Chapter XVI: TECHNOLOGY.--Action of Caustic Soda on Wood.--By M.H (4)

3d. Unless we have a fleet for every harbor, it would be impossible to depend upon this kind of defense, as the enemy would select whichever harbor he found least prepared to receive him. It would be of vital importance that we defend every harbor of importance, as a neglect to do so would be like locking some of our doors and leaving the others open to the burglars.

4th. It might be thought that we could send our fleet to intercept the enemy or blockade him in his own ports, but this has been found impracticable. Large fleets can readily escape from blockaded harbors, or elude each other on the high seas, and any such scheme implies that we are much stronger on the ocean than the enemy, which is very far from the case. To build a navy that would overmatch that of Great Britain alone would not only cost untold millions, but it would require many years for its accomplishment; and even if this were done, there would be nothing unusual in an alliance of two or more powerful nations, which would leave us again in the minority. _Fleets, then, cannot be relied on for permanent defense_.

Again, it may be said that we have millions of the bravest soldiers in the world who could be assembled and placed under arms at a few days' notice. This kind of defense would also prove a delusion, for a hundred acres of soldiers armed with rifles and field artillery would be powerless to drive away even the smallest ironclad or stop a single projectile from one. In fact, neither of these plans, nor both together, would be much more effective than the windmills and proclamations which Irving humorously describes as the means adopted by the early Dutch governors of New York to defend that city against the Swedes and Yankees.

Having considered some of the means of defense that will _not_ answer the purpose, we may inquire what means _will be_ effective. And here it should be noted that our defenses should be so effective as not only to be reasonably safe, but to be so recognized by all nations, and thus discourage, if not actually prevent, an attack upon our coast.

In the first place, we must have heavy guns in such numbers and of such sizes as to overmatch those of any fleet likely to attack us. These guns must be securely mounted, so as to be worked with facility and accuracy, and they must be protected from the enemy's projectiles at least as securely as his guns are from ours. Merely placing ourselves on equal terms with the enemy, as in case of a duel or an ancient knight's tournament, will not answer, first, because such a state of things would invite rather than discourage attack, and secondly, because the enemy would have vastly more to gain by success and vastly less to lose by failure than we would. This can be accomplished much easier than is generally supposed, either by earthen parapets of sufficient thickness or by iron turrets or casements. It is evident that the weight of metal used in these structures may be vastly greater than could be carried on shipboard. Great weight of metal is no objection on land, but, aside from its cost, is a positive advantage. This is evident when we consider the enormous quantity of energy stored in the larger projectiles moving at high velocities. For example, we often hear of the sixteen inch rifle whose projectile weighs about one ton, and this enormous mass projected at a velocity of 2,000 feet per second would have a kinetic energy of 60,000 foot tons, or it would strike a blow equal to that of ten locomotives of 50 tons each running at 60 miles an hour and striking a solid wall. Any structure designed to resist such ponderous blows must, therefore, have enormous weight, or it will be overturned or driven bodily from its foundations. If the armor itself is not thick enough to give the required weight as well as resistance to penetration, the additional stability must be supplied by re-enforcing it with heavy masses of metal or masonry. It is evident, therefore, that _quality_ of metal is less important than _quantity_, and that so long as it is sufficiently tough to resist fracture, a soft, cheap metal, like wrought iron or low steel, is better adapted for permanent works than any of the fancy kinds of armor that have been tested for naval purposes. As an illustration of this, we may compare compound or steel-faced armor with wrought iron as follows: The best of the former offers only about one-third greater resistance to penetration than the latter, or 12 inches of compound armor may equal 16 inches of wrought iron, but the cost per ton is nearly double; so that by using wrought iron we may have double the thickness, or 24 inches, which would give more than double the resistance to penetration, in addition to giving double the stability against overturning or being driven bodily out of place. But our guns may be reasonably well protected by earthen parapets without any expensive armor by so mounting them that when fired they will recoil downward or to one side, so as to come below the parapet for loading. This method of mounting is called the disappearing principle, and has been suggested by many engineers, some of whose designs date back more than one hundred years. We may also mount our guns in deep pits, where they will be covered from the enemy's guns, and fire them at high elevation, so that the shell will fall from a great height and penetrate the decks of the enemy's ships. This is known as mortar firing, but the modern ordnance used for this purpose is more of a howitzer than a mortar, being simply short rifled pieces arranged for breech loading. All our batteries should, of course, be as far from the city or other object to be protected as possible, to prevent the enemy from firing over and beyond the batteries into the city.

But, with all these precautions, the enemy might put on all steam and run by us either at night or in a dense fog, and we must have some means of holding him under the fire of our guns until his ships can be disabled or driven away. This object is sought to be accomplished by the use of torpedoes anchored in the channels and under the fire of our guns, so that they cannot be removed by the enemy. These torpedoes are generally exploded by electricity from batteries located in casements on shore, these casements being connected with the torpedoes by submarine cables. It is easy to see how the torpedo may be so arranged that when struck by a ship the electric current will be closed, and, if the battery on shore is connected at the same instant, an explosion will take place; on the other hand, if the battery on shore is disconnected a friendly ship may pass in safety over the torpedoes. Many ingenious contrivances have also been devised by which the torpedo may be made to signal back to the shore station either that it has been struck or that it is in good order for service, in case the enemy should undertake to run over it. One simple plan for this is to have a small telephone in the torpedo with some loose buckshot on the diaphragm, which is placed in a horizontal position, and will be slightly tilted as the torpedo is moved about by the waves. By connecting the shore end of the cable with a telephone receiver, the rolling of the shot may be distinctly heard if the torpedo is floating properly, but if sunk at its moorings, or if the cable is broken, no sound will be heard.

The use of torpedoes involves the use of both electricity and high explosives, and a careful study based upon actual experiments has been carried on for many years, by the engineers and naval officers in all civilized countries. Some of these experiments have supplied interesting and useful data, for the use of the agents in question, for various industrial purposes.

Another form of torpedo is that known as the locomotive torpedo, of which there are several kinds; some are propelled by liquid carbonic acid, which is carried in a strong tank and acts through a compact engine in driving the propeller. One of these is steered by electricity from the shore, and is known as the Lay-Haight torpedo, and can run twenty-five miles per hour. The Whitehead torpedo is also propelled by liquid carbonic acid, but is not steered from shore. Its depth is regulated by an automatic device actuated by the pressure of the water. The Howell torpedo is driven by a heavy fly wheel which is set in rapid rotation just before the torpedo is launched. It has but a short range and is intended for launching from ships. Another torpedo is propelled and steered from shore by rapidly pulling out of it two fine steel wires which, in unwinding, drive the twin screw propellers. This is the Brennan torpedo. The Sims-Edison torpedo is both propelled and steered by electricity from the shore, transmitted to a motor and steering relay in the torpedo by an insulated cable. This cable has two cores and is paid out by the torpedo as it travels through the water just as a spider pays out its web. The cable is about half an inch in diameter and two miles long, and the torpedo can be driven at about eighteen miles per hour with a current of thirty amperes and 1,800 volts pressure.

Still another auxiliary weapon of defense is the dynamite gun, or rather, a pneumatic gun, that throws long projectiles carrying from 250 to 450 pounds of dynamite, to a distance of about two miles. The shells are arranged to explode soon after striking the water, by an ingenious battery that ignites the fuse as soon as the salt water enters it. The gun, which is known as the Zalinski gun, is some sixty feet long and fifteen inches in caliber, the compressed air being suddenly admitted to it from the reservoirs at any desired pressure by a special form of valve that regulates the range. These guns are to be mounted in deep pits and fired at somewhat higher elevations than ordinary guns, but it has great accuracy within reasonable limits of range.

FIELD FORTIFICATIONS.

In field fortification an enormous quantity of work was done during our last war. Washington, Richmond, Nashville, Petersburg, Norfolk, New Berne, Plymouth, Vicksburg, and many other cities were elaborately fortified by field works which involved the handling of vast quantities of earth, and, where the opposing lines were near together, ditches, abbatis, ground torpedoes, and wire entanglements were freely used. In some cases the same ground was fortified in succession by both armies, so that the total amount of work expended, in this way, would have built several hundred miles of railway. Around Richmond and Petersburg alone the development of field works was far greater than Wellington's celebrated lines at Torres Vedras. In all future wars, when large armies are opposed to each other, it is probable that field works will play even a more important part than in the past. The great advantage of such works, since the introduction of the deadly breech loading rifles and machine guns, was shown at Plevna, where the Russians were almost annihilated in attempting to capture the Turkish intrenchments.

SIEGES.

It is not proposed to go into historical or other details of this branch of the subject, but to give in a condensed form some account of siege operations. According to the text books, the first thing to be done, if possible, in case of a regular siege, is to "invest" the fortress. This is done by surrounding it as quickly as possible with a continuous line of troops, who speedily intrench themselves and mount guns bearing outward on all lines of approach to the fortress, to prevent the enemy from sending in supplies or re-enforcements. As this line must be at considerable distance from the fort, it is usually quite long, and so is its name, for it is called the line of "Circumvallation." Inside of this line is then established a similar line facing toward the fort, to prevent sorties by the garrison. This line is called the line of "Countervallation," and should be as close to the fort as the range of its guns and the nature of the ground will permit. From this line the troops rush forward at night and open the trenches, beginning with what is called the first parallel, which should be so laid out as to envelop those parts of the fort which are to be made the special objects of attack. From this first parallel a number of zigzag trenches are started toward the fort and at proper intervals other parallels, batteries, and magazines are built; this method of approach being continued until the besieged fort is reached, or until such batteries can be brought to bear upon it as to breech the walls and allow the attacking troops to make an assault.

During these operations of course many precautions must be observed, both by the attacking and defending force, to annoy each other and to prevent surprise, and the work is mostly carried on under cover of the earth thrown from the trenches. These operations were supposed to occupy, under normal conditions, about forty-one days, or rather nights, as most of the work is done after dark, at the end of which time the fort should be reduced to such a condition that its commander, having exhausted all means of defense, would be justified in considering terms of surrender.

The _Theoretical Journal_ of the siege prescribes just what is to be done each day by both attack and defense up to the final catastrophe, and this somewhat discouraging outlook for the defenders was forcibly illustrated by the late Captain Derby, better known by the reading public as "John Phoenix," who, when a cadet, was called upon by Professor Mahan to explain how he would defend a fort, mounting a certain number of guns and garrisoned by a certain number of men, if besieged by an army of another assumed strength in men and guns, replied:

"I would immediately evacuate the fort and then besiege it and capture it again in forty-one days."

Of course the fallacy of this reasoning was in the fact that the besieging army is generally supposed to be four or five times as large as the garrison of the fort; the primary object of forts being to enable a small force to hold a position, at least for a time, against a much larger force of the enemy.

Sieges have changed with the development of engines of war, from the rude and muscular efforts of personal prowess like that described in Ivanhoe, where the Black Knight cuts his way through the barriers with his battle axe, to such sieges as those at Vicksburg, Petersburg, and Plevna, where the individual counted for very little, and the results depended upon the combined efforts of large numbers of men and systematic siege operations. It should also be noticed that modern sieges are not necessarily hampered by the rules laid down in text books, but vary from them according to circumstances.

For example, many sieges have been carried to successful issues without completely investing or surrounding the fortress. This was the case at Petersburg, where General Lee was entirely free to move out, or receive supplies and re-enforcements up to the very last stages of the siege. In other cases, as at Fort Pulaski, Sumter, and Macon, the breeching batteries were established at very much greater distances than ever before attempted, and the preliminary siege operations were very much abbreviated and some of them omitted altogether. This is not an argument against having well defined rules and principles, but it shows that the engineer must be prepared to cut loose from old rules and customs whenever the changed state of circumstances requires different treatment.

MILITARY BRIDGES.

In the movement of armies, especially on long marches in the enemy's country, one of the greatest difficulties to be overcome is the crossing of streams, and this is usually done by means of portable bridges. These may be built of light trestles with adjustable legs to suit the different depths, or of wooden or canvas boats supporting a light roadway wide enough for a single line of ordinary wagons or artillery carriages. The materials for these bridges, which are known as Ponton Bridges, are loaded upon wagons and accompany the army on its marches, and when required for use the bridge is rapidly put together, piece by piece, in accordance with fixed rules, which constitute, in fact, a regular drill. The wooden boats are quite heavy and are used for heavy traffic, but for light work, as, for example, to accompany the rapid movements of the cavalry, boats made of heavy canvas, stretched upon light wooden frames, that are put together on the spot, are used.

During Gen. Sherman's memorable Georgia campaign and march to the sea, over three miles of Ponton bridges were built in crossing the numerous streams met with, and nearly two miles of trestle bridges. In Gen. Grant's Wilderness campaign the engineers built not less than thirty-eight bridges between the Rappahannock and the James Rivers, these bridges aggregating over 6,600 feet in length. Under favorable circumstances such bridges can be built at the rate of 200 to 300 feet per hour, and they can be taken up at a still more rapid rate. When there is no bridge train at hand the engineer is obliged to use such improvised materials as he can get; buildings are torn down to get plank and trees are cut to make the frame. Sometimes single stringers will answer, but if a greater length of bridge is required it may be supported on piles or trestles, or in deep water on rafts of logs or casks. But the heavy traffic of armies, operating at some distance from their bases, must be transported by rail, and the building of railway bridges or rebuilding those destroyed by the enemy is an important duty of the engineer. On the Potomac Creek, in Virginia, a trestle bridge 80 feet high and 400 feet long was built in nine working days, from timber out of the neighborhood. Another bridge across the Etowah River, in Georgia, was built in Gen. Sherman's campaign, and a similar bridge was also built over the Chattahoochee.

SURVEYS AND EXPLORATIONS.

For more than half a century before the building of the great Pacific railways, engineer officers were engaged in making surveys and explorations in the great unknown country west of the Mississippi River, and the final map of that country was literally covered with a network of trails made by them. Several of these officers lost their lives in such expeditions, while others lived to become more famous as commanders during the great rebellion. Generals Kearney, J.E. Johnston, Pope, Warren, Fremont and Parke, and Colonels Long, Bache, Emory, Whipple, Woodruff and Simpson, Captains Warner, Stansbury, Gunnison and many other officers, generally in their younger days, contributed their quota to the geographical knowledge of the country, and made possible the wonderful network of railways guarded by military posts that has followed their footsteps. Their reports fill twelve large quarto volumes.

BOUNDARY AND LAKE SURVEYS.

The astronomical location of the boundaries of the several States and Territories, as well as of the United States, is a duty frequently required of the engineer officer, and such a survey between this country and Mexico is now in progress. The entire line of the 49th parallel of latitude from the Lake of the Woods to the Pacific Ocean, which forms our northern boundary, was located a few years ago by a joint commission of English and United States engineers, and monuments were established at short intervals over its entire length.

A careful geodetic and hydrographic survey of the Great Northern Lakes, including every harbor upon them and the rivers connecting them, was carried on for many years and was finally completed some ten years ago. Maps and charts of these surveys are published from time to time for use of pilots navigating these waters.

Not only are the duties of the military engineer similar in many respects to those of the civil engineer, but there are many instances in which the duties of one branch of the profession have been performed by members of the other branch, quite as efficiently as though they had been performed by engineers specially educated for the purpose. During the late civil war there were many illustrations of this, all showing that an ingenious engineer can readily adapt himself to circumstances entirely different from those to which he has been accustomed. A very good example of this occurred in the Red River expedition of General Banks and Admiral Porter. In that memorable but disastrous campaign an army accompanied by a fleet of transports and light draught gunboats, sometimes called "tin clads" because some parts of them were covered with boiler plate to stop the bullets of the enemy, ascended the Red River in Louisiana; but the advance having been checked and a retreat commenced, it was found that the river had fallen to such a low state that the fleet was caught above the rapids near Alexandria, and it would in all probability have been a complete loss had it not been for the timely application of engineering skill by Lieut. Col. Joseph Bailey, a civil engineer from Wisconsin, who built a temporary dam across the river below the rapids and floated out the entire fleet. This dam was over 750 feet long and in connection with some auxiliary dams raised the water level some 61/2 feet. It was built under many difficulties, but by the skill and ability of the engineer and the co-operation of the troops it was completed in ten days. Another case was at the siege of Petersburg, Va., where Lieut. Col. Pleasants, a Pennsylvania coal miner, ran a gallery from our lines, under the rebel battery, some 500 feet distant, and blew it entirely out of existence. The mine contained four tons of powder and produced a crater 200 feet by 50 feet and 25 feet deep, and was completed in one month. The sequel to this was to be an attack on the enemy's line through the gap made by the explosion, and such an attack properly followed up would doubtless have had a marked effect in shortening the duration of the war, but this attack was so badly managed that it utterly failed and caused a severe loss to our own army. The mine itself, however, was a great success and produced a decided moral effect on both sides which lasted until the end of the war.

It may be out of place to digress a moment to illustrate the moral effect of such a convulsion. Several weeks after this great mine explosion, the 18th Army Corps, to which I then belonged, was holding a line of works recently captured from the rebels, about six miles from Richmond, when one night the colonel commanding Fort Harrison, a large field work forming a part of this line, came down to headquarters and reported that some old Pennsylvania coal miners in his command had heard mining going on under the fort. As the nearest part of the enemy's line was some 400 yards from the fort, I was quite certain that they could not have run a gallery that distance in the time that had elapsed since we occupied the work, but there was of course the possibility that the mine had been partly built beforehand so as to be ready in just such a case as had arisen, viz., the capture of the fort by our troops. I therefore went with the colonel up to the fort to listen for the mining operations, and got the men who claimed to have heard the subterranean noises, down in the bottom of the ditch of the fort, which was ten feet deep, and at the angles formed a fairly good listening gallery, but nothing unusual could be heard. I therefore made arrangements to sink a line of pits in the bottom of the ditch, something like ordinary wells; the bottoms of these pits to be finally connected by a horizontal gallery which would envelop the fort and enable us to hear the enemy and blow him up, before he could get under the fort. Although the commanding officer of that fort was as brave an officer as the war developed, he would not keep his men in the fort after dark, but withdrew them quietly to the flanks of the work, where they not only would be safe from an explosion, but would be ready to fall upon the enemy in case he should blow up the fort and rush in to capture the line, as our troops had attempted to do at Petersburg. No explosion took place, however, and after our countermining work was completed, the garrison became reassured and remained in the fort at night as well as in day time. A few months later, when the enemy was driven from his lines, I went through his works to see whether any mining had been attempted, and found that a gallery leading toward Fort Harrison had been carried quite a distance, but was still incomplete, and it is barely possible that the old miners were right, after all, in thinking that they could hear the sound of the pick, although the distance was almost too great to make this theory very probable.

Still another illustration of the way in which civil engineers can make themselves extremely useful in military operations was the wonderful system of military railways, or railways operated for military purposes, that formed complete lines of transportation for the armies and their enormous quantities of supplies and munitions, more especially those in the West and Southwest. Construction trains were organized in the most complete style, and when a piece of track or a number of bridges were destroyed by the enemy, they would be rebuilt so rapidly that our trains would hardly seem to be delayed by it. The trains carried spare rails, ties, and bridges of various lengths ready to put up, and they also carried the necessary rolling stock and tools for destroying the roads and bridges of the enemy. So expert had this construction corps become that the enemy was ready to believe almost any statement in regard to it. General Sherman tells of an instance where it was proposed to blow up a tunnel, to check his "March to the Sea," when one of the men objected, saying it was of no use, for Sherman had a duplicate tunnel in his train.

Although this is not a sermon, it may not be out of place to point out a few qualifications common to all engineers, for they all deal more or less with the same materials and forces and employ similar methods of investigation and construction. Wood, iron, steel, copper and stone and their compounds are the materials of the civil, mining, mechanical and electrical, as well as of the military engineers. They all deal with the forces of gravitation, cohesion, inertia and chemical affinity. They all require skill, intelligence, industry, confidence, accuracy, thoroughness, ingenuity and, beyond all, sound judgment. Wanting in any one of these qualifications, an engineer is more or less disqualified for important work. It is said that a distinguished engineer was always afraid to cross his own bridges, although built in the most thorough and approved manner. He was deficient in confidence. Another engineer distinguished for his mathematical attainments built a bridge which promptly collapsed at the first opportunity. On overhauling his computations he ejaculated somewhat forcibly, "That confounded minus sign! It should have been plus." He was deficient in sound judgment, or what is sometimes called "horse sense."

Another and more common defect in young engineers is a want of thoroughness. It is generally best to go to the bottom of a question at first and keep at it until it is thoroughly and fully completed. Confucius says, "If thou hast aught to do, first consider, second act, third let the soul resume her tranquillity." Those who begin a great many things and never fully complete them lose a great deal of valuable time, but do very little valuable work. The way to avoid this difficulty is to be cautious about beginning things, but when once started don't leave it until you are satisfied to leave it for good. There is an Arabian saying, "Never undertake _all_ you can do, for he who undertakes _all_ he can do will frequently undertake _more_ than he can do."

Another common error is extravagance. On the plea that "the best is always the cheapest," and to be sure of a large factor of safety, or as the late Mr. Holley called it a "factor of ignorance," without much trouble to themselves, some engineers use more or better materials than the work requires, and thus greatly increase the cost without any corresponding advantage. Almost any engineer can do almost anything in the way of engineering if not limited by the cost, but the man who knows just what materials to use and how to use them so that they will answer the purpose as to strength and durability can save his own salary to his employer many times over by simply omitting unnecessary expense.

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HOW MECHANICAL RUBBER GOODS ARE MADE.

While the manufacture of rubber goods is in no sense a secret industry, the majority of buyers and users of such goods have never stepped inside of a rubber mill, and many have very crude ideas as to how the goods are made up. In ordinary garden hose, for instance, the process is as follows: The inner tubing is made of a strip of rubber fifty feet in length, which is laid on a long zinc-covered table and its edges drawn together over a hose pole. The cover, which is of what is called "friction," that is cloth with rubber forced through its meshes, comes to the hose maker in strips, cut on the bias, which are wound around the outside of the tube and adhere tightly to it. The hose pole is then put in something like a fifty foot lathe, and while the pole revolves slowly, it is tightly wrapped with strips of cloth, in order that it may not get out of shape while undergoing the process of vulcanizing. When a number of these hose poles have been covered in this way they are laid in a pan set on trucks and are then run into a long boiler, shut in, and live steam is turned on. When the goods are cured steam is blown off, the vulcanizer opened and the cloths are removed. The hose is then slipped off the pole by forcing air from a compressor between the rubber and the hose pole. This, of course, is what is known as hose that has a seam in it.

For seamless hose the tube is made in a tubing machine and slipped upon the hose pole by reversing the process that is used in removing hose by air compression. In other words, a knot is tied in one end of the fifty foot tube and the other end is placed against the hose pole and being carefully inflated with air it is slipped on without the least trouble. For various kinds of hose the processes vary, and there are machines for winding with wire and intricate processes for the heavy grades of suction hose, etc. For steam hose, brewers', and acid hose, special resisting compounds are used, that as a rule are the secrets of the various manufacturers. Cotton hose is woven through machines expressly designed for that purpose, and afterward has a half-cured rubber tube drawn through it. One end is then securely stopped up and the other end forced on a cone through which steam is introduced to the inside of the hose, forcing the rubber against the cotton cover, finishing the cure and fixing it firmly in its place.

CORRUGATED MATTING.

After the mixing of the compound and the calendering, that is the spreading it in sheets, the great roll of rubber and cloth that is to be made into corrugated matting is sent to the pressman. Here it is hung in a rack and fifteen or twenty feet of it drawn between the plates of the huge hydraulic steam press. The bottom plate of this press is grooved its whole length, so that when the upper platen is let down the plain sheet of rubber is forced into the grooves and the corrugations are formed. While in that position steam is let into the upper and lower platens and the matting is cured. After it has been in there the proper time, cold water is let into the press, it is cooled off, and the upper platen being raised, it is ready to come out. A simple device for loosening the matting from the grooves into which it has been forced is a long steel rod, with a handle on one hand like an auger handle, which, being introduced under the edge and twisted, allows the air to enter with it and releases it from the mould.

PACKING.

Sheet packing is often times made in a press, like corrugated matting. The varieties, however, known as gum core have to go through a different process. Usually a core is squirted through a tube machine and the outside covering of jute or cotton, or whatever the fabric may be, is put on by a braider or is wrapped about it somewhat after the manner of the old fashioned cloth-wrapped tubing. The fabric is either treated with some heat-resisting mixture or something that is a lubricant, plumbago and oil being the compound. Other packings are made from the ends of belts cut out in a circular form and treated with a lubricant. There are scores of styles that make special claims for excellences that are made in a variety of ways, but as a rule the general system as outlined above is followed.

JAR RINGS.

The old fashioned way of making jar rings was first to take a large mandrel and wrap it around with a sheet of compounded rubber until the thickness of the ring was secured. It was then held in place by a further wrapping of cloth, vulcanized, put in a lathe and cut up into rings by hand. That manner of procedure, however, was too slow, and it is to-day done almost wholly by machinery. For example, the rubber is squirted out of a mammoth tubing machine in the shape of a huge tube, then slipped on a mandrel and vulcanized. It is then put in an automatic lathe and revolving swiftly is brought against a sharp knife blade which cuts ring after ring until the whole is consumed, without any handling or watching.--_India Rubber World_.

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HOW ENAMELED LETTERS ARE MADE.

The following is a description of a brief visit by a representative of the _Journal of Decorative Art_ to the new factory of the Patent Letter and Enamel Company, Ltd., situate in the East End of London.

The company have recently secured a large freehold plot in the center of the East End of London, and have built for themselves a most commodious and spacious factory, some hundreds of feet in length, all on one floor, and commanded from one end by the manager's office, from whence can be seen at a glance the entire premises.

The works are divided into two large compartments, and are lighted from the roof, ample provision being made for ventilation, and attention being given to those sanitary conditions which are, or should be, imperative on all well managed establishments.

We first explore the stockroom. Here are stored the numerous dies, of all sizes and shapes, which the company possess, varying in size from half an inch to twelve or sixteen inches. Here, too, is kept the large store of thin sheet copper out of which the letters are stamped. Our readers are familiar with the form or principle upon which these letters are made. It is simply a convex surface, the reverse side being concave, and being fixed on to the glass or other material with a white lead preparation. When these letters were first made, the practice was to cut or stamp them out in flat copper, and then to round or mould them by a second operation. Recent improvements in the machinery, however, have dispensed with this dual process, and the stamping and moulding is done in the one swift, sharp operation.

The process of making an enameled letter has four stages--stamping, enameling, firing, and filing. There are other and subsequent processes for elaborating, but those named are of the essence of the transaction.

STAMPING.

The stamping is done by means of presses, and is a very rapid and complete operation.

The operator takes a piece of the sheet copper, places it on the press, the lever descends, there is a sharp crunching, bursting sound, and in a time shorter than it has taken to describe, the letter is made, sharp and perfect in every way.

ENAMELING.

The letters are now taken charge of by a girl, who lays them out on a wire tray, the hollow side up, and paints them over with a thin mordant. While they are in this position, and before the mordant dries, they are taken on the gridiron-like tray to a kind of large box, which is full of the powdered enamel, and, holding the tray in her left hand, the girl takes a fine sieve full of the powder and dusts it over the letter, all superfluous powder falling through the open wirework and into the bin again, so that there is absolutely no waste.

FIRING.

The letters are now taken and placed carefully on thin iron disks or plates on the bench, where they remain until they are fired. It will be remembered that we said at the outset that the factory was divided into two large compartments, and it is into the second of these that we now go.

Here are ranged the series of furnaces which convert the copper and superincumbent enamel into one common body--fuse the one into the other. An unwary step soon warns us that we are too near the furnace, unless we want to run the risk of a premature cremation, and in the interests of the readers of this journal we step back to a respectful and proper distance, and watch the operations from afar.

There seems to be something innately picturesque about all furnaces and those who work about them. Whether it is the Rembrandt effects produced by the strong light and shade, or whether it is that the necessary use of the long iron instruments, such as all furnace workers employ, compels a certain dignity and grace of poise and action, we know not; but certain it is that the grace is there in a marked degree, and as we watched the men take their long-handled iron tongs and place in or lift out the plates of hot metal, we could not fail to be impressed with the charm of the physical action they displayed.

The disk containing the enameled letters is taken at the end of a long iron handle and carefully placed in a dome-shaped muffle. These muffles are all heated from the outside; that is, the fire is all round the chamber, but not in it, the fumes of the sulphur being destructive of the enamel if they are allowed to come into contact with it. So intense is the heat, however, that a muffle lasts only about nine days, and at the end of that time has to be renewed.

After the enamel is fused on to the copper, the disk is taken out and placed on a side slab, where it is allowed to cool.

This process is repeated on the front side of the letter, when all that remains to complete it is

THE FILING.

This is done by girls, who, with very fine files, rub off the edges and any protuberances which may be there. Every letter is subject to this operation, and all are turned out smooth and well finished.

Sometimes the letters are colored or further defined by the addition of a line, but the essentials are as we have already described.

BRUSHING OUT.

There are, however, one or two other operations of interest which we may notice. The company do not confine their exertions to the making of letters, various collateral developments having taken place which fill an important part in this scheme of work.

Of these, small tablets, containing advertisements or notices, such as we see in railway carriages, "Push after raising window," or "Close this door after you," or some legend pertaining to Brown's Soap or Robinson's Washing Powder. These are done by different processes, the transfer process, as used in the potteries, being employed, but the one most largely used is that of "brushing out," which is done by plates.

Let us suppose that the tablet shows white letters on a dark ground, the _modus operandi_ is as follows:

The tablet has been enameled, as already described, and is white. The operator now takes a dark enamel and spreads it evenly over the entire surface of the tablet. He, or she, now takes a stencil plate, of tinfoil, out of which the ground is cut, leaving the letter in the center.

This is carefully placed over the tablet and held tight with the left hand, while with the right hand he holds a fine brush, which he uses with a quick, sharp movement over the surface. This action readily removes the unfired color from the hard, glassy surface underneath, and leaves a white letter. This is fired, and is then complete.

Sometimes two and, it may be, three plates are necessary to complete the brushing out, as ties must be left, as in the case of ordinary stencils, and these have to be brushed out with additional plates. Two or three colors may be introduced by this process, but each separate color means separate firing. If the letters are dark on a light ground, the process is exactly the same, the stencil only being modified. In addition to the letters and tablets thus described, the company also undertake the production of large enameled signs, and to cope with the rapid expansion of this department of their work they are erecting special furnaces, to enable them to deal with any demand likely to be made upon them. The call for things permanent and washable in the way of advertising is on the increase, and the enameled plates made by the company is one of the most successful ways of meeting the demand.

* * * * *

BURNING BRICK WITH CRUDE OIL FUEL.

At the present time there is not the least reason why either wood, coal, or any other solid fuel should be used for the burning of brick. This style of burning brick belongs to a past age. The art of brickmaking has made tremendous progress during the past quarter of a century. It is no longer the art of the ignorant; brains, capital, experience, science, wide and general knowledge, must in these days be the property of the successful brick manufacturer. There are some such progressive brick manufacturers in Chicago, who use neither coal nor wood in the drying or burning of their clay products. Crude oil is the fuel which they employ, and with this fuel they obtain cheaper and better brick than do manufacturers who employ solid fuel. Some of these manufacturers have expressed themselves as preferring to quit the brick business rather than return to the use of wood or coal as fuel in brick burning.

This shows plainly that progress in our art, when it does come, comes to remain. It is true that crude oil for brick-burning purposes is not everywhere obtainable. But there is a fuel which is even better than crude oil, namely, fuel gas, and which can be produced and employed on any brick yard at a saving of seventy-five per cent. over coal or other solid fuel.

The Rose process for making fuel gas gives a water gas enriched by petroleum. Roughly, about half the cost of this gas as made at Bellefonte, Pa., was for oil. The gas cost 6.68c. per 1,000 cu. ft., with oil at 21/4c. a gallon. At double this price the gas would cost but 10c., and show that in practice, foot for foot, it equals natural gas.

Fuel gas means a larger investment of capital than does any of the other modes of brick burning, and is, therefore, not within the reach of the entire trade. The cost of appliances for burning brick with crude oil is not very large, and as all grate bars, iron frames, and doors can be dispensed with in the use of crude oil fuel, the cost of an oil-burning equipment is but little in excess of an equipment of grates, etc., for coal-burning kilns.

At works using small amounts of fuel, especially if cost of fuel bears but a small proportion to total cost of the manufactured product, oil will be in the future very largely used. It is clean, as compared with coal, can be easily handled, and when carefully used in small quantities, is safe. There are several methods of burning oil that are well adapted to the use of brick manufacturers and other fuel consumers.

The Pennsylvania Railroad made some very thorough experiments on the use of petroleum in their locomotives, and while the results obtained are reported to have been satisfactory, it was the opinion of those having the experiments in charge that the demand for the Pennsylvania Railroad alone, were it to change its locomotives from coal to oil, would consume all the surplus and send up the price of oil to a figure that would compel a return to coal.

It is true that production has enormously increased in the last three years, and the promise for the near future is that a high rate will be maintained. It is further true that the production of Russia has increased enormously, and will probably be larger this year than ever before. This Russian oil must go to markets and supply demands that have been met by American oil, and this will still further increase the amount of oil available for fuel purposes.

There is no doubt, therefore, that petroleum has a future for fuel uses. Many brick manufacturers are ready to use it, notwithstanding the possibility of an advance in its cost.

While there are some objections to the use of petroleum as a fuel, growing chiefly out of the risk attending its storage and conveyance to the point of consumption, it is undoubtedly true that the chief objection is the fear that with the increased demand that would follow any extended use for this purpose would come an increase in price that would make its continued use too expensive.

Just four years ago, when the fuel oil industry was first projected, it was cried down because, as its enemies claimed, there was not enough oil fuel to be obtained in America to supply the New York City factories alone, to say nothing of other territory, and because of the high prices for oil that were sure to follow its substitution for coal fuel. Since then the industry has experienced a magnificent success, the sales exceeding 20,000,000 barrels a year, while the price is lower than ever.

A curious impression seems to have gained ground to the effect that the Standard Oil Company does not want to sell oil for fuel. It may be stated authoritatively that the company is not only able but willing to sell and deliver oil for fuel purposes in any quantity that may be desired. It is now delivering oil for fuel purposes in fourteen States of the Union. For its sales in Chicago and the West and Northwest, the delivery is by tank cars from the terminus of the pipe line at South Chicago, to which point it is pumped from Lima, O. The Chicago price is 1-2/3c. per gallon, or 70c. per barrel of 42 gallons, f.o.b. cars at Chicago.

A great many of the brick manufacturers here and throughout the Northwest are beginning to use crude petroleum as a substitute for soft coal. It is smokeless, for the fine spray of oil which comes from the injector consists of such minute drops of the liquid and is so thoroughly mixed with oxygen that when it burns the combustion is complete, and only steam and carbonic acid gas go out of the top of the kiln. Not a speck of soot comes from the kiln or the smokestack or soils the whitewashed purity of the boiler room. Oil fuel is absolutely clean. It is labor saving, too. No fireman has to keep shoveling coal, there are no ashes to be dragged out from under the furnace grates, and there are no clinkers to clog up the bars. One man, by turning a valve, may regulate the heat of a kiln containing one million brick.

Not only is it cleaner than coal and calls for less labor, but it is actually cheaper as a fuel. A barrel and a half of crude oil is equal for furnace fuel to a ton of the best Illinois bituminous coal, and at 70c. a barrel any one can easily calculate the advantages petroleum has over its smoky rival. Theoretically, two barrels of oil equal in heating power one ton of best Pittsburg coal.

An examination into the relative cost of the Pittsburg and Chicago coal to the oil consumed shows that the price of oil at Pittsburg is 59c. per barrel of 42 gallons, and slack coal can be purchased at from 70c. to 80c. per ton, and the best quality of lump coal at from $1.10 to $1.25 per ton, while the same quality of fuel can be bought in Chicago at about 70c. a barrel, as against coal at from $2 to $3.50 per ton. It would, therefore, look as though there could be no question whatever as to the economy and advantages to be derived from the use of oil as a fuel in this vicinity.

The weight of oil required is less than half that of average coal to produce the same amount of steam.

A great advantage in using oil as fuel in brick burning is that the fires are always under the absolute and direct control of the man in charge of the burning, who can regulate the volume of flame to the nicest degree and throw the heat to any part of the arches that he may desire.

From present indications, oil will be the fuel adopted generally for generating power and for brick burning in Chicago, as it saves the boilers, avoids grate bars, saves dirt and cinders, and reduces running expenses, etc.

Much skepticism was at first exhibited in Chicago only a few years ago when one of the leading brick manufacturers attempted to burn a kiln of brick with coal for fuel. Nearly all the brickmakers then in business put on wise looks and predicted the failure of the experiment with coal. But coal proved to be a better and cheaper fuel than wood, and in five or six years wood was used only for the kindling of the coal fires.

Then came the attempt to burn brick with crude oil, and the experiment having proved a success, coal has been banished from the leading brick yards in Chicago and vicinity.

The Purington-Kimball Brick Co., Adams J. Weckler, Weber & La Bond, the May-Purington Brick Co., the Union Brick Co., and the Pullman Brick Co., all having headquarters in Chicago, as well as the Peerless Brick Co. and the Pioneer Fireproof Construction Co., both of Ottawa, Ill., are using crude oil fuel for brick burning.

Lima crude oil is used, and it is atomized by means of steam in small furnaces extending about two feet from the face of the brick kilns, and in which furnaces combustion occurs, and the conversion of the oil and steam into a gaseous fuel is secured. There is little doubt that the fuel employed in the future by the successful brick manufacturer must be in the gaseous form. Owing to the enormous cost of handling coal, wood, and other crude fuel, and of removing the ash resulting from such fuel, it has been demonstrated in practice by the use of crude oil that the expense connected with the burning of brick can be reduced fully 60 per cent. This large saving is made by converting crude petroleum into gas and utilizing this fuel, either directly in the arches of the kiln or by converting the crude oil into gas in a gas producer, and drawing this fuel gas from the producer and burning the same as required in kilns of suitable construction.