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 6½ 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.
A lecture delivered before the students of Sibley College, Cornell University, December 4, 1891.—The Crank.]
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.