 |
Using the above formula we can make out a table as follows:
-+ -+ -+ -+ -+ + -+ Plate. Backi'g Gun, service w, a, V. Energy, Inches. Inches. shot. Pounds. Inches. f. 8. Impact. f. tons. -+ -+ -+ -+ -+ + -+ 6 36 6" B.L.R. 100 5.96 1389 1337 7 36 6" " 100 5.96 1528 1619 8 36 8" " 250 7.96 1213 2550 9 36 8" " 250 7.96 1308 2966 10 36 8" " 250 7.96 1399 3390 11 36 8" " 250 7.96 1489 3839 12 36 10" " 500 9.96 1247 5386 13 36 10" " 500 9.96 1315 5987 14 36 10" " 500 9.96 1381 6608 15 36 12" " 850 11.96 1215 8699 16 36 12" " 850 11.96 1269 9710 17 36 12" " 850 11.96 1332 10454 18 36 12" " 850 11.96 1374 11124 19 36 12" " 850 11.96 1425 11965 20 36 12" " 850 11.96 1476 12837 -+ -+ -+ -+ -+ + -+
No projectile or fragment of the plate or projectile must get wholly through the plate and backing. The plate must not break up or give such cracks as to expose the backing, previous to the third shot.
The penetration of projectiles of different forms into various styles of armor has been very thoroughly studied and many attempts have been made to bring the subject down to mathematical formulae. These formulae are based on several suppositions, and agree very closely with results obtained in actual experiments, but there are so many varying conditions that it is extremely doubtful if any formulae will ever be written that will properly express the penetration.
Many different forms have been given to the heads of projectiles, as flat, ogival, hemispherical, conoidal, parabolic, blunt trifaced, etc.
The flat headed projectile has the shape of a right cylinder, and acts like a punch, driving the material of the armor plate in front of it. These projectiles are especially valuable when firing at oblique armor, for they will bite or cut into the armor when striking at an angle of thirty degrees.
The ogival head acts more as a wedge, pushing the metal aside, and generally will give more penetration in thick solid plates than the flat headed projectile. The ogival head is usually designed by using a radius of two calibers.
The hemispherical, conoidal, parabolic and blunt trifaced all give more or less of the wedging effect. The blunt trifaced has all the good qualities of the ogival of two calibers. It bites at a slightly less angle, and the three faces start cracks radiating from the point of impact.
Forged steel is the best material for armor-piercing projectiles, but many are made of chilled cast iron, on account of its great hardness and cheapness.
The best weight for a projectile is found by the formula
w = d cubed (0.45 to 0.5)
w being the weight in pounds, d the diameter in inches and 0.45 to 0.5 having been determined by experiment.
With a light projectile we get a flat trajectory, and accuracy at short ranges is increased. With a heavy projectile the resistance of the air has less effect and the projectile is advantageously employed at long ranges.
In the following formulae, used in calculating the penetration of projectiles in rolled iron armor,
g = the force of gravity. w = the weight of projectile in pounds. d = the diameter of projectile in inches. v = the striking velocity in feet per second. P = the penetration in inches.
Major Noble, R.A., gives
1.6 / w v squared P = / / ———————— / [pi] g d 11334.4
[TEX: P = sqrt[1.6]{frac{w v^2}{pi g d 11334.4}}]
U.S. Naval Ordnance Proving Ground uses
___ 2.035/ w v squared P = / / ———————- / [pi] g d 3852.8
[TEX: P = sqrt[2.035]{frac{w v^2}{pi g d 3852.8}}]
Col. Maitland gives
w v squared P = —————— g d squared 16654.4
[TEX: P = frac{w v^2}{g d^2 16654.4}]
Maitland's latest formula, now used in England, is
_ v /w P = ——- / - - 0.14 d 608.3 d
[TEX: P = frac{v}{608.3} sqrt{frac{w}{d}} - 0.14 d]
General Froloff, Russian army, gives
w v P = ——— d squared 576
[TEX: P = frac{w v}{d^2 576}]
for plates less than two and one-half inches thick, and
w v P = ——— - 1.5 d squared 400
[TEX: P = frac{w v}{d^2 400} - 1.5]
for plates more than two and one-half inches thick.
If [theta] be the angle between the path of the projectile and the face of the plate, then v in the above formulae becomes v sin [theta].
When we come to back the plates, their power to resist penetration becomes greater, and our formula changes. The Gavre formula, given above, is used to determine the velocity necessary for a projectile to pass entirely through an iron plate and its wood backing.
Compound and steel armor are said to give about 29 per cent. more resisting power than wrought iron, but in one experiment at the proving ground, at Annapolis, a compound plate gave over 50 per cent. more resisting power than wrought iron.
The Italian government, after most expensive and elaborate comparative tests, has decided in favor of the Creusot or Schneider all-steel plates, and has established a plant for their manufacture at Terni, near Rome.
The French use both steel and compound plates; the Russians, compound; the Germans, compound; the Swedes and Danes use both. Spain has adopted and accepted the Creusot plate for its new formidable armored vessel, the Pelayo; and China too has recently become a purchaser of Creusot plates.
Certain general rules may be laid down for attacking armor. If the armor is iron, it is useless to attack with projectiles having less than 1,000 feet striking velocity for each caliber in thickness of plate. It is unadvisable to fire steel or chilled iron filled shells at thick armor, unless a normal hit can be made. When perforation is to be attempted, steel-forged armor-piercing shells, unfilled, should be used. They may be filled if the guns are of great power as compared to the armor. Steel and compound armor are not likely to be pierced by a single blow, but continued hammering may break up the plate, and that with comparatively low-powered guns.
Wrought iron must be perforated, and hard armor, compound or steel, must be broken up. Against wrought iron plates the projectile may be made of chilled cast iron, but hard armor exacts for its penetration or destruction the use of steel, forged and tempered. Against unarmored ships, and against unarmored portions of ironclads, the value of rapid-firing guns, especially those of large caliber, can hardly be overestimated.
The relative value of steel and compound armor is much debated, and at present the rivalry is great, but the weight of evidence and opinion seems to favor the all-steel plate. The hard face of a compound plate is supposed to break up the projectile, that is, make the projectile expend its energy on itself rather than upon the plate, and the backing of wrought iron is, by its greater ductility, to prevent the destruction of the plate. It seems probable that these two systems will approach each other as the development goes on. An alloy of nickel and steel is now attracting attention and bids fair to give very good results.
The problem to be solved, as far as naval armor is concerned, is to get the greatest amount of protection with the least possible weight and volume, and this reduction of weight and volume must be accomplished, in the main, by reducing the thickness of the plates by increasing the resisting power of the material. In the compound plate great surface hardness is readily and safely attained, but it has not yet been definitely determined what the proper proportionate thickness of iron and steel is.
A considerable thickness of steel is necessary to aid, by its stiffness, in preventing the very ductile iron from giving back to such an extent as to distort the steel face and thus tear or separate the parts of the plate. The ductile iron gives a very low resisting power, its duty being to hold the steel face up to its work. If now we substitute a soft steel plate in the place of the ductile iron, we will get greater resisting power, but our compound plate then becomes virtually an all-steel one, only differing in process of manufacture. The greatest faults of the compound plate are the imperfect welding of the parts and the lack of solidity of the iron. When fired at, the surface has a tendency to chip.
In the all-steel plate we have the greatest resisting power throughout, but there are manufacturing difficulties, and surface hardness equal to that of the compound plate has not been obtained. The manufacturing difficulties are being gradually overcome, and artillerists are in high hopes that the requisite surface hardness will soon be obtained.
The following may be stated as well proved:
1. That steel armor promises to replace both iron and compound.
2. That projectiles designed for the piercing of hard armor must be made of steel.
3. That the larger the plate, the better it is able to absorb the energy of impact without injury to itself.
4. That the backing must be as rigid as possible.
* * * * *
[FROM ENGINEERING.]
THE COMPRESSED AIR SYSTEM OF PARIS.
The demand for compressed air as a motive power is constantly increasing in Paris; the company, according to its official reports, is financially prosperous, and it seems difficult to understand how it should continue as an actively going concern, unless it at all events paid its way. The central station of St. Fargeau, originally started on modest lines, for maintaining a uniform time by pneumatic pressure throughout Paris, has grown rapidly to very large proportions, though it has never been able to supply the demand made on it for power; and at the present time a second and still larger station is being constructed in another part of Paris. We confess that we do not understand why such large sums of money should continue to be spent if the enterprise is not commercially a sound one, nor how men of such eminence in the scientific world as Professor Riedler should, without hesitation, risk their reputation on the correctness of the system, if it were the idle dream of an enthusiast, as many persons—chiefly those interested in electric transmission—have declared it to be.
In describing the developments that have taken place during the last two years, we shall confine ourselves entirely to the details of a report recently made on the subject by Professor Riedler. As soon as it became evident that a very largely increased installation was necessary, it was determined that the new central station should be as free as possible from the defects of the first one. These defects, which were the natural results of the somewhat hasty development of an experimental system, were of several kinds. In the first place, so large a growth had not been contemplated, and the extensions were made more or less piecemeal, instead of being on a regular plan; the location of the central station itself was very unfavorable, both as regards the facilities for obtaining coal and other supplies; the cost of water was excessive, and the amount available, inadequate.
This evil was partly remedied by elaborate arrangements for cooling the injection water so that it could be repeatedly used, a device costly and ineffective, and resulting in extravagant working, to say nothing of the high charges made by the Paris company for supplying water. To these drawbacks had to be added others of an even more serious character. The engines first laid down were not economical, and the compressors employed gave but a very inferior result; with each extension of the plant, the efficiency of both engines and compressors was increased, the most satisfactory, we believe, having been those supplied by the Societe Cockerill, and one of which was exhibited at the Paris exhibition in 1889. Still it was clearly recognized that much better results were possible, results which Professor Riedler claims have been attained and which will be embodied in the new installation now in progress.
This central station is located on the left bank of the Seine, close to the fortifications, opposite Vincennes and not far from the terminal stations of the Orleans and the Paris, Lyons, and Mediterranean Railways; the plan, Fig. 1, shows the position. The works are separated from the river by the quay, over which a bridge will be constructed for the transfer of coal from the landing stages belonging to the company, into the works; as will be readily seen from the plan, it would be quite easy to run junction lines to the two adjacent railways, but with all the advantages given by water carriage, it was considered unnecessary to incur the expense. The river also affords a constant and unlimited water supply, so that none of the difficulties existing at St. Fargeau Station in imperfect condensation and cooling will be met with.
The new installation, called the Central Station of the Quai de la Gare, is laid out on a very large scale, the total generating energy provided for being no less than 24,000 horse power; of this it is intended that 8,000 horse power will be in operation this year, and an extension of 10,000 horsepower in 1892; the power now in course of completion comprises four engines of 2,000 horse power each. Four batteries of boilers will provide steam for these engines. Figs. 2, 3, and 4 show the first section of the installation now in progress; the four groups of engines (three-cylinder condensing) are shown at 1, 2, 3, and 4; the four groups of boilers ranged behind them at F, F; the feed water heaters belonging to each group at V V.
The end of the building abuts against the Seine, and the position of the water conduits for inlet and discharge are indicated at C and A respectively. The installation, when completed, will include very extensive arrangements for transporting and storing coal, and the interior of the boiler houses will be furnished with an overhead system of rails and carriers for handling the coal automatically, as far as possible. All the principal mains and steam pipes are made in duplicate, not only for greater security, but in order that each set of engines and boilers may be connected interchangeably without delay. The Seine supplies an ample quantity of water, but not in a condition either for feeding the boilers, for condensation, or for the air compressors.
Special provisions have therefore to be made to filter the water efficiently before it is used. For this purpose the water is led to a group of four filters (see L, Fig. 4); from them it passes into the tanks, JJ, and is pumped into the heaters. The filters can be rapidly and automatically cleaned by reversing the flow of water through them. Figs. 5 and 6 show the general form of the type of engine adopted, as well as the engine house, some of the mains, etc. They are vertical triple-expansion engines, and are being constructed by MM. Schneider et Cie, of Creusot, with a guarantee of coal consumption not to exceed 1.54 lb. per horse power per hour, with a penalty of 2,000 francs for every 100 grammes in excess of this limit. It is evident that with this restricted fuel consumption, a large margin for economy will exist at the new works, as compared with the St. Fargeau station, where the best engines cannot show anything like this result, while some of the earlier ones are distinctly extravagant, and the whole installation is handicapped with imperfect means of condensation.
Moreover, according to Professor Riedler, the consumption of steam by the new Schneider engines will be only 5.3 kilos. per horse power and per hour as compared with some of the large engines requiring 9 kilos., and the Cockerill engines—using 8 kilos. per hour, not to speak of the older motors that are very extravagant in the use of steam. The St. Fargeau station is worked under a further disadvantage. The constantly increasing demand from subscribers taxes the resources of the station to their fullest extent, so that practically there is no reserve power.
In the new installation the work will be equally constant, but care will be taken always to have a sufficient reserve. Electric lighting will form a considerable part of the duty to be done from this station, and in all cases it is intended to work with accumulators, so that the resistance to be overcome by the engines, so far as this part of the duty is concerned, will be well known and uniform. The engineers of the Compressed Air Co., of Paris, have during the last five years acquired an experience which could only be attained at a high price and at the expense of a certain amount of failure; this period, it is claimed, is now passed, and in the new installation it is possible to put into practice all the valuable lessons learned at St. Fargeau, to say nothing of the more favorable natural conditions under which the extension is being started and the improvements in the compression of the air made by Mr. Popp and Professor Riedler, and to which we shall refer later.
Chiefly in consequence of the high value of the ground, vertical engines were adopted at the new station; the proximity to the river made the foundations somewhat costly, and the risk of occasional floods rendered it desirable to set the level of the engine bedplates 20 inches above the floor of the building; the foundations of the engines are continuous, but are quite independent of the building. There are three compressing cylinders in each set of engines, one being above each steam cylinder. Two of these are employed to compress the air to about 30 lb. per square inch, after which it passes into a receiver and is cooled; it is then admitted into the third or final compressing cylinder and raised to the working pressure at which it flows into the mains. In the illustrations, h, m, and b are the high, intermediate, and low pressure cylinders of one set of engines; as will be seen, each cylinder is on a separate frame connected by girders; directly above the cylinders are the two low and the one high pressure air cylinders, b, m, and h respectively. The former deliver the air compressed to the first stage into the receiver, T (see Fig. 5), whence it passes into the third compression cylinder, and thence by a main into the cylinders, R R, which are in direct communication with the delivery mains; these mains terminate in the subway, T. The water for condensation is brought into the engine house by the channel, C, and the condenser pumps, a, draw direct from this supply; the discharge main back to the river is shown at A. The relative positions of the engine and boiler houses are indicated in Figs. 2 to 5, where F shows the end of one group of boilers; the air supply for the compressors is led from the central raised portion, S, of the roof.
Professor Riedler's first experiments in improving the efficiency of air compressors were made with one of the Cockerill compressors in use at the St. Fargeau Station, and considerable difficulty attended this work, because the machinery was necessarily kept almost in constant operation. These compressors were designed by MM. Dubois and Francois, of Seraing. Two of their leading features were the delivery of the compressed air at as low a temperature as possible, and with a relatively high piston speed of about 400 ft. a minute. The former object is attained by the injection of a very fine water spray at each end of the air cylinder, and its rapid removal with each stroke; the free as well as the compressed air flows through the same passages, one at each end of the cylinder; the inlet valves being placed at the side of these passages, and the outlet or compressed air valves at the top, the compressed air, entering a chamber above the cylinder, common to both valves, and passing thence to the reservoir. The compressed air valves, which are seven in. in diameter, are brought back sharply to their seats at each stroke, by a small piston operated by compressed air flowing through a by-pass from the chamber. The illustrations published by us on page 686 of our forty-seventh volume show the construction of these compressors. The engravings on page 683 of the same volume illustrate the compressors used in a somewhat older part of the installation; they were made by M. Blanchod, of Vevey, and a passing reference may be made to them. The air is admitted through valves in the cylinder, and is forced out through spring-loaded valves; water is admitted into the cylinder to cool the air.
Fig. 7 indicates the modification made by Professor Riedler in one of the Cockerill compressors: a receiver, A, was placed under the two compressing cylinders, B and C. The first stage is completed in the large cylinder, B, the air being compressed to about 30 lb. per square inch; from this it is discharged into the receiver, A, through the pipe, B, where it meets with a spray injection that cools it to the temperature of the water. The final stage is then effected in the smaller cylinder, C, which, drawing the air from the receiver through the pipe, C, compresses it to about 90 lb. and delivers it through the pipe, d, to the mains. We hope shortly to publish drawings of this compressor in its final form; in its elementary stage Professor Riedler claims to have obtained some very remarkable results. He says that the waste spaces in his modification were much smaller than in the Cockerill compressor, while the efficiency of the apparatus was largely increased. The actual engine duty per horse power and per hour was raised, as a maximum, to 384 cubic feet of air at atmospheric pressure, and compressed to 90 lb. per square inch, a marked increase on the duty of the compressors in use at the St. Fargeau station. The Cockerill compressors experimented on at the same time showed a maximum duty of 306 cubic feet of air. A considerable advantage is claimed in drawing clean and cool air from the outside of the building, and beyond the main feature of carrying out the compression in two stages, Mr. Riedler appears to have shown great skill in introducing several minor alterations and improvements in the plant.
Figs. 8, 9 and 10 are diagrams showing the comparative efficiency of the three types of compressors at St. Fargeau—Fig. 10 being a diagram of the Riedler compressor—and indicate the gain derived from the intermediate cooling. The loss is shown to be only 12 per cent., as compared with a loss of 43 per cent. in a large part of the plant, and of 105 per cent. in the earlier compressors of the St. Gothard type. The table given herewith contains a summary of trials made by Professor Gutermuth, and are intended to show the comparative results of an extended trial with three kinds of compressors at St. Fargeau.
PERFORMANCES OF COMPRESSORS AT THE ST. FARGEAU CENTRAL STATION.
- - - R p E e o e Horse- f Amount Quantity Cubic Compressors. v f r Power f of Air of Air Feet of Final Air o Absorbed i Passing Passing Air per Pressure. l E m by c through through Horse- u n i Compres- i Inlet Valves Power t g n sors. e Valves per and per i i u n each Hour. Hour. o n t c Revolu- n e e y tion. s . . - - - cubic cubic lb. per 1. feet feet sq. in. Sturgeon Compressor 37 302 .87 41.67 91,507 261.3 90 Diameter of 37 258 .87 38.13 84,650 276.1 90 cylinder, 23.62 in. and 21.66 in.; stroke, 48.63 in. 2. Cockerill 40 337 .83 46.61 111,864 281.83 90 Compressor. 45 353 .83 46.61 125,844 302.66 90 Diameter of 40 342 .88 49.43 118,632 296.65 90 cylinder, 46 377 .85 48.02 132,534 298.77 90 25.98 in.; 38.67 324 .89 50.14 116,434 306.19 90 stroke, 38.5 337 .89 50.14 115,818 294.18 90 47.24 in. 38.6 329 .91 50.84 117,740 305.13 90 3. Riedler 52 615 .985 77.34 241,300 353.50 90 Compressor. 60 709 .985 76.98 277,128 353.50 90 Diameter of 38 422 .985 77.34 176,330 376.12 90 low-pressure 39 424 .985 77.34 181,030 384.60 90 cylinder, 42.91 in.; diameter of high-pressure cylinder, 26.38 in.; stroke, 47.24 in. - - -
The results thus obtained were so satisfactory that the designs were prepared for the great compressors to be operated at the new central station on the Quai de la Gare by the 2,000 horse power engines.
The transmission of the compressed air through the mains is unavoidably attended with a certain percentage of loss, which, of course, increases with the length of the transmission, the presence of leakage at the joints, etc. Professor Riedler has devoted considerable time to the investigation of this source of waste, and we shall presently refer to the results he has recorded; in the first place, however, we propose to consider what he has to say on the subject of utilizing the air at the points of delivery, and the means employed for obtaining a relatively high efficiency of the motor.
In the earliest stages of the Popp system in Paris it was recognized that no good results could be obtained if the air were allowed to expand direct into the motor; not only did the formation of ice due to the expansion of the air rapidly accumulate and choke the exhaust, but the percentage of useful work obtained, compared with that put into the air at the central station, was so small as to render commercial results hopeless. The practice of heating the air before admitting it to the motor is quite old, but until a few years ago it never seems to have been properly carried out; in several mining installations where this motive power had been long used, more or less imperfect attempts had been made to heat the air; in one instance only, recorded by Professor Riedler, was an efficient means employed. In this case a spray of boiling water was injected into the cylinder and mixed with the air at each stroke, with the result that a very marked economy was obtained.
After a number of experiments, Mr. Popp arrived at the conclusion that the simplest mode of heating, if not the most efficient, was at all events the most suitable, as it was a matter of the first importance that subscribers should not be troubled with the charge of any apparatus involving complication or careful management; he therefore adopted a simple form of cast iron stove lined with fireclay, heated either by a gas jet or by a small coke fire. It was found that this apparatus, crude as it was, answered the desired purpose, until some better arrangement was perfected, and the type was accordingly adopted throughout the whole system. It was quite recognized that this method still left much to be desired, and the economy resulting from the use of an improved form was very marked.
From a large number of trials very carefully carried out by Professor Gutermuth, it was found that more than 70 per cent. of the total number of calories in the fuel employed was absorbed by the air and transformed into useful work. Whether gas or coal be employed as the fuel, the amount required is so small as to be scarcely worth consideration; according to the experiments carried out, it does not exceed 0.09 kilo. per horse power and per hour, but it is scarcely to be expected that in regular practice this quantity is not largely exceeded. Professor Weyrauch has also carefully investigated this part of the subject and fully confirms, if he, indeed, does not go beyond Professor Gutermuth. He claims that the efficiency of fuel consumed in this way is six times greater than when burnt under a boiler to generate steam. He goes so far as to assert that with a good method of heating the air, not only can all the losses due to the production and the transmission of the compressed air be made good, but also that it will actually contain more useful energy at the motor than was expended at the central station in compressing it.
According to Professor Riedler, from 15 to 20 per cent. above the power at the central station can be obtained by means at the disposal of the power users, and it has been shown by experiment that by heating the air to 250 deg. Cent. an increased efficiency of 30 per cent. can be obtained. Better results than those heretofore obtained may, therefore, be confidently expected with a more perfect and economical application of the fuel in heating the air, and a better means of regulation in admitting it to the motors. In his report Professor Riedler indicates a method by the use of which he considers considerable advantages may be secured. This is the heating the air in two stages instead of at one operation, and passing it through two motors, to the first of which the air is admitted heated only to a moderate extent; the exhaust from this motor then passes into a second heater and thence into the second motor. A series of experiments with this arrangement were recently carried out.
The consumption of air per brake horse power was reduced from 812 cubic feet per hour, a favorable duty in the single motor, to 720, and in the best result to 646 cubic feet with the two motors and double heaters. It should be added that these trials were carried out with steam engines but ill adapted for the purpose. It is to be regretted that the experiments of Professor Riedler could not have been conducted with more perfect appliances, but it must be borne in mind that the utilization of compressed air, especially as regards the motors, is still in a very imperfect stage, and that a great deal remains to be done before the maximum power available at the motor can be obtained. Investigations in this direction for a considerable time to come must be directed, therefore, toward improving the design and construction of the motors and the treatment of the air at the point of delivery into the engine.
A large number of motors in use among the subscribers to the Compressed Air Company, of Paris, are rotary engines developing one horse power and less, and these in the early times of the industry were extravagant in their consumption, to a very high degree. To some extent this condition of things has been improved, chiefly by the addition of better regulating valves to control the air admission.
As altered, the two horse power rotary motors, when employed as cold air engines, a method often desired in special industries, consume 1,059 cubic feet per hour and per indicated horse power; with a moderate degree of heating, say to 50 deg. Cent., this consumption falls to 847 cubic feet. The efficiency of this type of rotary motors with air heated to 50 deg. may now be assumed at 43 per cent., not a very economical result, it is true, and one that may be largely improved, yet it is evident that with such an efficiency the use of small motors in many industries becomes possible, while in cases where it is necessary to have a constant supply of cold air, economy ceases to be a matter of the first importance.
Some useful results were obtained with compressed air used in crank engines; it is to be regretted that with this, also, apologies have to be made for the imperfect design and construction; they were old steam engines, some of those of two horse power losing from 25 to 30 per cent. by their own friction; some of the others tried, however, were far better, a newer type losing only from 8 to 10 per cent., while the 80 horse power referred to below showed an efficiency of 91 per cent. From these trials Prof. Riedler deduces—assuming 85 per cent. efficiency—a consumption of 611, 752, and 720 cubic feet per brake horse power. It is very evident from the foregoing that the Compressed Air Company, of Paris, will never do itself justice until as much thought and care has been devoted to the economical use of the motive power as has been expended in the means of producing it, and Professor Riedler's recent investigations should be especially useful in this respect. The question has indeed attracted the attention of more than one manufacturer, and reference is made to a particular type of small rotary motors which are being constructed by MM. Riedinger & Co., and which is stated have given very excellent results. These engines were specially used for working sewing machines and developed on the brake an efficiency of 34.07 and 51.63 foot pounds per second. Trials were made with a half horse power variable expansion Riedinger engine.
TRIALS OF A SMALL ROTARY RIEDINGER ENGINE. ___________ Number of trials. I. II. ________ __ __ Initial air pressure. lb. per square inch 86 71.8 " temperature. deg. Cent. +12 +170 Ft. pounds per second measured on the brake. 51.63 34.07 Revolutions per minute. 384 300 Consumption of air for one horse power per hour. 1,377 988 ________ __ __
TRIALS OF A 0.5 HORSE POWER RIEDINGER ROTARY ENGINE. ____________ Number of trials. I. II. III. IV. _______ _ _ _ __ Initial pressure of air. lb. per sq. in. 54 69.7 85 71.8 " temperature of air. deg. Cent. 170 180 198 8 Final " " " 25 20 ... 25 Revolutions per minute. 335 350 310 243 Foot pounds per second measured on brake. 271 477 376 316 Consumption of air per horse power and per hour. 883 791 900 1,148 _______ _ _ _ _
TRIAL OF AN 80 HORSE POWER (NOMINAL) FARCOT STEAM ENGINE. R p e e I Consumption of v r n Temperature air per horse o d h p of air. power and per l m i o o hour. u i c r w t n a s e Motor. i u t e r Admission Exhaust. Nominal Brake o t e . horse horse n e d power. power. s. deg. C deg. C Nominal 80 horse 54.3 72.3 129 21 469 517 power single 54.3 72.3 152 29 437 475 cylinder Farcot 54.0 72.3 160 35 424 465 engine. 40 65.0 170 49 438 477
These motors, it may be assumed, represent the best practice that has been obtained up to the present time in the construction of compressed air motors; with the smallest of them, indicating about one-tenth of a horse power, the consumption of air, when admitted cold, was 1377 cubic feet and 988 cubic feet when the air was heated before admission. The half horse power engine consumed 1148 cubic feet of cold air, and of heated air 791 cubic feet per horse power and per hour. It should be mentioned that these, the most valuable and suggestive of all the trials carried out by Professor Riedler, were conducted with the greatest care, two distinct modes of measuring the air supplied being followed on two occasions for each test; it may therefore be considered that the results given are absolutely correct. The trials were made with an old single cylinder Farcot engine, nominally of 80 horse power, but indicating over 72.3. With this engine the consumption of air varied from 465 to 517 cubic feet, the larger consumption being due to the lower temperature (129 deg. Cent.) to which the air was raised before admission; in the most economical result the temperature was 160 deg. Cent. The volumes of air referred to are, of course, in all cases taken at atmospheric pressure.
Among the important losses that have to be reckoned with in every system of distributing motive power from a central station—whether by steam or by electricity, water, or compressed air—losses must occur in the mains by which the power generated is transferred from the point of production to that of consumption. In the case we are now considering very careful tests were conducted in 1889 by Professor Kennedy, to whose report we have already referred. Since that time important changes have been made by the Compressed Air Company, at Paris, in the details of distribution, and on this account the later investigations of Professor Riedler on the losses due to this cause are of special interest.
Before its admission into the mains a certain loss occurs at the St. Fargeau station, in the large reservoirs to which the air is delivered from the compressors. This question of preliminary storage was one that received considerable attention when the designs of the new station on the Quai de la Gare were being considered. It was intended to construct very large receivers in the basement of the station, and the foundations for these were even commenced. It was decided, however, that for the 10,000 horse power which is to form the first section of the new station, and for which the complete system of mains has already been laid down, storage reservoirs would be unnecessary, and a saving both in first cost and subsequent loss of air would be effected. The length of mains of 19.69 in. diameter is so considerable that they will contain at all times a sufficient reserve of air to prevent any irregularities in pressure at the motors.
With reference to these mains it may be mentioned that, unlike the 11.81 in. conductors of the St. Fargeau system, of which 17 kilometers are laid in the Paris subways, the new mains are entirely laid in the streets, it having been found impossible to make room for these large pipes in the subways already crowded with telegraph and telephone wires, water mains, etc.
Professor Riedler investigated the two causes of loss in the mains—leakage and resistance. It was superficially evident that the mains of the old system were so well laid, and the joints so well designed, that the loss from leakage was never a serious one. In order, however, to ascertain the amount accurately, a series of careful experiments were carried out by Professor Gutermuth with the 11.81 in. mains of the St. Fargeau system.
EXPERIMENTS ON LEAKAGE IN MAINS.
- L P A Air Pressure Loss of o e i in Mains. Pressure. s r r - - s B C D System of Mains Length. e T o e e N Tried. g r At f n l u A i o i End During Per t i m t n f a of Trials Hour. A . v b n l Trials. i e e i s r o r r n . f e g d + -+ -+ -+ -+ + + - yards. atm. atm. 1 Southern reseau to Place de la Concorde. 9,980 6.5 6.0 0.5 1.5 3 2 Total reseau 18,500 6.9 5.9 1.0 1.5 6.3 3 To Place de la Concorde 9,980 7.0 6.43 0.57 0.75 2.16 4 Total reseau 18,500 6.7 5.28 0.88 1.32 5.5 5 Northern reseau to Rue de Belle- ville. 1,530 6.0 5.0 1.0 0.6 2.3 6 To the Rue des Pyrenees. 600 6.1 3.7 2.4 0.56 2.2 -
These trials refer to the mains running from the St. Fargeau station to the Place de la Concorde, a length of 9.142 kilometers; to the whole system of mains, 16.5 kilometers; to the northern mains running from St. Fargeau to the Rue de Belleville, 1.4 kilometers; and from St. Fargeau to the Rue des Pyrenees, 6.5 kilometers. It will be seen from the figures given in the table that the actual loss is small, and it is stated that this is due chiefly to the elastic joint employed throughout the system, excepting in the Rue de Belleville, where rigid couplings are used, and continual trouble is experienced from loss by leakage. In all cases the losses given are the maximum, which only occur under the most unfavorable conditions.
It was found, during the first, second, and fourth tests, that considerable leakage occurred between the St. Fargeau central station and the Rue de Belleville. During the trials two and four, an uncertain amount of loss occurred from the consumption of air required to work the pneumatic clocks, and also motors in the circuit, that could not be stopped. The tests two and four include all losses in the service pipes, as well as the mains.
The production of compressed air at the central station is assumed at 30,000 cubic feet per hour (atmospheric pressure), and in all cases the loss in the mains is taken as a percentage of the total production.
The losses due to resistance in the mains were also examined with great care, over independent sections, as well as through the complete reseau. During the early part of these trials, an unusual and excessive loss was recorded, the cause of which could not be at first ascertained. At intervals along these mains are placed a number of water reservoirs which receive the water injected into the mains; in addition to these the direct flow of the air is interrupted by numerous siphons, the stop valves to branches, etc. Investigation showed that the presence of these reservoirs created considerable resistance on account of an increased and subsequently reduced section. The exact loss from this cause was, therefore, carefully measured, as well as the losses existing in the mains not so interrupted. The results show that the loss by expansion at one reservoir, when the speed of the air flow was 23 ft. per second, was equal to 0.15 atmosphere; with a speed of 29 ft. 6 in. per second, it amounted to 0.2 atmosphere.
Therefore, the presence of five such reservoirs would cause a loss in pressure equal to one atmosphere. This very undesirable arrangement is not repeated in the new system, the sumphs being connected in such a way as not to modify the section of the tube, nor consequently the pressure of the air. The presence of the siphons and stop valves did not seem to affect the pressure to any measurable extent. The following table contains a list of the more important mains tested, and it may be mentioned that the resistance, due to the reservoirs, was at first partially included. The trials were carried out while the mains were not being drawn upon by subscribers.
- Section of Mains Tested. Length. No. of Tests. - yards. From the central station to the end of reseau and back to central station by return circuit 18,100 7 From the central station to the Rue Fontaine au 14,600 / 3 Roi / 9,900 4 From the central station to the Rue de la Charonne 9,490 5 From the Rue de la Charonne to Fontaine au Roi 4,770 3 From the central station to the Avenue de la Republique 1,860 8 Various trials on different lengths of mains 770 to 8,000 11 -
Over the whole system of 16.5 kilometers, which was also tested when no air was being taken off, there were four reservoirs of considerable size, and which offered a large resistance with a corresponding loss of pressure; on the line there were also 23 siphons and 42 stop valves.
These trials were repeated several times to secure accuracy, and the speed of the air was brought to 49 ft. a second. The results obtained in one of these trials may be taken as an example. The main between the Rue St. Fargeau and the Fontaine au Roi, on which there are no collecting reservoirs, but three siphons and eight stop valves, gave, with an average speed of 21 ft. 3 in., a loss in pressure of 0.05 atmosphere for each kilometer of main.
From these experiments it would appear that, assuming a speed of 21 ft. per second, a loss in pressure of one atmosphere would correspond to a distance of 20 kilometers; that is to say, a central station could extend its mains on all sides with a radius of 20 kilometers, and the motors at the ends of the lines would receive the air at a pressure 15 lb. less than at the central station. Professor Riedler states that as an actually measured result, the velocity of the air through the mains of the St. Fargeau system is 19 ft. 8 in. per second, and that the loss in pressure per kilometer is 0.07 atmosphere. From this it follows that including the resistances due to the four reservoirs, and other obstructions actually existing, an allowance of one atmosphere loss on a 14 kilometer radius is ample. By increasing the initial pressure of the air, much better results can be obtained, and future attention in practice should be devoted to this point. The amount of work required to compress air does not increase in the same ratio as the pressure, and for this reason considerable economy can be effected at the first stage, and the loss in the mains will be reduced.
Passing to another point of the same subject, Professor Riedler considers the best dimensions that should be given to the mains. Resistance decreases with an increase in the diameter of these and in direct ratio to their diameter; for this reason—still assuming a pressure corresponding to a velocity of 20 ft. per second—with a fall of one atmosphere, a length of 40 kilometers could be succesfully worked.
The mains of the new reseau for the Quai de la Gare station are 19.69 in. in diameter; they are built up of steel plates riveted, and this Professor Riedler considers to have been a serious error on account of the extra resistance offered by the large number of rivet heads.
The following may be taken as a brief summary of Professor Riedler's conclusions: Recent improvements in central station practice have resulted in an increased efficiency of about 30 per cent. in the compressors, but this benefit can only be realized when the new station is in operation. That the small and very imperfect air engines in use on the system give an efficiency of 50 per cent., while with ordinary steam engines driven by air an efficiency of 80 per cent. can be reached with a very small expenditure of fuel for heating the air before admitting it into the motor. That special attention should be given to the improvement of air engines, and that with increased initial pressures at the central station the distance of the transmission can be very considerably augmented. Finally, Professor Riedler claims that power can be transmitted by compressed air more conveniently and more economically than by any other means.
* * * * *
[Continued from SUPPLEMENT, No. 802, page 12810.]
THE BUILDERS OF THE STEAM ENGINE—THE FOUNDERS OF MODERN INDUSTRIES AND NATIONS.[1]
[Footnote 1: An address delivered at the Centennial Celebration of the American Patent System, Washington, April, 1891.]
By Dr. R.H. THURSTON, Director of Sibley College, Cornell University.
Papin, Worcester, Savery, were the authors of the period of application of the power of steam to useful work in our later days. The world was, in their time, just waking into a new life under the stimulus of a new freedom that, from the time of Shakespeare, of Newton, and of Gilbert, the physicist, has steadily become wider, higher, and more fruitful year by year. All the modern sciences and all the modern arts had their reawakening with the seventeenth century. Every aspect of freedom for humanity came into view in those days of a new birth. Both the possibility of the introduction of new sciences and of new arts and the power of utilizing all new intellectual and physical forces came together. The steam engine could not earlier have taken form, and, taking form, it could not have promoted the advance of civilization in the earlier centuries. The invention becoming possible of development and application, the promotion of the arts and of all forms of human activity became a possible consequence of its final successful introduction into the rude arts that it was to so effectively promote and improve.
But the work of these inventors was in itself but little more important than that of the Greek inventor of the steam aelopile, for each brought forward a machine which was, from a business point of view, utterly impracticable, and which, in each case, only served to show that a better device might prove useful and lead the way to its introduction. The merit of the inventors of the eighteenth century was that they were able to lead the way, to point out the path to success, to furnish evidence of the value of the coming, crowning invention. The "fire engines," as they were then called, of these now famous men were merely contrivances by the use of which the pressure of confined steam of high tension could be brought to act on the surface of a mass of confined water, forcing it downward into pipes through which it was led off and upward to a higher level; and thus a mine could be drained, ineffectively and expensively to be sure, but vastly more satisfactorily than by the animal power of the time. The machine of Savery was the best of all; but that was only a somewhat improved and manageable rearrangement of the engines of Papin and Worcester. And, after all, Papin, the greatest man of science perhaps of his time, died in poverty; Worcester languished in prison his whole life, and the later efforts of his widow brought nothing by way of a return for his invention; nor did either they or their successor, Morland, make the introduction of the engine either general or remunerative.
Savery, coming on the stage at more nearly the right time to seize upon an opportunity, gained more than either of his predecessors; but we have no evidence that he ever acquired any large compensation or met with any remarkable business success in the introduction of the rude engine which bore his name; nor did Desaguliers, the great philosopher, or even Smeaton, the great engineer, of the later years of that century, make any great success of it. It was reserved for Watt to reap the harvest. But, though he so effectively reaped where his predecessors had sown, Watt is not the greatest of the inventors of the steam engine, if we rate his standing by the magnitude of the improvement which marked his reconstruction of the engine.
It was NEWCOMEN who made the modern steam engine.
When Newcomen came forward the labors of Worcester in Great Britain had sufficed to attract the attention of all intelligent men to the character of the problem to be solved, and to convince them of its importance and promise. The work of Savery had shown the practicability of the solution of the problem, both in mechanics and finance. He succeeded, though under great disadvantages and comparatively inefficiently. Once the task had been performed, though ever so rudely, the rest came easily and promptly. The defects of the Savery system were at once recognized; its great wastes of heat and of steam were noted, and the fact that they were inherent in the system itself was perceived. A complete change of type of machine was obviously requisite; it was this which constituted the greatest invention in the whole history of the steam engine, from Hero's time to our own; and to Newcomen we owe more than to any other man who ever lived, the value of the invention itself being considered, and the importance of the services of its introducer being left out of consideration. No such complete and vital improvement and modification of the machine has ever been effected by any other man, Watt and Corliss not excepted. Newcomen and his comrade Calley—we do not know how the honors should be divided—produced the modern steam engine. Its predecessor, the Savery engine, had been a mere steam "squirt." Newcomen constructed an engine. Savery built a simple combination of cylindrical or ellipsoidal vessels which wastefully and at once performed all the several offices of engine, pump, condenser, and boiler; Newcomen divided the several elements among as many parts, each especially adapted to the performance of its task in the most effective manner—the condenser excepted; for that was Watt's principal invention—and thus produced the first steam engine in the modern sense of that term.
It was Newcomen, not Watt, who gave us the train of mechanism that we now call the steam engine. It is to Newcomen, rather than Watt, that we owe the highest honors as an inventor in this series of the most important of all the products of the inventive genius of mankind. Newcomen brought into existence a new, the modern, type of engine, and effected the greatest revolution that has been recorded in the history of the arts. Without Newcomen, there might have been no Watt; without Watt, there very possibly may not even yet have been brought into existence that giant of our time, whose mighty powers are employed more effectively than ever those of Aladdin's genii, in building palaces, in transporting men and material, in doing the work of the whole world; promoting the welfare of the race, in a single century, more than had all the forces of matter and mind together in the whole previous history of the world. Newcomen laid down a foundation beneath our whole economic system, out of sight, almost, but the essential base, nevertheless, on which Watt and his successors have carried up the great superstructure which seems to us to-day so imposing; which is so tremendous in magnitude, importance, and result. If to any one man could be assigned the credit, it is Newcomen who is to be considered the inventor of the steam engine.
James Watt, indisputably the great inventor that he was, found the steam engine ready to his hand, applied himself to its improvement, and made it substantially what it is to-day. His most important work, the most unique service performed by him, was, however, that of its adaptation and introduction to do the work of the world. James Watt was the inaugurator of the era of refinement of the machine already invented, and the greatest of its builders and distributors. His inventions were all directed to the improvement of its details, and his labors to its introduction and its application to the myriad tasks awaiting it. By the hands of Watt it was made to pump water, to spin, to weave, to drive every mill; and he it was who gave it the form demanded by Stephenson, by Fulton, by the whole industrial world, for use on railway and steamboat, and in mill and factory, throughout the civilized countries of the globe. It was this great mechanic who showed how it might be made to do its work with least expense, with highest efficiency, with greatest regularity, with utmost concentration of power.
The grand secret of his success was historical and economic, as much as scientific and mechanical. He brought out his inventions just when the world was economically and historically ready for them. The age of authority was past, that of freedom was come; the period of political and ecclesiastical tyranny was gone by, and that of the spontaneous development of man was arrived. The great invention was offered to a world ready and needing it, and, more than all, competent, for the first time in history, to make and use it.
James Watt was himself a product of the modern scientific spirit. He was a man so constituted mentally that he could apply scientific methods to problems which his logical and clairvoyant mind could readily and exactly formulate the instant he was led to their consideration in the natural course of his progress. He was the ideal great inventor and mechanic. With inventive genius he combined strong common sense—not always a quality distinguishing the inventor—clear perception, breadth of view, and scientific method and spirit in the treatment of every question. His natural talent was re-enforced by an experience and an environment which led him to develop these ways and this mental habit. His trade was that of an instrument maker, his position was that of custodian and repairer of the apparatus of Glasgow University. He had for his daily companions and stimulus the great men and ozonized atmosphere of that famous institution. He kept pace with advancing science, and was imbued, both naturally and through contact with its promoters, with that ambition and those aspirations which are the life element of all progress, whether scientific or other. He was aware of the nature of the problems seeking solution at the time, and familiar with the state of his own art and that of the great mechanicians about him. Everything was favorable to his progress, so soon as he should be given an opportunity to take a step in advance and to come into sight at the front. The man and the time were both ready, and all conditions, internal and external, social and personal, were favorable to his development.
The invention upon which Watt was to improve was at his hand. A word in regard to its status at the moment will throw some light upon that of Watt and his creation. Newcomen had, as we have seen, produced the modern type of steam engine as an original and wholly novel invention. But this machine, marvelous as an advance upon pre-existing forms of the steam engine, was still, as seen in the light of recent knowledge and experience, exceedingly defective. The purpose of a steam engine is to convert into usefully applicable power the hidden energy of fuel, stored ages ago in the earth, by transformation, through the action of vegetation, from the original form, the heat of the sun, into an available form for reconversion, through thermodynamic operations. In this process of reconversion, whatever the nature of the machine used in the operation, there are invariably wastes, both of heat required for conversion into power and of the power thus produced. That machine which effects the most complete transmutation of the heat supplied it into mechanical power, which wastes the least amount of heat supplied and of power produced, is the best engine, and constitutes an advance over every other.
It was this reduction of wastes that made the Newcomen engine so much superior to that of Savery. The latter was by far the simpler and less costly construction; but its enormous losses, both of heat and of power, mainly the former, however, made it an extravagant expenditure of money to buy and use it. The Newcomen engine, costly and cumbrous, comparatively, nevertheless wasted so much less heat and steam and fuel that no one could afford to buy the cheaper machine. Before considering what Watt accomplished, we may find it profitable to examine into the nature of the wastes which characterized this later and better machine on which he effected his improvements.
The Newcomen engine consisted of a steam boiler, a steam cylinder, a beam and a set of pumps. By making the boiler do its work separately, the engine acting independently, and the pumps as a detached portion of the mechanism, this inventor had reduced to an enormous extent those wastes of heat and of steam and of fuel which were unavoidable in the older machines in which all these parts were represented by a single vessel, or by two at most, in each element. In the Savery engine, the steam entering first heated up the interior of the working vessel to its own temperature, and held it at that temperature in spite of the cooling influence of the water present. This consumed large quantities of heat. It then was compelled to surrender probably much greater quantities still to the water itself, coming in direct contact as it did with its surface. If the water was agitated, either by the currents produced during its ingress or by the impact of the steam entering the vessel, this heating action penetrated to considerable depths and perhaps even warmed the whole mass very far above its initial temperature. This constituted another and a very serious loss. Then, again, as the water was gradually driven out of the containing vessel by the steam pressing on its surface, new portions of the vessel and new masses of water were continually brought in contact with the hot steam, taking its full temperature, and thus, often, probably, finally heating the whole mass of the forcing vessel, and a large proportion of the water as well, up to the temperature, approximately at least, of the steam itself. Thus in many instances, if not always, vastly more heat and steam were wasted, in this undesirable heating of water and forcing vessel, than were usefully employed in the legitimate work of raising the water to a higher level. In fact, in some cases in which these quantities were measured, the wastes were one hundred times as much as the work done. One per cent. of the heat supplied did the work; while ninety-nine per cent. was thrown away. One dollar or one shilling expended for fuel to do the work was accompanied by an expenditure of ninety-nine dollars or shillings thrown away, because of the imperfections of the system and machine. The whole history of the development of the steam engine has been one of gradual reduction of these wastes; until to-day, our best engines only compel us to spend five dollars for wastes to each dollar paid out for useful work. A business man would think that amply extravagant, however, and the man of science is continually seeking methods of evading these losses, a large proportion of which are now apparently unavoidable in heat engines, by finding some new system of heat and energy transformation.
Watt was the instrument maker and repairer at Glasgow University in the year 1763. His companions were, among others, the professors of natural philosophy and of mathematics in the university. Their conversation and their frequent presentation of practical and scientific questions and problems stimulated his naturally inquiring and inventive mind to the pursuit of a thousand interesting and promising schemes for the improvement of existing methods and machinery. Dr. Robison, then a student, suggested the invention of a steam carriage for use on common roads, and the young mechanician at once began experiments that, resulting in nothing at the time, were nevertheless continued, in one or another form, until all modern applications of steam came into view. Dr. Black taught Watt chemistry, then a newly constructed science, and led him on to the discovery, finally made by them independently, of the fact and the magnitude of the latent heat of steam; the discovery coming of a series of scientifically planned and accurately conducted investigations, such as the man of science of to-day would deem creditable. The treatises of Desaguliers and others on physics gave Watt a knowledge of that domain of natural phenomena which stood him in good stead later, when he attempted to apply its principles to the reduction of the wastes of the steam engine.
It was while at Glasgow University, working under such influences and in such an atmosphere of intellectual activity, that the accident of the Newcomen model engine needing repair brought to the mind of Watt the opportunity which, availed of at once, made him famous and gave the world its greatest aid, its most powerful servant. The observing mind of the great mechanic immediately noted its defects, sought their causes, found their remedy. He discovered, at once, that the quantity of steam entering the cylinder of the little engine has four times the volume of the cylinder receiving it: in other words, three-fourths of that steam must be condensed immediately on entrance. This meant, evidently, that only one-fourth of the steam supplied was utilized, and even then inefficiently, in doing its work. The reason of this was as easily seen, immediately the fact was revealed. As Watt himself expressed it, the causes of this loss, causes which would obviously be exaggerated in a small engine, were: "First, the dissipation of heat by the cylinder itself, which was of brass and both a good conductor and a good radiator. Secondly, the loss of heat consequent upon the necessity of cooling down the cylinder at every stroke in producing the vacuum. Thirdly, the loss of power due to the pressure of vapor beneath the piston, which was a consequence of the imperfect method of condensation." This much determined, the next step looked toward the confirmation of his conclusions and the remedy of the defects.
To meet the first difficulty he made a cylinder of wood, soaked in oil and baked, a non-conducting and non-radiating material. Then he was able to determine with some accuracy the quantities of steam and injection water used in the engine; and a comparison with the original cylinder and its operation showed that not only four times the quantity of steam, but also four times the amount of injection water was used as was necessary, assuming wastes checked. Further scientific research on the part of Watt gave him measures of specific heats of the metals and of wood, the specific volumes of steam at various working pressures, the evaporative efficiency of boilers, the pressures and temperatures of steam in the boiler under specified conditions, the quantities of steam and of water required for the operation of his little condensing engine.
Then came his enunciation of the grand principle of economy in the construction and operation of the steam engine: "Keep the cylinder as hot as the steam which enters it," as he expressed it. This was Watt's guiding principle, as it has been that of all his successors in the improvement of the economic performance of the steam engine and of all other heat engines. The great source of waste is the dispersion of heat, uselessly, which should be applied to the production of work by its transformation, thermodynamically, into the latter form of energy. The second form of waste is that of power thus produced in the unprofitable work of moving the parts of the engine itself; and the third is that of heat by transfer, without transformation, by conduction and radiation to surrounding bodies. In modern engines, the latter is but three or five per cent., in the best cases; the second waste constitutes perhaps ten per cent.; while the first of these losses amounts very usually to seventy per cent., of which last one-third or one-fourth is of the kind discovered by Watt, the rest being the thermodynamic waste incident to all known methods of operation of heat engines, and apparently unavoidable. In our very best and largest engines, the waste found by Watt to constitute three fourths of all heat supplied has been brought down to ten per cent., a fact which well exemplifies the advances made since his time of apprenticeship by himself and his successors of this nineteenth century. The steam engine of to-day, in its most successful operation, gives us twenty-five times as much power from a pound of coal as did the engine that the great inventor sought to improve: this is the magnificent fruit of that one discovery of James Watt, and of application of the simple principle which he so concisely and clearly stated.
The method adopted by Watt to secure a remedy, so far as practicable, of this defect of the older machine was as simple and as perfect as was the principle which it embodied. He first removed from the cylinder the prime source of its wastes; providing a separate condenser, and thus avoiding the repeated chilling of its surfaces by the cold water used in condensing the steam at exhaust, and also permitting its strokes to be made with far greater frequency, thus giving less time for cooling by the influence of the remaining vapors after condensation. He next went still further, and provided the cylinder with a closed top, keeping out the air, and a "jacket" of hot boiler steam to keep it as hot as the steam which entered it. These were the two great improvements which converted the first real steam engine into an economical form of heat engine and essentially finished the work so grandly begun by Newcomen and Calley. These changes gave us the modern steam engine; and these are Watt's first and greatest, but by no means only, contributions to the production of the modern world with all its comforts, its luxuries and its opportunities for material, intellectual and moral advancement of individual and of race. His work was to this extent complete in 1765.
But Watt did not stop here. There still remained for him the no less important and the, in some senses, still more imposing, work of finding employment for the new servant of mankind and of setting it at its work of giving the human arm a thousand times greater strength, to the mind of man uncounted opportunities to promote the advancement of knowledge, of civilization, of every good of the race. His was still the task of adapting the new machine to all the purposes of modern industry. It had been hitherto confined to the task of raising water from the depths of the mine; it was now to be harnessed to the railway train; to be made to drive the machinery of the mill, to apply its marvelous power to the impulsion of the river boat and ocean steamer; to furnish energy, through endless systems of transfer and use, to every kind of work that man could devise and should invent. All this meant the giving of the machine forms as various as the purposes to which it was to be devoted. It had previously only raised and depressed a rod; it must now turn a shaft. It had then only operated a pump; it must now turn a mill, grind our grain, spin our threads, weave our cloths, drive our shops and factories, supply the powerful blast of the iron furnace. It must be made to move with the utmost conceivable regularity, and must, with all this, do its work in the development of the hidden energy of the fuel, with the greatest possible economy, through the expansion of its steam. All this was achieved by James Watt.
The invention of the double-acting engine, in which the impulsion of the steam is felt both in driving the piston forward and in forcing it backward, both upward and downward, the application of its force through crank and fly wheel, the creation of an automatic system of governing its speed, and the discovery of the economy due to its complete expansion, were all improvements of the first magnitude, and of the greatest practical importance; and all these were in rapid succession brought into existence by the creative mind that had apparently been brought into the world for the express purpose of giving to the hand of man this mighty agent, to perfect the mightiest power that mind of man has yet conceived.
But to do the rest required more than inventive genius and mechanical skill. It demanded capital and the stored energy of labor and genius in other fields, directed by the mind of a great "captain of industry." This came to Watt through Matthew Boulton, a manufacturer of Birmingham, whose father and ancestors had gradually and toilsomely, as always, accumulated the property needed for the prosecution of a great business. The combination of genius and capital is always an essential to success in such cases; and good fortune, a Providence, we may well say, brought together the genius and the capitalist to do their work, hand in hand, of providing the world with the steam engine. Hand in hand they worked, and all the world to-day, and the race throughout its future life, must testify gratitude for the inexpressible obligations under which these two men have placed them, doing the work of the world.
Boulton & Watt, the capitalist with the inventor, gave the world the steam engine, finally, in such form and in such numbers that its permanent establishment as the servant of man was insured. The capitalist was as essential an element of success as was the inventor, and, in this instance, as in a thousand others, the race is indebted to that much-abused friend of the race, the capitalist, for much that it enjoys of all that it desires. The industry and patience, the skill and the wisdom required for the accumulation of this energy stored for future use in great enterprises is as important, as essential, as inventive power or any other form of genius. Talent and genius must always aid each other. This firm was established in 1764 and its main resources, aside from the bank account, were Watt's patent, about expiring, and Watt's genius, and Boulton's talent as a man of business. The patent was extended for twenty-four years, the new inventions of Watt, now beginning to pour from his prolific brain in a wonderful stream, were also patented, and the whole works were soon employed upon the construction of engines for which numerous orders soon began to pour in upon the now prosperous builders. The patent law established Boulton and Watt and the firm paid back the nation with handsome usury, giving it unimaginable profits indirectly through its control of the work of the world and large profits directly through the business brought them from all parts of the then civilized globe. There has never, in the history of the world, been a more impressive illustration of the value to a nation of that generous public policy, that simply just legislation, which gives to the man of brain control of the products of his mind. For a hundred years, Great Britain has, largely through her encouragement of the inventor and her protection of his mental property by securing the fruits of his labors, in fair portion, to him, gained the power of dictating to the world and has gained an advance that cannot be measured. Watt and Arkwright and Stephenson and Crompton and their ilk, protected by their government and its patent laws, made their country the peaceful conqueror of the world. The story of the work of the inventor is a poem of mighty meaning and of wonderful deeds. The inventor proved himself a mightier magician than ever the world had seen.
"A creature he called to wait on his will, Half iron, half vapor—a dread to behold; Which evermore panted, and evermore rolled, And uttered his words a millionfold."
Such was the outcome of this grand modern "trust," a combination of the wisest legislation, the most brilliant invention, and the most wisely applied capital. There are "trusts" of which the outcome is most beneficent.
Since the days of Watt, the improvement of the steam engine and the work of inventors has been confined to matters of detail. All the fundamental principles were developed by Watt and his predecessors and contemporaries and it only was left to his successors to find the best ways of carrying them into effect. But these matters of detail have been found to involve opportunities to make enormous strides in the direction of securing improved efficiency of the machine. The further application of the principle which led Watt to his greatest inventions; of the principle, keep the cylinder as hot as the steam which enters it, of that which he enunciated relative to the advantage of expanding steam, and of that affecting the regulation of the machine; have reduced the costs of steam and of fuel to a small fraction of their earlier magnitude. One ton of engine to-day does the work of eight or ten in the time of Watt: one pound of fuel or of steam gives to-day ten times the power then obtained from it. A steamship now crosses the Atlantic in one-eighth the time required by the famous "liner" of the "Black Ball Line." The wastes of the engine have been brought down from above eighty per cent. to eight; and a half-ounce of fuel on board ship will now transport a ton of cargo over a mile of ocean.
FREDERICK E. SICKELS gave us the first practicable form of expansion gear in 1841; GEORGE H. CORLISS gave a new type of engine of marvelous perfection and economy in 1849; Noble T. Green, Wm. Wright and many less well known but no less meritorious inventors have since done their part in the transformation of the old engine of Watt into the modern wonder of concentrated and economical power, and marvel of accurate and beautiful design and workmanship. The "trip cut-off," with reduced clearances, increased boiler pressure, higher rates of expansion, accelerated speeds of engine, better construction in all respects, as well as improved design, have enabled us to avail ourselves to the utmost of the principles of Watt, and our mills, our railways, our steamers and our fields, even, have gained almost as extraordinarily by these advances, since the days of the great inventor, as through his immediate labors.
With the introduction of the new form of older energy, electricity, with the reduction of the lightning into thraldom, has now come a new impulse affecting all the industries. Through its mysterious, its still unknown action, steam now reaches out far from its own place, driving the electric car along miles of rail; giving light throughout all the country about it, turning night into day, and repressing crime while encouraging legitimate labor, reaching into distant chambers and every little workshop, to offer its powerful aid in all the distributed work of cities. Without the steam engine there would be little work available for electricity, but the appearance of this, the latest and most useful handmaid of steam, has given the engine work to do in an uncounted number of new fields, has called in the inventor once more to adapt steam to its new work. The "high-speed engine" is the latest form of the universal helper. And such has been the readiness and the intelligence of the contemporary inventor that we now have engines capable of turning their shafts three hundred rotations a minute and without a perceptible variation of velocity, whatever the change of load or the suddenness with which it is varied. In the days of Watt a fluctuation of five per cent. in speed was thought wonderfully small; in those of Corliss, the variation was restricted to two per cent. and we wondered at this unanticipated success. To-day, thanks to Porter and Allen, to Hartnell, to Hoadley, to Sims, to Thomson, to Sweet, to Ide, and to Ball, we have seen the speed fluctuation restricted to even less than one per cent. of its normal average.
The inventors of the steam engine are, through their representatives of to-day, according to the statisticians, doing the equivalent of twelve times the work of a horse, for every man, woman and child on the globe. We have not less, probably, than a half million of miles of railway, transporting something over 150,000,000,000 of tons a mile a year. A horse is reckoned to haul a ton weight about six and a half miles, day by day, by the year together. In the United States, it is reckoned that the steam engine, on the railways alone, hauls a thousand tons one mile, for every inhabitant of the country, every year, or, if it is preferred to so state it, a ton a thousand miles. This is the way in which the East and the West are, by the inventors of the steam engine, enabled to help each other. This costs about $10 each individual; it would require some 25 millions of horses to do the work, and would cost about $1,000 a family, which is more than twice the average family earnings.
Dr. Strong, in that remarkable book, "Our Country," says: "One man, by the aid of steam, is able to do the work which required two hundred and fifty men at the beginning of the century. The machinery of Massachusetts alone represents the labor of more than 100,000,000 men, as if one-half of all the workmen of the globe had engaged in her service." And again: "Some thirty years ago, the power of machinery in the mills of Great Britain was estimated to be equal to 600,000,000 men, or more than all the adults, male and female, of all mankind." Mr. Gladstone estimated that the aggregation of wealth on the globe during the whole period from the birth of Christ to that of Watt was equaled by the production in twenty years, at the middle of this century, with the aid of machinery driven by the fruit of the brain of the inventors of the steam engine. We may probably now safely estimate the former quantity as rivaled in less than five years, while, since the birth of Watt and his engine, and the production of the spinning mule, the power loom, the cotton gin and our own patent system and its marvelous mechanism, all events of a century ago, we may estimate that they have, together, accomplished more in this period which we now celebrate than could have been done in a millenium of milleniums without these now subjected genii. But the power behind all these curious inventions and their work is that of steam. The steam engine even supplies power to the telegraph and transports words and thought as well as cotton bales and coal.
And now what has this combination of legislation for private protection and public good, of a genius producing great inventions, and of the accumulated capital of earlier years, brought about?
It has given us the best fruits of science in permanent possession. The study of science invariably aids, in a thousand ways, the progress of mankind. It gives us new conceptions of nature and of the possibilities of art; it promotes right ways of work and of study; it teaches the inventor and the discoverer how most surely and promptly to gain their several ends, it gives the world the results of all acquired knowledge in concrete form. This one instance which we are now especially interested in contemplating has performed more wonderful miracles than ever Aladdin's genii attempted. One man, with a steam engine at his hand, turns the wheels of a great mill, drives forty thousand spindles, applies a thousand horse power to daily work in the spinning of threads, the weaving of cloth, the impulsion of a steamboat, or the drawing of great masses of hot iron into finest wire. This puny creature, his mind in his finger tips, exerts the power of ten thousand men, working with muscle alone, and, aided by a handful of women, boys and girls, clothes a city. A half dozen men in the engine room of an ocean steamer, with a hundred strong laborers in the boiler room and on deck, transports colonies and makes new nations, brings separated peoples together, unites countries on opposite sides of the globe, brings about easy exchanges between pole and equator. One man on the footboard of the locomotive, one man shoveling into the furnaces the black powder that incloses the energy stored in early geological ages, a half dozen men mounted on the long train of following vehicles, combine to bring to the mill girl in Massachusetts, the miner in Pennsylvania, the sewing woman, and the wealthy merchant, her neighbor in New York, the flour made in Minnesota from the grain harvested a few weeks earlier in Dakota. All the world is served faithfully and efficiently by this unimaginable power, this product of the brain of the inventor, protected by the law, stimulated and aided by the capital that it has itself almost alone produced.
And thus have the inventors of the steam engine set in motion and placed at the disposal of mankind for every form of useful work all the great forces of nature; thus Hero of Alexandria touched the then concealed spring which called all the genii of earth, fire, water and air to do the bidding of the race. Thus Papin, Worcester, Newcomen, Watt, and Corliss and others of our own contemporaries, have applied the genii to their task of leveling mountains, traversing seas, continents, and the depths of the earth, building ships, locomotives, hamlets and cities, cottages and palaces, turning the spindle, operating the loom, and setting motion and giving energy to every machine, doing the work of thousands of millions of men, converting barbarism into civilization, giving necessaries of life in profusion, comforts in plenty, and luxuries in superabundance.
Aiding and working hand in hand with those other genii of progress, the inventors of the printing press and of the telegraph, the telephone, and the electric railway, of the modern system of textile manufactures, of iron and steel making, of the mowing machine and the harvester, they have compressed into two centuries the progress of a millennium, destitute of their aid. Every step taken under their stimulus, and with their help, is a step toward a higher life for all, intellectually and morally as well as physically; every advance in the improvement of their work is a gain to every man, woman, and child; every improvement of the steam engine is a help to the whole world. This progress makes the day of the extinction of the system now grinding the populations of the earth into the ground, the day of the abolition of armies and the restoration to the people of that freedom which characterized the times of the patriarchs, and of the restoration of the rights of the citizen to his own time and strength and producing power, perceptibly nearer.
When this final revolution shall have been accomplished, and when all the world has settled down to the steady and undisturbed work of production by daily and regular labor, aided by the genii of steam, of electricity, of all nature, combined for good, the results of the intellectual activity of the inventors of the steam engine will be fully seen. Then no monument will be required to keep green the memory of Watt, Corliss, or any other of these great men, but it will be said of them, as of Sir Christopher Wren in the epitaph in St. Paul's: "Seek you a monument, look about you!" Every wreath of steam rising to the heavens from factory, mill or workshop will be a reminder of Hero of Alexandria, every mine will possess a memorial to Papin, Worcester and Savery; every steamship will bring into grateful memory Fitch and Stevens, and Bell and Fulton; thousands of locomotives, crossing the continents, will perpetuate the thought of the Stephensons and their colleagues in the introduction of the railway; the hum of millions of spindles and the music of the electric wire will tell of the work of Corliss and his contemporaries and successors who made these things possible, and all kingdoms and races, all nations, will revere the name of James Watt, the genius to whom the world is most indebted for the beginnings of all this later and grander civilization which has converted the slow progress of earlier centuries into the meteor-like advance of to-day toward a future as grand and as mighty and as noble as humanity shall choose to make it. |
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