weighing. The nitre is next dissolved out, either by boiling the powder in distilled water, or washing it (placed in a filter) with hot water. The solution, separated from the insoluble portion, may be evaporated to dryness, and thus the nitre is separated, and may be subjected to the usual tests to determine the presence of chlorides, which may have been introduced by original impurity of the nitre or by the powder having been damaged by sea water. The strength of powder is tested by the effect of weighed portions upon heavy projectiles discharged from pieces made for this use, and called eprouvettes; or in some eprouvettes the force is measured by the compression of strong springs, against which it is exerted.-A highly inflammable and powerful gunpowder may be made by mixing 2 parts of chlorate of potassa with one of white sugar and one of ferrocyanide of potassium, the ingredients being first separately pulverized. The powder, when granulated in the usual way, is in white grains. It has the advantage of not absorbing moisture from the air, so that it may be kept without incurring damage; it can also be readily made on a large or small scale; and the materials being of fixed composition, its strength is likely to be uniform. If care be taken that no charcoal or sulphur is introduced into the mixture, there is no greater danger attending its use than that of ordinary gunpowder. It is liable, however, to oxidize iron barrels rapidly, and is therefore fit only for bronze pieces or for hollow projectiles.-In 1856 Great Britain exported 10,500,018 lbs. of gunpowder, valued at about $1,600,000, chiefly to the W. coast of Africa, Australia, South America, British North America, and British East Indies. The exports from the United States in the year ending June 30, 1858, amounted to 2,778,414 lbs., valued at $365,173. The man