Sec. XXIX. Of the Succouring Rocket.

The succouring, or marine rocket, is a name given to a rocket, which is sufficiently large to convey a small cord or rope to some distance from a vessel, and by its means to save the lives of persons in danger of shipwreck. Rockets for this purpose should be at least two inches in interior diameter. The rod should be of the same length and thickness as a rocket of half this caliber. To this rod is tied the cord, which must be light, and yet strong, and when the rocket is fired, the string should be arranged loose, so that no impediment is experienced in the flight of the rocket.

The applications of the succouring rocket are two in particular: viz. In case a seaman should fall overboard, and in case of shipwreck; in the former, to throw a cord to some distance, and in the latter, to convey a cord from the ship to the shore, should a vessel be stranded on a beach. Several methods have been proposed for the same purpose, namely, that of conveying a line or rope to shore, when the surf is too high for a small boat to live in it.

The invention of lieut. Bell, described in the Annales des Arts et Manufactures, and in the Archives des Découvertes, ii, 120, is designed for a similar purpose as the succouring rocket. Mr. Bell's invention consists simply in throwing a rope from a vessel by means of a mortar, attaching it to a shell, in order to make a communication from a vessel in danger to the shore. For this contrivance, he received one hundred guineas.

Several experiments were made with it, which were satisfactory.

In the essays, published by Mr. Fulton, a contrivance of this kind is suggested, using, however, an instrument similar to a harpoon, to which a rope is attached. This harpoon is thrown by a long gun. It is calculated, also, as the harpoon for this purpose is furnished with several barbs, to pierce and secure an enemy's vessel.

Sec. XXX. Of the Greek Fire.

It is not known precisely what the composition of the Greek fire was. It was invented by Callinicus of Hellipolis, a town in Syria, who used it with so much skill and effect during a naval engagement, that he destroyed a whole fleet belonging to the enemy, in which were embarked thirty thousand men. It is defined to be a sort of artificial fire, which insinuates itself beyond the surface of the sea, and which burns with increased violence, when it mixes with water. Its directions are contrary to the course of natural fire; for the flames, we are told, will spread themselves downwards, to the right or left, agreeably to the moment that is given.

It was used in the year 1679, and was known and used in 1291. It was certainly liquid, and employed in many different ways; but, chiefly, on board ships, being thrown from large engines on the ships of the enemy. This fire was sometimes kindled in particular vessels, which might be called fire-ships, and which were introduced among a hostile fleet. Sometimes it was put into jars and other vessels, which were thrown at the enemy by means of projectile machines; and sometimes it was squirted by soldiers from hand-engines, or, as it appears, blown through pipes. This fire was discharged from the fore part of ships, by a machine constructed of copper and iron, the extremity of which resembled the open mouth and jaws of a lion or other animal. They were painted, and even gilded, and, it appears, were capable of projecting the fire to a great distance.

Professor Beckman, who examined all the ancient authors respecting the Greek fire, expressly says, that the machines which the ancients employed to throw this fire were spouting engines. He also observes (History of Invent. iv, p. 85) that "John Cameniata, speaking of his native city, Thessalonica, which was taken by the Saracens in the year 901, says, that the enemy threw fire into the wooden works of the besieged, which was blown into them by means of tubes, and thrown from other vessels. This passage, which I do not find quoted in any of the works that treat on the Greek fire, proves, that the Greeks, in the beginning of the tenth century, were no longer the only people acquainted with the art of preparing this fire, the precurser of our gunpowder. The Emperor Leo, who about the same period wrote his art of war, recommends such engines, with a metal covering, to be constructed in the fore part of ships; and he twice afterwards mentions engines for throwing out Greek fire. In the east, one may easily have conceived the idea of loading some kind of pump with the Greek fire; as the use of a forcing pump for extinguishing fires was long known there before the invention of Callinicus."

Writers differ considerably as to the composition of Greek fire, properly so called, as there were many preparations, some hundred years after the discovery, which went under the name of Greek fire. Certain it is, that the Greeks had a knowledge of a very highly combustible preparation, which water would not extinguish, and which, from its nature, must have had the property of decomposing water itself, or possessed so much oxygen, as to support the combustion of the inflammable substances, even in contact with water.

Mr. Parke, (Chem. Catechism, p. 465), speaking of some of the uses of nitre or saltpetre, says, that "for the same purposes it was used by the ancients in that destructive composition of antiquity, the Greek fire. Sulphur, rosin, camphor, and other combustibles, were melted with it, and in this melted mass, woollen cords were dipped, which were afterwards rolled up for use. These balls being set on fire were thrown into the tents, &c. of the enemy, and as the combustibles were furnished with a constant supply of oxygen from the nitre, nothing could extinguish them." He also observes: "For many centuries, the method of making this dreadful article of destruction was lost; but it has just been discovered by the librarian of the elector of Bavaria, who has found a very old latin manuscript, which contains directions for preparing it."

It appears, however, that it could only be extinguished by urine, sand, &c. James (Mil. Dic. p. 329) says, "it is composed, or made up of naphtha, sulphur, bitumen, gum, and pitch, and it can only be extinguished by vinegar, mixed with urine and sand, or with undressed leather and green hides."

The author of a French work, Œuvres Militaires, says, that a powerful composition, which is not extinguishable with water, may be made of the following substances: viz. pitch, rosin, tallow, camphor, turpentine, saltpetre, liquid varnish, oil of sulphur, linseed, rock oil, flax, and charcoal finely pulverized. The whole is melted together and boiled, and before it grows cold, quicklime in powder is added. It is said to be susceptible of the most subtile and destructive fire.

Bertrandon de la Brocquiere, who was in Palestine in 1432, as counsellor to the Duke of Burgundy, observes, that the Moors were then in possession of the Greek fire. He was present at Barrat, during one of the Moorish celebrations. "It began," says he, "in the evening at sun set. Numerous companies, scattered here and there, were singing and uttering loud cries. While this was passing, the cannon of the castle were fired, and the people of the town launched into the air, 'bien hault et bien loing, une maniére de feu plus gros fallot que je veisse oncques allume.' They told me, they made use of such at sea, to set fire to the sails of an enemy's vessel. It seems to me, that as it is a thing easy to be made, and at a little expense, it may be equally well employed to burn a camp or a thatched village, or in an engagement with cavalry, to frighten their horses.

"Curious to know its composition, I sent the servant of my host to the person who made this fire, and requested him to teach me this method. He returned for answer, that he dared not, for that he should run great danger, were it known; but as there is nothing a Moor will not do for money, I offered him a ducat, which quieted his fears, and he taught me all he knew, and even gave me the moulds in wood, with the other ingredients, which I have brought to France."

Although La Brocquiere may have brought the secret to Europe, yet it does not appear to have been used.

We may justly conclude, that the present gunpowder possesses superior advantages to the Greek fire, and some authors, as Ruggeri, are of opinion, that the account we have of it, that of its fire descending, and the like, are exaggerated.

Porta, (Magie Naturelle), in treating of this subject, observes, that the Greek fire was composed of the charcoal of willow, salt, burnt brandy, sulphur, pitch, frankincense, flax, and camphor, and that camphor alone has the effect of burning in water. He remarks also, that, when Constantinople was attacked, the emperor Leon burnt the vessels, or boats, to the number of 1800, by means of the Greek fire. The Journal des Savants, 1676, p. 148, speaks of the origin and use of the same fire.

In 1249, at the siege of Damietta, the French experienced the fatal effects of it. The Journal des Savants for 1666, mentions a machine, which, when applied against a vessel, communicates fire to it immediately, without injuring the person who uses it. In the French papers for 1797, M. Chevalier announced, that he had invented an inextinguishable incendiary fuse, which is thrown by fire arms, and calculated to set fire to the rigging of ships. In 1759, Dr. Dupré published in the French Journals, that he had invented a composition, which had the same properties and effects as the ancient Greek fire, and that he possessed the means of extinguishing it. An experiment was made at Versailles to the satisfaction of all, and the secret was purchased by Louis XV. The Rev. J. P. Coste, in 1794, laid before the French national convention, a new invention, for the purpose of war, consisting of a carcass composition, which nothing could extinguish, and which resembled in that respect the Greek fire.

Thevenot (Travels in the Levant), says, that in the 52d year of the Hegira, (Anno Domini 672), Constantinople was besieged in the reign of Constantine Prognates, by Yesid, the son of Moavia, the first caliph of the family of the Ammiades; when the Greek emperor found himself so pressed, that he was almost reduced to despair. But the famous engineer, Callinicus, invented a kind of wild fire, which would burn under water, and by this means destroyed the whole fleet.

Gibbon (History of the Decline and Fall of the Roman Empire, vol. vii, p. 282), speaks also of the Greek fire, and observes, that the deliverance of Constantinople may be chiefly ascribed to it. It appears, that Callinicus, the inventor, deserted from the service of the Caliph to that of the Emperor; and Gibbon is of opinion, that this discovery or improvement of the military art, was fortunately reserved for the distressful period, when the degenerate Romans of the east were incapable of contending with the warlike enthusiasm and youthful vigour of the Saracens. He is of opinion, that little or no credit can be given to the Byzantine accounts, as to the composition of this fire; although, from their obscure and fallacious hints, it should seem that the principal ingredient was naphtha, a liquid bitumen which springs from the earth.[39] This was mixed with sulphur, and with the pitch, extracted from the evergreen firs, according to the testimony of Anna Commena, (Alexid, l. xiii, p. 383), and Leo, in the xixth chapter of his Tactics, speaks of the new invention.

Gibbon describes its effects much as we have stated, viz. that the fire was strong and obstinate, and was quickened by water; that sand, urine, and vinegar were the only agents that could damp its fury; that it was used for the annoyance of the enemy, both by sea and land, in battles or in sieges, and was either poured from the rampart in large boilers, or lanched into red-hot balls of stone and iron, or darted in arrows and javelins, twisted round with flax and tow, which had deeply imbibed the inflammable oil; that, at other times, it was deposited in fire ships, or blown through long tubes of copper, fixed on a prow of a galley; that its composition was kept secret at Constantinople, pretending that the knowledge of it came from an angel to the first and greatest of the Constantines, with a sacred injunction not to divulge it under any pretext, &c. He also observes, that, after it was kept secret above four hundred years, and to the end of the 11th century, the method of preparing it was stolen by the Mahometans, who employed it against the crusaders. A knight, it appears, who despised the swords and lances of the Saracens, relates, with heartfelt sincerity, his own fears, at the sight and sound of the mischievous engine, that discharged a torrent of the Greek fire, the feu Gregeois, as it is styled by the more early of the French writers. "It came flying through the air," says Gibbon, quoting Joinville, (Histoire de St. Louis) "like a winged long tailed dragon, about the thickness of a hogshead, with a report of thunder and the velocity of lightning; and the darkness of the night was dispelled by this deadly illumination. The use of the Greek, or as it might now be called, Saracen fire, was continued to the middle of the 14th century, when the scientific or casual compound of nitre, sulphur, and charcoal, effected a new revolution in the art of war, and the history of mankind."

Ramsay, our learned historian, (Universal History, vol. ii, p. 150), gives the same account of the Greek fire. Morse, in his Universal Geography, page 588, observes, that naphtha forms springs in Persia, and, when scattered on the sea, it burns, and the flame is often wafted to a great distance.

For remarks respecting the naphtha of Persia, and the universal fire of the followers of Zoroaster, see the article on Naphtha. In naphtha districts, the quantity of inflammable air is so great, that it is used for fuel.

Since writing the above, we have examined Ruggeri, (Pyrotechnie Militaire, p. 289), and find nothing new. He states the composition of Greek fire, on the authority of others, to consist of naphtha, sulphur, bitumen, camphor, and petroleum; that it was invented by Callinicus, and employed against the Saracens as an incendiary; that Pliny, in his time, mentioned a combustible substance, which was thrown upon armed men, and burnt and destroyed them in the midst of the battle; that it was employed successfully by the successors of Constantine, and its composition was kept a state secret; that the Turks used it, or a composition of a similar nature, at the siege of Damieta, in 1249, forty-five years after the death of Roger Bacon; and, finally, that, when the composition and effects of gunpowder became known, the Greek fire, although it laid the foundation of the invention of gunpowder, was no longer in use, and the secret of the original preparation became lost. See Gunpowder.

Sec. XXXI. Of Mines and Mining.

A mine is a subterraneous passage, dug under the wall or rampart of a fortification, for the purpose of blowing it up by gunpowder; and mining is the art of accomplishing this effect.

The art of mining, having become one of the most essential parts of the attack and defence of places, should be well understood; and requires a perfect knowledge of heights, depths, breadths, and thicknesses; to judge perfectly of slopes and perpendiculars, whether they be such as are parallel to the horizon, or such as are visual; together with the true levels of all kinds of earth. To this may be added, a knowledge of rocks, clays, soil, &c. and the effect of gunpowder.

Mines were made long before the invention of gunpowder. The ancients made galleries, or underground passages, much in the same manner as the moderns, from without, under the walls of places, which they cut off from the foundation, and supported with strong props. The intervals were filled with all manner of combustibles, which, being set on fire, burnt their props, and the wall, being no longer supported, fell, by which a breach was made.

The besieged also made underground passages, from the town, under the besiegers' machines, by which they battered the walls, to destroy them, proving that necessity has been the inventress of mines.

The first mines we read of, since the invention of gunpowder, were made in 1487, by the Genoese, at the attack of Serezanella, a town in Florence. These, however, failed, and they were neglected, till Peter Navarro, being then engineer to the Genoese, and afterwards to the Spaniards, in 1503, against the French, at the siege of the castle del Ovo, at Naples, made a mine under the wall, and blew it up; in consequence of which the castle was taken by storm. Valliers says, that the engineer was Francis George, an Italian.

The place where the powder is lodged, is called the chamber of the mine, or fourneau, and the passage leading to the powder, is called the gallery. The line of the least resistance, is the line drawn from the centre of the chamber, perpendicular to the surface of the ground; and the excavation, called the crater, is the pit or hole, made by springing the mine.

Counter-mines are those made by the besieged, whereas mines are generally made by the besiegers. Both mines and counter-mines, are made in the same manner, and for like purposes, viz. to blow up their enemies and their works.

Galleries, made within the fortification, before the place is attacked, and from which several branches are carried to different places, are generally 4 and 4¹/₂ feet wide, and 5 or 5¹/₂ feet high. The earth is supported from falling in, by arches and walls, as they are to remain for a considerable time. But when mines are made to be used in a short time, then the galleries are but 3 or 3¹/₂ feet wide, and 5 feet high, and the earth is supported by wooden frames, or props.

The gallery being carried on to the place, where the powder is to be lodged, the miners make the chambers. This is generally of a cubical form, large enough to hold the wooden box, which contains the powder necessary for the charge. The box is lined with straw and sand bags, to prevent the powder from contracting dampness.

The chamber is sunk rather lower than the gallery, if the soil permits; but where water is to be apprehended, it must be made higher than the gallery; otherwise the besieged will let in the water, and spoil the mine.

The fire is communicated to the mine by a pipe, or hose, made of coarse cloth, whose diameter is about 1¹/₂ inches, called a saucisson, (for the filling of which, near half a pound of powder is allowed to every foot), extending from the chamber to the entrance of the gallery, to the end of which is fixed a match, that the miner who sets fire to it, may have time to retire before it reaches the chamber.

To prevent the powder from contracting any dampness, the saucisson is laid in a small trough, called an auget, made of boards 3¹/₂ inches broad, joined together lengthwise, with straw in it, and round the saucisson, with a wooden cover nailed upon it.

The quantity of powder, required to charge mines, depends upon the nature of the soil. That which is more tenacious, will require the greatest force to separate its parts. The density may be learned, comparatively speaking, by determining the specific gravity of each kind of soil. The requisites in mining may be ascertained by four simple problems, which relate to the nature of the soil, the diameter of the excavation, the line of least resistance, and the charge.

Table of the quantity of Gunpowder, to raise a cubic fathom of different kinds of Soil.

The gallery and chamber being ready to be loaded, a strong box of wood is made of the size and figure of the chamber, being about one-third or one-fourth larger than is required for containing the necessary quantity of powder. Against the sides and bottom of the box is put some straw, and this straw is covered over with empty sand bags, to prevent the powder from contracting any dampness. A hole is made in the side, next the gallery, near the bottom, for the saucisson to pass through, which is fixed to the middle of the bottom, by means of a wooden peg, to prevent its loosening from the powder, or to hinder the enemy (if he should reach the entrance) from being able to tear it out. This done, the powder is brought in sand bags, and thrown loosely in the box, and covered also with straw and sand bags. Upon this is put the cover of the box, pressed down very tight with strong props; and, to render them more secure, planks are also put above them, against the earth, and wedged in as fast as possible.

This done, the vacant spaces between the props are filled up with stones and dung, and rammed in the strongest manner. The least neglect in this work will considerably alter the effect of the mine. Then the auget, or small trough, is laid from the chamber to the entrance of the gallery, with some straw at the bottom; and the saucisson laid in it, with straw over it. Lastly, it must be shut with a wooden cover, nailed upon it. Great care must be taken in stopping up the gallery, not to press too hard upon the auget, for fear of spoiling the saucisson, which may hinder the powder from taking fire, and prevent the mine from springing. The gallery is stopped up with stones, earth and dung, well rammed, six or seven feet further from the chamber than the length of the line of the least resistance.[40]

Before closing this article, short as it is, compared with a full view of the subject, which belongs exclusively to engineering, we shall notice, from Belidor, the globe of compression in mines. If we imagine a large globe of earth, homogeneous in all its parts, and a certain quantity of powder lodged in its centre, so as to produce a proper effect without bursting the globe; by setting fire to the powder, it is evident that the explosion will act all round, to overcome the obstacles which oppose its motion; and as the particles of the earth are porous, they will compress each other in proportion as the flame increases, and the capacity of the chamber increases likewise: but the particles of the earth next to the chamber will communicate a part of their motion to those next to them, and those to their neighbours; and this communication will thus continue in a decreasing proportion, till the whole force of explosion is entirely spent; and the particles of earth beyond this term will remain in the same state as they were at first. The particles of earth, that have been acted upon by the force of explosion, will compose a globe, which Mr. Belidor calls the globe of compression. He observed, that, when a mine exploded, and threw up the ground over it, its action was, at the same time, felt in a circular direction, throughout the surrounding ground, to a distance at least equal to the oblique line drawn from the centre of inflammation to the edge of the funnel.

Mines and counter-mines are now called offensive and defensive mines. The hole made by the explosion is called the entonnoir, crater, or funnel.

In the system of counter-mines, we have the magistral gallery, or gallery of the counterscarp, which is that extended below the covered way, from which branches are pushed to overthrow the works and batteries of the beseiger, that crown it; the enveloping gallery that communicates with the other passages, called the galleries of communication, and is nearly parallel with the first at the distance of from forty to sixty yards. Other galleries are pushed forward, leaving the enveloping gallery, projecting at least thirty yards, and having spaces between them of about fifty yards in width; so that the enemy's miner, whose work may be heard under ground about thirty yards, may not pass between any two of them without being discovered. These are called listening galleries. It may be observed, that, from these galleries, branches are carried forward to establish chambers under the works of the enemy. Those who wish to acquire information on this, and other subjects, connected with attack and defence, and on some branches of engineering, would do well to consult the French work of Bousmard.

There are likewise small mines called Fougasses, used in the defence of field works. They are seldom more than ten feet beneath the surface, and are placed at the expected points of attack, usually nine feet from the salient angles, and without the counterscarp. The chest of powder and the saucisson are placed as usual. Barrels or casks and even grenades are used.

Sec. XXXII. Of the Means of Increasing the Strength of Gunpowder for Mining.

We mentioned, in the article on gunpowder, that quicklime had the effect of increasing its strength. It has been suggested, to employ quicklime, for this purpose, when gunpowder is used in mining.

Bottée and Riffault (Traité de l'art de Fabriquer la Poudre à canon, p. 301) have given the result of some experiments on this subject, which we purpose to notice. These experiments, however, are not satisfactory on this head.

Dr. Baine, a physician of Foxano, in Tuscany, was the first who announced the fact, that quicklime would increase the explosive effect of gunpowder. The increase he states to be one-third. The proportions are, twenty-three grammes of quicklime, and one kilogramme of powder.[41] The quicklime is powdered, and mixed with the gunpowder.

Various experiments were made, with the eprouvette of Regnier, which did not establish the truth of Dr. Baine's assertion. The Tuscan hunters use gunpowder mixed with lime.

The experiments were made by M. L. Maitre and colonel Charbonel. They employed pure dry powder, dry powder mixed with quicklime, moist powder pure, and moist powder mixed with lime. The object of these experiments was to ascertain, if the presence of quicklime added to the force of powder; either as a fourth component part and acting chemically, or by absorbing the moisture which the powder contains.

The charge of each was three ounces.

The result of the experiments is thus given:

It has been asserted, that the force of gunpowder is increased by water, alcohol, and ether, in consequence of the great expansibility of these fluids; but, according to the experiments of Bottée and Riffault, the range of the ball was much less when the three fluids were used successively, than when the dry and pure gunpowder alone was employed. We are informed by a gentleman, who saw the experiment made, that when gunpowder is mixed with an equal weight of fine saw dust, and fired, it will give the same range to a ball as the same weight of unmixed powder.