Chapter 7

The visitor to the late Naval Exhibition interested in shipping will have remarked at each of the several exhibits of the great firms a model of a projected steamer, intended to reduce the present record of the six days' voyage across the Atlantic--the _ne plus ultra_ at this time of steam navigation. To secure this present result a continuous steaming for the six days at 20 knot speed is requisite, not to mention an extra day or two at each end of the voyage. The City of Paris and the City of New York, Furst Bismarck, Teutonic and Majestic are capable of this, with the Umbria and Etruria close behind at 18 to 19 knots. Only ten years ago the average passage, reckoned in the same way as from land to land--or Queenstown to Sandy Hook--was seven days with a speed of 17 knots, the performance of such vessels as the Arizona and Alaska. Twenty years ago the length of the voyage was estimated as seven and a half to eight days at a speed of 16 knots, the performance of such vessels as the Germanic and Britannic of the White Star fleet of 5,000 tons and 5,000 horse power. Thirty years ago the paddle steamer was not yet driven off the ocean, and we find the Scotia crossing in between eight and nine days, at a speed of 13 or 14 knots. In 1858 ten and a half to twelve and a half days was allowed for the passage between Liverpool and New York. So as we recede we finally arrive at the pioneer vessels, the Sirius and Great Western, crossing in fourteen to eighteen days at a speed of 6 to 8 knots. For these historical details an interesting paper may be consulted, "De Toenemende Grootte der Zee-Stoombooten," 1888, by Professor A. Huet, of the Delft Polytechnic School.

Each of the last two or three decades has thus succeeded, always, however, with increasing difficulty, in knocking off a day from the duration of the voyage. But although the present six-day 20 knot boats are of extreme size and power, and date only from the last two or three years, still the world of travelers declares itself unsatisfied. Already we hear that another day must be struck off, and that five-day steamers have become a necessity of modern requirements, keeping up a continuous ocean speed of 23½ knots to 24 knots. Shipbuilders and engineers are ashamed to mention the word _impossible_; and designers are already at work, as we saw in the Naval Exhibition, but only so far in the model stage; as the absence of any of the well known distinguishing blazons of the foremost lines was sufficient to show that no order had been placed for the construction of a real vessel. It will take a very short time to examine the task of the naval architect required to secure these onerous and magnificent conditions, five days' continuous ocean steaming at a speed of 24 knots.

The most practical, theory-despising among them must for the nonce become a theorist, and argue from the known to the unknown; and, first, the practical man will turn--secretly perhaps, but wisely--to the invaluable experiments and laws laid down so clearly by the late Mr. Froude. Although primarily designed to assist the Admiralty in arguing from the resistance of a model to that of the full size vessel, the practical man need not thereby despise Froude's laws, as he is able to choose his mode: to any scale he likes, and he can take his experiments ready made by practice on a large scale, as Newton took the phenomena of astronomy for the illustration of the mechanical laws. Suppose then he takes the City of Paris as his model, 560 ft. by 63 ft., in round numbers 10,000 tons displacement, and 20,000 horse power, for a speed of 20 knots, with a coal capacity of 2,000 tons, sufficient, with contingencies, for a voyage of six to eight days. Or we may take a later 20 knot vessel, the Furst Bismarck, 500 ft. by 50ft., 8,000 tons, and 16,000 horse power, speed 20 knots, and coal capacity 2,700 tons, to allow for the entire length of voyage to Germany.

In Froude's method of comparison the laws of mechanical similitude are preserved if we make the displacements of the model and of its copy in the ratio of the sixth power of the speeds designed, or the length as the square of the speed. Our new 24 knot vessel, taking the City of Paris as a model, would therefore have 10,000 (24 ÷ 20)^{6} = 29,860, say 30,000 tons displacement, and would be 800 ft. × 90 ft. in dimensions. The horse power would have to be as the _seventh_ power of the speed, and our vessel would therefore have 20,000 (24 ÷ 20)^{7}, or say 72,000 horse power. Further applications of Froude's laws of similitude will show that the steam pressure and piston speed would have to be raised 20 per cent., while the revolutions were discounted 20 per cent., supposing the engines and propellers to be increased in size to scale. To provide the requisite enormous boiler power, all geometrical scale would disappear; but it would carry us too far at present to follow up this interesting comparison.

Our naval architect is not likely at present to proceed further with this monstrous design, exceeding even the Great Eastern in size, if only because no dock is in existence capable of receiving such a ship. He has however learned something of value, namely, that this vessel, if the proper similitude is carried out, is capable of keeping up a speed of 24 knots for five days with ample coal supply, provided the boilers are not found to occupy all the available space. For it is an immediate consequence of Froude's laws that in similar vessels run at corresponding speeds over the same voyage, the coal capacity is proportionately the same, or that a ton of coal will carry the same number of tons of displacement over the same distance. Thus our enlarged City of Paris would require to carry about 4,000 tons of coal, burning 800 tons a day.

With the Britannic and Germanic as models of 5,000 tons and 5,000 horse power at 16 knot speed, the 24 knot vessel would require to be of 57,000 tons and 85,000 horse power, to carry sufficient coal for the voyage of 3,000 miles. These enormous vessels being out of the question, the designer must reduce the size. But now the City of Paris will no longer serve as a model, he must look elsewhere for a vessel of high speed, and smaller scale, and naturally he picks out a torpedo boat at the other end of the scale. A speed of 24 knots--and it is claimed even of 25, 26, and 27 knots--has been attained on the mile by a torpedo boat. But such a performance is useless for our mode of comparison, as sufficient fuel at this high speed for ten or twelve hours only at most can be carried--a voyage of, say, 500 miles; while our steamer is required to carry coal for 3,000 miles. The Russian torpedo boat Wiborg, for instance, is designed to carry coal for 1,200 miles at 10 knot speed; but at 20 knots this fuel would last only twenty-seven hours, carrying the vessel 540 miles. It will now be found that with this limited coal capacity the speed of the ordinary torpedo boat must be reduced considerably below 10 knots for it to be able to cross the Atlantic, 3,000 miles under steam. So that, even at a possible speed of 10 knots for the voyage, the full sized 24 knot five-day vessel, of which the best torpedo boat is the model, must have (2.4)^{6}, say 200 times the tonnage, and (2.4)^{7}, or 460 times the horse power. The enlarged Wiborg would thus not differ much from the enlarged City of Paris. A better model to select would be one of the recent dispatch boats, commerce destroyers, or torpedo catchers, recently designed by Mr. W.H. White, for our navy--the Intrepid or Endymion, for instance. The Intrepid is 300 ft. by 44 ft., 3,600 tons, and 9,000 horse power for 20 knot speed, with 800 hours' coal capacity for 8,000 miles at 10 knot speed; which will reduce to 3,000 miles at 16 knots, and 2,000 miles at 20 knots.

The Endymion is 360 ft. by 60 ft., with coal capacity for 2,800 miles at 18 knot speed, or for about 144 hours or six days. The enlarged Endymion for the same voyage of 2,800 miles in five days, or at 21½ knot speed, would be 44 per cent larger and broader, that is 520 ft. by 86 ft., and of threefold tonnage, and three and a half times, or about 30,000 horse power--about the dimensions of the Furst Bismarck, but much more powerfully engined. This agrees fairly with the estimate in the SCIENTIFIC AMERICAN of 19th Sept, 1891., where it is stated that twenty-two boilers, at a working pressure of 180 lb. on the square inch, would be required, allowing 1½ lb. of coal per horse power hour.

The Intrepid, enlarged to a 24 knot boat, for the same length of voyage of 3,000 miles, would be 650 ft. by 100 ft., 40,000 tons, and about 45,000 horse power. So now we are nearing the Messrs. Thomson design in the Naval Exhibition of the five-day steamer, 23½ knot speed, 630 ft. by 73 ft., and 30,000 to 40,000 horse power.

No one doubts the ability of our shipbuilding yards to turn out these monsters; and on the measured mile, and for a good long distance, we shall certainly see the contract speeds attained and some excelled. But the whole difficulty turns on the question of the coal capacity, and whether it is sufficient to last for even five days or for 3,000 miles. Every effort then must be made to shorten the length of the voyage from port to port; and we may yet see Galway and Halifax, only 2,200 miles apart, once more mentioned as the starting points of the voyage as of old, in the earliest days of steam navigation. In those days the question of fuel supply was a difficulty, even at the then slow speeds, in consequence of the wasteful character of the engines, burning from 7 lb. of coal and upward per horse power hour. Dr. Lardner's calculations, based upon the average performance of those days, justified him in saying that steam navigation could not pay--as was really the case until the introduction of the compound engine.

It is recorded in Admiral Preble's "Origin and Development of Steam Navigation," Philadelphia, 1883, page 160, that the Sirius, 700 tons and 320 horse power, on her return voyage had to burn up all that old be spared on board, and took seventeen days to reach Falmouth. An interesting old book to consult now is Atherton's "Tables of Steamship Capacity," 1854, based as they are upon the performance of the marine engine of the day. Atherton calculates that a 10,000 ton vessel could at 20 knots carry only 204 tons of cargo 1,676 miles, while a 5,000 ton vessel at 18 knots on a voyage of 3,000 miles could carry no cargo at all. Also that the cost per ton of cargo at 16 knots would be twenty times the cost at eight knots, implying a coal consumption reaching to 12 lb. per horse power hour. It is quite possible that some invention is still latent which will enable us to go considerably below the present average consumption of 2 lb. to 1½ lb. per horse power hour; but at present our rate of progress appears asymptotic to a definite limit.

To conclude, the whole difficulty is one of fuel supply, and it is useless to employ a fast torpedo boat as our model, except at the speed at which the torpedo boat can carry her own fuel to cross the Atlantic. If the voyage must be reduced in time, let it be reduced from six days to four, by running between Galway and Halifax, a problem not too extravagant in its demands for modern engineering capabilities. A statement has recently gained a certain amount of circulation to the effect that the Inman Company was about to use petroleum as fuel, in order to obtain more steam. We have the best possible authority for saying there is not the least syllable of truth in this rumor. It has also been stated that since solid piston valves have been fitted to the Teutonic in lieu of the original spring ring valves, she has steamed faster. This rumor is only partially true. Her record, outward passage, of 5 days 16 hours 31 minutes, was made on her previous voyage. She has, however, since made her three fastest trips homeward.--_The Engineer_.

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THE MILITARY ENGINEER AND HIS WORK.[1]

By Col. W.R. KING.

[Footnote 1: A lecture delivered before the students of Sibley College, Cornell University, December 4, 1891.--_The Crank_.]

It is not an easy matter to present a dry subject in such an attractive form as to excite a thrilling interest in it, and military science is no exception to this rule. An ingenious military instructor at one of our universities has succeeded in pointing out certain analogies between grand tactics and the festive game of football, which appears to have greatly improved the football, if we may judge from the recent victories of the blue over the red and the black and orange, but it is not so clear that the effect of the union has been very beneficial to military science; and even if such had been the case, I fear there are no similar analogies that would be useful in enlivening the subject of military engineering.

From the earliest times of which we have record man has been disposed to strive with his fellow man, either to maintain his own rights or to possess himself of some rights or material advantage enjoyed by others. When one or only a few men encroach on the rights of others in an organized community, they may be restrained by the legal machinery of the state, such as courts, police, and prisons, but when a whole community or state rises against another, the civil law becomes powerless and a state of war ensues. It is not proposed here to discuss the ethics of this question, nor the desirability of providing a suitable court of nations for settling all international difficulties without war. The great advantage of such a system of avoiding war is admitted by all intelligent people. We notice here a singular inconsistency in the principles upon which this strife is carried on, viz.: If it be a single combat, either a friendly contest or a deadly one, the parties are expected to contest on equal terms as nearly as may be arranged; but if large numbers are engaged, or in other words, when the contest becomes war, the rule is reversed and each party is expected to take every possible advantage of his adversary, even to the extent of stratagem or deception. In fact, it has passed into a proverb that "all things are fair in love and war."

Now one of the first things resorted to, in order to gain an advantage over the enemy, was to bring in material appliances, such as walls, ditches, catapults, scaling ladders, battering rams, and subsequently the more modern appliances, such as guns, forts, and torpedoes, all of which are known as engines of war, and the men who built and operated these engines were very naturally called engineers. It is this kind of an artificer that Shakespeare refers to when he playfully suggests that "'tis the sport to have the engineer hoist with his own petard."

The early military engineer has left ample records and monuments of his genius. The walls of ancient cities, castles that still crown many hills in both hemispheres, the great Chinese wall, the historical bridge of Julius Cæsar, which with charming simplicity he tells us was built because it did not comport with his dignity to cross the stream in boats, the bridge of boats across the Hellespont, by Xerxes, are all examples of early military engineering. The Bible tells us "King Uzziah built towers at the gates of Jerusalem, and at the turning of the wall, and fortified them." We may note in passing that the buttresses, battlements, and bartizans with which our modern architects ornament or disfigure churches, peaceful dwellings, and public buildings, are copied from the early works of the military engineer.

Coming down to the military engineers of our own country, we find that one of the first acts of the Continental Congress, after appointing Washington as commander-in-chief, was to authorize him to employ a number of engineers. It was not, however, until 1777 that a number of engineer officers from the French army arrived in this country, and were appointed in the Continental army. General DuPortail was made Chief Engineer, and Colonel Kosciusko, the great Polish patriot, was among his assistants. Other officers of the Continental army were employed on engineering duty; and under their supervision such works as the forts and the great chain barrier at West Point were built, and the siege operations around Boston and Yorktown were carried on.

After the close of the war, in 1794, a Corps of "Artillerists and Engineers" was organized. This corps was stationed at West Point, and became the nucleus of the United States Military Academy. In 1802, by operation of the law reorganizing the army, this corps was divided, as the names would indicate, into an Artillery Corps and Corps of Engineers. The Corps of Engineers consisted of one major, two captains, four lieutenants, and ten cadets. The Artillery Corps was again divided into the Ordnance Corps and several regiments of artillery, now five in number, while the duties of the Corps of Engineers were divided between the Engineer Corps and a Corps of Topographical Engineers, organized at a later date; but on the breaking out of the late rebellion it was deemed best to unite the two corps, and they have so remained until the present time. The Corps of Engineers now consists of 118 officers of various grades, from second lieutenant to brigadier general, of which last grade there is only one officer, the chief of the corps, and it requires something more than an average official lifetime for the aforesaid lieutenant to attain that rank. Hardly one in ten of them ever reach it. Daniel Webster's remark to the young lawyer, that "there is always room at the top," will not apply to the Corps of Engineers. The officers are all graduates of the Military Academy, which institution continued as a part of the Corps of Engineers until 1866. The vacancies in the corps are filled by the assignment to it of from two to six graduates each year, and there is attached to the corps a battalion of four companies of enlisted men, formerly called Sappers and Miners, but now known as the Battalion of Engineers.

We now come naturally to the duties of our military engineer, and here I may remark that these duties are so varied and so numerous that a detailed recital of them would suggest Goldsmith's "Deserted Village:"

... "And still the wonder grew That one small head could carry all he _ought to know_"

[Never lose sight of fact for the sake of rhyme.]

In general terms, his duties consist of:

1. Military surveys and explorations.

2. Boundary surveys.

3. Geodetic and hydrographic survey of the great lakes.

4. Building fortifications--both permanent works and temporary or field works.

5. Constructing military roads.

6. Pontoniering or building military bridges, both with the regular bridge trains and with improved materials.

7. The planning and directing of siege operations, either offensive or defensive; sapping, mining, etc.

8. Providing, testing and planting torpedoes for harbor defense when operating from shore stations.

9. Staff duty with general officers.

10. Improving rivers and harbors.

11. The building and repairing of lighthouses.

12. Various special duties as commissioner of District of Columbia, superintendent military academy, commandant engineer school, instructors at both of these schools, attaches to several foreign legations, for the collection of military information, etc.

It would, of course, exceed the proper limits of a single lecture to go into the details of these many duties, but we may take only a passing glance at most of them, and give more special attention to a few that may involve some points of interest. Perhaps the most interesting branch of the subject would be that of permanent fortifications, or what amounts to almost the same thing in this country, sea coast defenses. And here our trouble begins, for, while civil engineers have constant experience to guide them, their roads, bridges, and other structures being in constant use, the military engineer has only now and then, at long intervals, a war or a siege of sufficient extent to furnish data upon which he can safely plan or build his structures. Imagine a civil engineer designing a bridge, road, or a dam to meet some possible future demand, without having seen such a structure used for twenty years or more, and you can form some estimate of the delightful uncertainties that surround the military engineer when called upon to design a modern fort. The proving ground shows him that radical improvements are necessary, but actual service conditions are almost entirely wanting, and such as we have contradict many of the proving ground theories. Thus we have the records of shot going through 25 inches of iron or 25 feet of concrete on the proving ground; but such actual service tests as the bombardment of Fort Sumter, Fort Fisher, and the forts at Alexandria contradict this entirely, and indicate that, except for the moral effect, our old forts, with modern guns in them and some additional strengthening at their weaker points, would answer all purposes so far as bombardment from fleets is concerned. This is not saying that the forts are good enough in their present condition, but simply that they can readily be made far superior in strength, both offensive and defensive, to any fleet that could possibly be provided at anything like the same expense, or in fact at any expense that would be justified by the condition of our treasury, either past, present, or probable future. It might be added that a still more serious difficulty in the way of the military engineer, so far as practice and its consequent experiences are concerned, is that for many years past, until quite recently, there have been no funds either for experiments or actual work on fortifications, so that very little has been done on them during the last twenty years.

Without going into the question of the necessity for sea coast defenses, we may assume that an enemy is likely to come into one of our harbors and that it is desirable to keep him out. What provisions must be made to accomplish this, i.e., to secure the safety of the harbors and the millions of dollars' worth of destructible property concentrated at the great trade centers that are usually located upon those harbors? We must first take a look at the enemy and see what he is like before we can decide what will be needed to repel his attack. For this purpose we need not draw on the imagination, but we may simply examine some of the more recent armadas sent to bombard seaports. For example, the fleet sent by Great Britain to bombard the Egyptian city of Alexandria, in 1882. This fleet consisted of eight heavy ironclad ships of from 5,000 to 11,000 tons displacement and five or six smaller vessels; and the armament of this squadron numbered more than one hundred guns of all calibers, from the sixteen inch rifle down to the seven inch rifle, besides several smaller guns. But this fleet represented only a small fraction of England's naval power. During some recent evolutions she turned out thirty-six heavy ironclads and forty smaller vessels and torpedo boats. The crews of these vessels numbered nearly 19,000 officers and men, or about three times the entire number in our navy. Such a fleet, or, more likely, a much larger one, might appear at the entrance say of New York harbor within ten days after a declaration of war, and demand whatever the nation to which it belonged might choose, with the alternative of bombardment.