« PreviousContinue »
DURING the last few months there has been no especially noteworthy or salient event in the domain of the applied science of engineering, but at the same time there has been distinct progress along many lines which have already been discussed in these reviews.
Thus the question of the application of the steam-turbine to Transatlantic express steamers, already mentioned as under serious consideration, has been definitely settled by the favorable report of the scientific commission, after an exhaustive examination of all sides of the subject. The new vessels will involve a number of structural and operative problems of serious magnitude. In order to meet the British Government's requirement of a sea speed of 241⁄2 to 25 knots, it is recommended that a length of 760 feet be given to the hull, while it is estimated that 70,000 horse-power will be necessary for the propulsion. Since it will be impracticable to transmit this great power through two or even three shafts, it has been decided to provide four shafts, with as many propellers. The two outer shafts will be driven by the highpressure turbine, while the inner shafts are operated by low-pressure machines, taking the steam which has already done a portion of its work in the first pair. On the inner shafts will also be placed the reversing turbines, and, as there is rarely occasion for backing at full speed, these will furnish ample power for the purpose.
Although it was expected that a saving of nearly ten per cent in weight might be effected by the use of turbines, the gain in this respect over reciprocating engines is now believed to be much less, probably nearer three per cent. The freedom from vibration, however, is an important element on shipboard, and the combined advantages of space and weight probably influenced the commission in making its decision.
The steam economy of the turbine is about the same as that of a first-class reciprocating engine when operated at full load, and the service on an ocean liner will enable this condition to be realized during the greater portion of the time. It has been shown, however, that the best forms of reciprocating engine possess a greater degree of flexibility,
so to speak, and under the varying conditions of central station work, it is probable that they will enable a higher general economy to be secured for such service.
While the builders of various types of the steam-engine are endeavoring to perfect that important machine, there are many indications that it will ultimately be superseded by the internal-combustion motor using gas, liquid hydrocarbons, or even pulverized coal as fuel. The difficulties connected with the construction of large gas-engines appear to have been surmounted; and the large Cockerill engine of 600 horse-power, which attracted so much attention at Paris in 1900, is now entirely overshadowed by the large machines since constructed. The large engines which have been built hitherto have been designed for use with the waste gases of blast-furnaces, although there is no reason why they should not be adapted for other fuels. For smaller motors, however, it has become evident that other liquid fuels are necessary besides the petroleum products, gasoline, petrol, essence, etc., now employed. Under suitable conditions it has become evident that alcohol is entirely adapted as a fuel for internal-combustion motors of moderate size. It has a lower calorific power than petrol, but the heat of combustion is not necessarily a measure of the value of a fuel. The real effect is that of the mixed charge in the cylinder; and the richer fuel, when diluted with its proper proportion of air, is no more powerful than the one of lower heating value.
Practical experience with alcohol has shown that it is entirely satisfactory in operation. The only impediment to its general use is the heavy tax which is placed upon it as an intoxicating beverage. By treating it so as to render it undrinkable by the addition of gasoline, benzine, or other similar substance - it may be made suitable for relief from taxation; and, this point once provided for, there is no doubt that a variety of processes for producing a cheap and efficient fuel from sawdust, potatoes, sugar wastes, and many other materials would be actively employed.
Another application of liquid fuel, the use of petroleum in the place of coal for generating steam, especially for marine service, is receiving renewed attention. For more than two years, the naval board appointed by the United States Government has been making exhaustive experiments for the purpose of determining the real practicability of using oil in the boiler furnaces. I have already referred to some portion of these
investigations, and it is to be hoped that a mistaken economy will not prevent the publication of the full detailed report of the work of the board. Not only in the United States, but in various parts of Europe, this subject has received much attention. The vessels plying on the Black Sea have long used crude oil from the Baku district for fuel, and numerous successful applications of liquid fuel have been made upon the locomotives on the neighboring railways. Some recent experiments made in Italy upon a vessel of the "Navigazione Generale Italiana,” with oil burners fitted to boilers originally intended for coal, have demonstrated that one pound of Texas oil was equivalent to about one and one-half pounds of coal. The commercial advantage must necessarily depend upon the relative prices of coal and oil at the given locality. An important element in connection with the use of oil fuel on steamships is the facility with which the handling of the furnaces is effected. The manipulation of the oil burners is readily performed by a few men, with little or no labor, while it is generally admitted that the stoking of marine boilers with coal is most exhausting and difficult work. The use of oil fuel, by reducing the number of men required and removing altogether the objectionable character of the work, would go far to solve many of the labor difficulties now generally experienced upon steamships.
During the last ten or fifteen years, the use of special apparatus for the accurate testing of the performance of steam-locomotives has become a matter of scientific and practical interest. Formerly locomotives were adjusted by the builders and put immediately into active service. The valves were adjusted by "sound," as it was termed; the engineer judging of the accuracy of this work by the regularity or otherwise of the puffs of exhaust steam. This crude method was succeeded by the use of the indicator, the dynamometer drawbar, and various auxiliary devices for use in connection with operative road trials. It has been realized, however, that all the elements in locomotive action could be critically investigated only by having the machine stationary. The testing plant constructed at Purdue University in 1890, under the supervision of Prof. Goss, was arranged to have the engine mounted upon suitable supporting wheels, which, being rotated by the action of the drivingwheels of the locomotive, permitted the machinery to be run at full speed. A braking device upon the supporting wheels permitted any resistance to be applied and measured, while the pull of the drawbar upon a fixed traction dynamometer became a ready subject for investigation.
From this original installation, intended principally for the instruction of students, has grown the extensive testing plant installed at the St. Louis Exposition under the auspices of the Pennsylvania Railroad Company. This plant, which is being operated under the direction of an advisory committee composed of expert specialists, members of the American Society of Mechanical Engineers and of the American Railway Master Mechanics' Association, will be used for making elaborate comparative tests upon a number of locomotives, representing the principal types in active service at the present time. There is every reason to believe that a large amount of important information, practical and technical in character, will be obtained.
Record should be made of the progress which has recently been made in so-called "motor boats." For some time small launches have been fitted with internal-combustion motors, but it is only since increased attention has been given to the production of light-weight highpower motors for automobiles that the applicability of such engines for small boats has been demonstrated. The appropriateness of the title "motor boats" may be questioned when it is remembered that the term really includes all boats which are mechanically propelled; but no better name yet appears to have been suggested. As a matter of fact, the conditions are much less difficult for the high-speed internal-combustion motor afloat than when placed upon a road vehicle. The need of protection from dust is absent; there is no difficulty about cooling the cylinders; no arrangement of brakes is necessary; and there is small trouble about accessibility. Accordingly the designing of the highspeed motor boat is distinctly a simpler problem than that of the satisfactory automobile.
Apart from the use of internal-combustion motors for pleasure boats, an important application of such machines is found in connection with the propulsion of submarines. The steam-engine is obviously unsuitable for use with submersible boats; and while electric power, derived from storage-batteries, is undoubtedly available and satisfactory during periods of complete submersion, some other propelling power must be provided for general service and for charging the batteries. The successful boats, both in Europe and in America, employ some such combination for their motive power, and without such machinery their successful operation would be impracticable.
Recent trials of submarine boats have been very successful in
demonstrating the degree of perfection to which these later additions to the machinery of warfare have been brought. The tests of the Holland boat, "Fulton," at Newport, have shown that such a vessel can remain submerged for periods of from twelve to fifteen hours, and that excellent control may be had under such conditions. The ability to destroy hostile vessels has been fully demonstrated, and it is evident that such boats must form an important element in naval warfare. The recent manœuvres in France have also proved the entire feasibility of secret submarine attack upon large vessels - even when it is anticipated and a careful lookout is kept and there is no doubt that henceforward the work of the engineer beneath the water must be considered as well as that above the surface. It has been shown that the position and movements of submarines may be detected by observation from a balloon at some distance above the surface of the water, the dark outline of the hull being visible under such circumstances. It is not often that such a means of observation can be safely employed, however; and in any case it would be applicable by daylight only, while the attacks of submarines will naturally be made by night whenever practicable.
The part of the engineer in the Russian-Japanese conflict will doubtless appear more fully as further accurate accounts of the military and naval operations are furnished. At the present time, however, there is ample evidence to show not only that modern fighting machinery must be designed and constructed by able engineers, but that a corresponding degree of technical ability must be given to the maintenance and operation of the appliances. It was a matter for comment that, in the war between Spain and America, the machinery of the warships and torpedo-boats of the former nation, although of the best design and construction, failed largely to effect its intended purpose. This failure was undoubtedly due to the lack of competent engineering attention and control. In some circles the effectiveness of the torpedo-boat was undervalued because of these failures. In the light of the experience at Port Arthur, this opinion must be held subject to revision, while the opposite view, that of the disparagement of the battleship, may also be permitted to remain in suspense until the final outcome of the struggle. It is also interesting to note that the control of great engineering works, such as the Manchurian railway and the important harbor works at Dalny, plays an essential part in the operations of warfare.
A rather amusing element in the relation of applied science to warfare appears in the attempt to suppress the use of space telegraphy for