Andrew Hilliard Atteridge

“ When the explosion occurs in a confined space, the weakest portion of the confining bodies gives way before it. In quarrying, the rocks are rent, as the gas from the blasting-powder forces them apart. In blowing down walls and gates, the mass of earth heaped on one side to form the "tamping" offers a greater resistance than the wood or stone on the other, and the wall or gate gives way. In firing a cannon, the loose shot offers less resistance than the solid coils of the gun, and it is driven out to a distance proportioned to the force of the charge. ”

“ Much alarm has been caused not only in London but throughout the kingdom by this explosion in the heart of the metropolis, and it will have a useful effect in calling attention to the dangerous character of a material so largely employed as gunpowder, and the consequent necessity of carefully regulating its manufacture, storage, and transport, and seeing that these regulations are strictly enforced; for, no matter how perfect our precautions may be in theory, they are worse than useless if we cannot secure their practical efficiency. ”

“ What a contrast to the early days of gunpowder-making, when in France, in 1375, a pound of gunpowder cost a sum equal to ten pounds of our money!
In every department the greatest care is taken to prevent the danger of explosions. The houses are built from 200 to 400 yards apart. Wood, copper, and gun-metal, are the only materials used in the structure of the machines, except where, and that rarely, a bolt of iron is introduced for the sake of strength, and then the metal is encased in leather. ”

“ Every powder-barge is considered a magazine, and the same rules apply to it as to the Government magazines. No fire or light is allowed on board; nothing but powder is to be placed in the hold; and no one is allowed to enter it without wearing the ordinary magazine shoes. In this way it may be said that every chance of an explosion is carefully guarded against. It would be well if the same method of transport were used on canals where (as on the Regent's Canal) gunpowder is being continually carried to and fro. ”

“ With the immense guns constructed in recent years, it is important to reduce the strain on the metal as far as possible, as this is the only way in which the gun can be safely fired. But it must be remembered that, by seeking to accomplish this by indefinitely increasing the density of the powder, we would at the same time decrease the velocity of the shot, or, in other words, its useful effect. Artillerists have, therefore, had recourse to the expedient of using a powder, each grain of which is a lump of press-cake. The effect of this is to make it burn slower than grain-powder ”

“ In Europe, where there is an extensive telegraph system in operation in every country, there is no need of the field telegraph-lines extending from the front of the army to the base of operations. Far less than this is required. All that is necessary is to connect the headquarters of the army with the nearest point on a permanent telegraph-line, and in most European countries an army in the field would seldom, if ever, be more than ten miles from such a line. Ten miles of the field telegraph can easily be erected in half a day ”

“ If there is any defect impairing the strength of the cannon, or if the shot wedges in the bore, the gun bursts; for nothing we know of can resist the force of the gas. Recent experiments prove that this force, exerted in closed vessels unrelieved by expansion, is equal to a pressure of about forty tons on the square inch.
Of the three materials of which gunpowder consists—sulphur, charcoal, and saltpetre—only the last two are, strictly speaking, essential to it. The gas is actually generated from the charcoal and saltpetre, therefore a mixture of these only will explode. ”

“ A pair of iron runners, driven by steam and working day and night, will incorporate in a year nearly 100,000 pounds of cannon-powder, or about half that quantity of rifle-powder.
This part of the process is more dangerous than any other, and explosions in the incorporating-mills are very frequent. The houses are built of light planking, nailed on a strong framework, so as to diminish the force of the explosion by yielding easily before it. ”

“ Since then great improvements have been introduced into the manufacturing process; the factory has been widely extended, gun-metal and copper have been largely substituted for wood in the structure of the machines, refining-houses have been erected for purifying the saltpetre and sulphur, and retorts for preparing the charcoal. Machinery has been designed and erected for the preparation of the large cannon-powder introduced of late years, and in the mills iron runners, driven by steam, have taken the place of the stone runners, drawn by old horses. ”

“ The charcoal is all made on the spot, chiefly from wood imported from Holland and Germany. The alders and willows in the plantations of the factory furnish but an insignificant supply, probably not enough to make a dozen barrels in the year. They are grown for the most part to form screens around and between the houses, so as to diminish the danger resulting from a possible explosion. The wood employed is of three kinds—alder and willow, which are used for common powder, and black dogwood for fine rifle-powder for the Snider and Martini-Henry. ”

“ As the mountain line would have to be laid along narrow, rocky paths, and through lofty passes, all carriages and wagons are dispensed with, and their place is taken by a train of mules. In a mountain-telegraph company several of the mules are each laden with two drums of the insulated cable, the instruments and batteries are carried on pack-saddles on the backs of others, and others again transport the baggage, provisions, and forage of the company, and also a light tent to form a station whenever messages are to be sent along the line. ”

“ The men are forbidden to remain in them while the mill is in motion, and a very simple arrangement has been devised for preventing an explosion from extending from one mill to another. A shaft runs horizontally through the upper part of the walls of each row of mill-houses. A shutter, balanced by a weight on the other side of the shaft, projects from it over each mill, and this shutter supports one side of a water-tank, the other resting on a pivot. ”

“ The factory gives employment to about two hundred men, and can produce twenty-four thousand barrels of gunpowder in the year, and the powder is believed to be at once the best and cheapest made by any existing factory.
Before describing the process of its manufacture at Waltham, it may be as well to note a few facts on its composition and action. Gunpowder may be regarded as a solid, which, by ignition, can be very rapidly converted into a large volume of gas at a high temperature. ”

“ The transport, however, might easily be rendered much safer, by forbidding gunpowder-carts to pass along the streets except during a few hours in the morning, allowing only covered vans to be used, and fixing certain intervals within which no van should approach another. Finally, powder should never be packed in the light kegs used by some manufacturers, which are continually liable to leak, for loose powder is always exposed to ignition by any one of a hundred accidents. ”

“ On exhausting the air, closing the first cock and opening the second, the mercury is forced into the globe, and completely fills it. It is then weighed in a delicate balance, and, its weight when filled with mercury only being known, it is easy to calculate the density of the gunpowder.
Its force is ascertained by observing the initial velocities which it will give to a shot fired from a cannon. ”

“ Thus cannon-powder is left under the mills for three hours; while for rifle-powder, which requires a closer incorporation on account of its more rapid action, the time is five hours. The power of a gunpowder-factory is measured by the number of pairs of runners it possesses, for, as the law allows no more than 50 pounds to be placed in any mill at one time, the amount which can be incorporated in a year is easily calculated. ”

“ The runners are either of black Derbyshire limestone or of iron, and weigh from three and a half to four tons. Iron runners are now generally used, and their size varies from three and a half to seven feet in diameter. The mill-bed, a large circular vat with a flat bottom and sloping sides, is of stone or metal, according to the material of the runners. On this bed 50 pounds of the green charge is spread out and moistened with water, and the mill is then set going. The length of time required for the incorporation of the powder varies according to the use to which it is to be applied. ”

“ During the invasion of France the Prussians frequently avoided the roads in order to protect the line from the franc-tireurs, and made considerable détours, concealing it in woods, ravines, and water-courses. Where the uninsulated wire is used, poles are erected about fifty paces apart, the hole to receive each pole being made by driving a sharp pointed iron bar into the ground with a heavy mallet. As soon as a pole is fixed the wire ”

“ Again, even without occupying a station, it is possible to read the messages which are passing along a telegraph-line, and thus perhaps discover important secrets. All that is required for this purpose is a small portable receiving instrument, and a few yards of copper wire to connect it with the line. A single individual, thus equipped, can "tap" a telegraph-line, in the daytime, by receiving the message in the ordinary way ”

“ While the field telegraph affords a commander a rapid and certain medium of communication with his base of operations and the various corps of his army, it must be remembered that it is one which is continually liable to interruption by an enterprising enemy. ”

“ Under the seat is a recess in which a spare instrument t is kept, while the batteries are arranged in a box b under the shelf. When a message is to be sent from this movable station the wagon is stopped, and the line-wire is attached to the insulated conductor i. This is connected with the instrument and battery, and in order to complete the circuit the battery is placed in electrical communication with the second insulated conductor, to which another wire is attached which joins it to the earth-conductor or earth-stake (piquet d terre) (Fig, 5) . ”

“ The substances thus formed, swept out into the air, become flame and smoke, or remain in the bore of the gun as fouling, and it is these solid substances that blacken the faces of men engaged in close conflict.
Thus we see that of the materials of gunpowder saltpetre is the most important. Both saltpetre and sulphur arrive in England in a rough state, mixed with various impurities. It is generally the practice in private factories to purchase these materials after they have been refined elsewhere; but at Waltham the refining process is carried on within the works. ”

“ On leaving the mill, the gunpowder is in the form of a soft cake, which easily breaks up into meal and dust. The old plan for making gunpowder, still followed in some places, was to moisten this mill-cake and force it through fine sieves, so as to break it into grains; but the moisture partly dissolved the saltpetre, and thus, to some extent, destroyed the previous incorporation, and the result was an inferior gunpowder, which, on account of the softness of the grains, often broke up into dust in transport. ”

“ Earth-conductor.
is run through the hook on the top of the insulator, and stretched tight by a man holding it over his shoulder, who keeps it in this position until the next pole is ready to receive it. Wherever there are trees or walls near the line, the work is still further lightened by dispensing with the poles, and merely attaching the wire to the insulators specially constructed for this purpose. ”

“ Wherever a general has to contend with ah army well provided with good cavalry, he will find it extremely difficult to protect his telegraph-lines from being destroyed by daring raids of his opponents. There are several easy ways of making a telegraph-line temporarily useless. The simplest and most obvious method is to pull down the poles and cut the wires into pieces; but when this is done the damage is easily detected ”

“ If the enemy's cavalry get possession of a station, they can easily send messages containing false information or delusive orders to well-known officers of the opposing force, while the place from which they are sent, and the assumed name in which they are dispatched, will give the messages an appearance of authenticity which, if it does not completely deceive the recipient, will at least be the cause of considerable doubt and perplexity to him, and perhaps make him hesitate to accept the accurate information or authentic orders received from other sources. ”

“ In the case of a ground-line it is simply paid out from the drums on the hand or wheelbarrow, being buried in a shallow trench or elevated on poles, when it is necessary to cross a road, where the insulation of the cable might otherwise be injured by the wheels of passing vehicles. ”

“ It is not too much to say that, without this wondrous power, it would be almost impossible to direct the movements of the thousands on thousands of men, and guns, and horses, which form the vast armies of Continental Europe. ”

“ When it is required for use in the Gunpowder Factory, it is purified by a process founded on the principle that hot water will receive in solution more of the saltpetre than of the impurities mingled with it. ”

“ At the same time a few poles can be pulled down in another place, and the wires cut, and the probability is that the engineers who repair the line will not discover the hidden interruption of the circuit until after they have restored the gap, and found that the wire is still cut somewhere else, and even then the place where the non-conducting substance is introduced will not be discovered until some time has been employed in carefully testing the line with the galvanometer. ”