The genesis of the steam engine belongs to ancient history, for in the year 150 B. C. Hero made and exhibited in the Serapeum of Alexandria the first steam engine. It was of the rotary type and was known as the "aeolipile." During the middle ages the spirit of invention seems to have slept, for nearly eighteen centuries pa.s.sed from the time of Hero's engine before any active revival of interest was manifested in this field of invention. Giovanni Branca in 1629, the Marquis of Worcester in 1633, Dr. Papin in 1695, Savary in 1698, and Newcomen in 1705, were the pioneers of Watt, and gave to him a good working basis. Strange as it may appear, there was in 1894 and probably still is in existence in England an old Newcomen steam engine (see Fig. 76), which for at least a hundred years has stood exposed to the weather, slowly rusting and crumbling away. It is to be found in Fairbottom Valley, half way between Ashton-under-Lyne and Oldham, and is the property of the trustees of the late Earl of Stamford and Warrington. It is erected on a solid masonry pillar 14 by 7 feet at the base, which carries on its top, on trunnions, an oak beam 20 feet long and 12 by 14 inches thick. This beam is braced with iron, and has segmental ends with a piston at one end, and a balance weight at the other. The piston and pump rods are attached by chains. The cylinder is of cast iron, 27 inches in diameter, and about six foot stroke, the steam entering at the bottom only. It was formerly used for pumping a mine.

[Ill.u.s.tration: FIG. 76.--OLD NEWCOMEN ENGINE.]

The distinct and valuable legacy, however, which the Nineteenth Century received from the past, was the double acting steam engine of James Watt, disclosed in his British Pat. No. 1,321, of 1782. Prior to this date steam engines had been almost exclusively confined to raising water, but with the invention of Watt it extended into all fields of industrial use. Watt's double acting engine is shown in Fig. 77. It comprised a cylinder A, with double acting piston and valve gear E F G H; the parallel motion R for translating the reciprocating motion of the piston into the curved oscillatory path of the walking beam; a condenser chamber K, with spray I, for condensing the exhaust steam; a pump L J to remove the water from the condenser, and also the air, which is drawn out of the water by the vacuum; a water supply pump N; the automatic ball governor D, and throttle valve B. Two pins on the pump rod L strike the lever H and work the valve gear, and a collecting rod P and crank Q convert the oscillations of the walking beam into the continuous rotation of the fly wheel.

[Ill.u.s.tration: FIG. 77.--WATT'S DOUBLE ACTING STEAM ENGINE.]

Watt's automatic ball governor is shown in Fig. 78 and its function is as follows: When the working strain on an engine is relieved by the throwing out of action of a part of the work being performed, the engine would run too fast, or if more than a normal tax were placed on the engine, it would "slow up." To secure a regular and uniform motion in the performance of his engine Watt invented the automatic or self-regulating ball governor and throttle valve. A vertical shaft D is rotated constantly by a band on pulley _d_. Any tendency in the engine to run too fast throws the b.a.l.l.s up by centrifugal action, and this through toggle links _f h_, pulls down on a lever F G H, and partially closes the throttle valve Z, reducing the flow of steam to the engine.

When the engine has a tendency to run too slow the b.a.l.l.s drop down, and, deflecting the lever in the opposite direction, open the throttle valve, and increase the flow of steam to the engine. This double acting engine of Watt marks the beginning of the great epoch of steam engineering, and his patent expired just in time to give to the Nineteenth Century the greatest of all natal gifts.

[Ill.u.s.tration: FIG. 78.--WATT'S AUTOMATIC GOVERNOR AND THROTTLE VALVE.]

Steam engines are divided into two princ.i.p.al cla.s.ses, the low pressure engine, using steam usually under 40 pounds to the square inch, and the high pressure engine, using steam from 50 to 200 pounds. In the low pressure engine there is the expansive pressure of the steam on one side of the piston, aided by the suction of a vacuum on the opposite side of the piston, which vacuum is created by the condensation of the discharging, or exhaust steam, by cold water. As there are two factors at work impelling the piston, only a relatively low pressure in the boiler is required. In the high pressure engines there is no condensation of the exhaust steam, but it is discharged directly into the air, and this type was originally called "puffers." Familiar examples of the low pressure type are to be found in our side wheel pa.s.senger steamers, and of the high pressure type in the steam locomotive.

[Ill.u.s.tration: FIG. 79.--PRINCIPLE OF CUT-OFF.]

One of the most important steps in the development of the steam engine was the addition of the cut-off. Prior to its adoption steam was admitted to the cylinder during the whole time the piston was making its stroke from one end of the cylinder to the other. In the cut-off (see Fig. 79), when steam is being admitted through the port _p_, and the piston is being driven in the direction of the arrow, it was found that if the steam were cut off when the piston arrived at the position 1, the expansive action of the steam behind it in chamber _a_ would continue to carry the piston with an effective force to the end of its stroke, or to position 2. This of course effected a great saving in steam. Various cut-offs have been devised. Perhaps that most easily recognized by most persons is the one seen in the engine room of our side wheel steamers, of which ill.u.s.tration is given in Fig. 80. This was invented in 1841 by F. E. Sickels, and was the first successful drop cut-off. It was covered by his patents, May 20, 1842, July 20, 1843, October 19, 1844, No. 3,802, and September 19, 1845, No. 4,201. A rock shaft _s_ is worked by an eccentric rod _e_ from the paddle wheel shaft.

The rock shaft has lifting arms _a_ that act upon and alternately raise the feet _c_ on rods _b b_. One of these rods _b_ works the valves that admit steam, and the other the valves that discharge steam. The valve rod that admits steam has a quick drop, or fall, to cut off the live steam before the piston reaches the end of its stroke. In Fig. 81 is shown the celebrated Corliss cut-off and valve gear, in which a central wrist plate and four radiating rods work the valves. This valve gear was covered in Corliss patents, No. 6,162, March 10, 1849, and No. 8.253, July 29, 1851.

[Ill.u.s.tration: FIG. 80.--SICKELS' DROP CUT-OFF VALVE GEAR.]

[Ill.u.s.tration: FIG. 81.--CORLISS CUT-OFF AND VALVE GEAR.]

Among other important improvements in the steam engine are those for replenishing the water in the boiler, and the Giffard Injector is the simplest and most ingenious of all boiler feeds. It was invented in 1858 and covered by French patent No. 21,457, May 8, 1858, and U. S. patent No. 27,979, April 24, 1860. Prior to the Giffard Injector, steam boilers were supplied with water usually by steam pumps, which forced the water into the boiler against the pressure of the steam. The Giffard Injector takes a jet of steam from the boiler, and causes it to lift the water in an external pipe, and blow it directly into the boiler against its own pressure. So paradoxical and inoperative did this seem at first that it was met with incredulity, and not until repeated demonstrations established the fact was it accepted as an operative device. Its construction is shown in Fig. 82. A is a steam pipe communicating with the boiler, B another pipe receiving steam from A through small holes and terminating in a cone. C is a screw rod, cone-shaped at its extremity, turned by the crank M, and serving to regulate and even intercept the pa.s.sage of steam. D is a water suction pipe. The water that is drawn up introduces itself around the steam pipe and tends to make its exit through the annular s.p.a.ce at the conical extremity of the latter steam pipe. This annular s.p.a.ce is increased at will by means of the lever L, which acts upon a screw whose office is to cause the pipe B and its attached parts to move backward or forward. E is a diverging tube which receives the water injected by the jet of steam that condenses at I, and imparts to the water a portion of its speed in proportion to the pressure of the boiler. F is a box carrying a check valve to keep the water from issuing from the boiler when the apparatus is not at work. G is a pipe that leads the injected water to the boiler.

H is a purge or overflow pipe, K a sight hole which permits the operation of the apparatus to be watched, the stream of water being distinctly seen in the free interval. Fig. 83 shows the application of the injector to locomotives, which are now almost universally supplied with this device.

[Ill.u.s.tration: FIG. 82.--GIFFARD INJECTOR.]

[Ill.u.s.tration: FIG. 83.--INJECTOR ON LOCOMOTIVE.]

To keep the pressure in the boiler within the limit of safety, and adjusted to the work being performed, is an important part of the engineer's duty, and this he could not do without the steam gauge. One of the best known is the Bourdon gauge, shown in Fig. 84, constructed on the principle of the barometer invented by Bourdon of Paris in 1849 and patented in France June, 1849, and in the United States August 3, 1852, No. 9,163. A screw threaded thimble B, with stop c.o.c.k A, is screwed in the sh.e.l.l of the boiler, and a coiled pipe C communicates at one end with the thimble and is closed at the other end E and connected by a link F, with an arm on an axle, carrying an index hand that moves over a graduated scale. The coiled pipe C is in the nature of a flattened tube, as shown in the enlarged cross section, and is enclosed in a case.

When the steam pressure varies in this flat tube its coil expands or contracts, and in moving the index hand over the scale indicates the degree of pressure.

[Ill.u.s.tration: FIG. 84.--BOURDON'S PRESSURE GAUGE.]

In line with the development of the steam engine must be considered the efforts to economize fuel. These may be divided into the following cla.s.ses: Increased steam generating surface in boiler construction; surface condensers for exhaust steam; devices for promoting the combustion of fuel and burning the smoke, and feed water heaters. Even before the Nineteenth Century Smeaton devised the cylindrical boiler traversed by a flue, but the mult.i.tubular steam boiler of to-day represents a very important Nineteenth Century adjunct to the steam engine. Our locomotives, fire engines, and torpedo boat engines would be of no value without it. Sectional steam boilers made in detachable portions fastened together by packed or screw joints also represent an important development. These permit of the removal and replacement of any one section that may become defective, and are also capable of being built up section by section to any size needed. For promoting the combustion of fuel the draft is energized by blasts of air or steam, or both, either through hollow grate bars, jet pipes in the fire box, or by discharging the exhaust steam in the smoke pipe. Surface condensers pa.s.s the exhaust steam over the great surface area of a mult.i.tubular construction having cold water flowing through it. Feed water heaters utilize the waste heat escaping in the smoke flue to heat the water that is being fed to the boiler, so that it is warm when it is injected into the boiler, and the furnace is relieved of that much work.

[Ill.u.s.tration: FIG. 85.--BRANCA'S STEAM TURBINE, 1629.]

[Ill.u.s.tration: FIG. 86.--SECTION OF PARSONS TURBINE OF 1891.]

In the reciprocating type of steam engine the inertia of the piston must be overcome at the beginning of each stroke and its momentum must be arrested at the end of each stroke, and this involves a great loss of power. If the power of the steam could be applied so as to continuously move the piston in the same direction this loss would be avoided. The effort to do this has engaged the attention of many inventors, and the devices are called rotary engines. The most successful engines of this kind are those of the impact type, in which jets of steam impinge upon buckets after the manner of water on a water wheel, and which are known to-day as steam turbines. The earliest of these is Branca's steam turbine of 1629 (see Fig. 85) and the most important of this cla.s.s in use to-day are those of Mr. Parsons, of England, and De Laval, of Sweden. The internal construction of the Parsons turbine is seen in Fig.

86 and is covered by British patent No. 10,940, of 1891, and United States patent No. 553,658, January 28th, 1896. A series of turbines are set one after the other on the same axis, so that each takes steam from the preceding one, and pa.s.ses it on to the next. Each consists of a ring of fixed steam guides on the casing, and a ring of moving blades on the shaft. The steam pa.s.ses through the first set of guides, then through the first set of moving blades, then through the second set of guides, and then through the second set of moving blades, and so on.

[Ill.u.s.tration: FIG. 87.--PARSONS COMPOUND STEAM TURBINE, ON PLURALITY OF PROPELLER SHAFTS.]

In the application of his turbine to marine propulsion Mr. Parsons employs a plurality of propeller shafts and steam turbines, as seen in Fig. 87, and covered under United States patent No. 608,969, August 9, 1898.

[Ill.u.s.tration: FIG. 88.--DE LAVAL'S STEAM TURBINE.]

[Ill.u.s.tration: FIG. 89.--DE LAVAL TURBINE GEARED TO DYNAMO.]

The De Laval turbine, as shown in Fig. 88, is of very simple construction, consisting only of a steel wheel with a series of buckets at its periphery enclosed by a circular rim, and a series of steam nozzles on the side with diverging jet orifices directing steam jets against the buckets. A speed of 30,000 revolutions a minute may be attained by this construction. In Fig. 89 is shown a 300 horse-power steam turbine of the De Laval type applied to a dynamo; to which this type of engine is peculiarly adapted. The dynamo is seen on the extreme right, the steam turbine on the extreme left, and the drum-shaped casing between contains cog-gearing by which the high revolution of the turbine wheel is reduced to a proper working speed for the dynamo.

Within the last few years application of the Parsons steam turbine has been made to marine propulsion with very remarkable results as to speed.

The small steam craft, "The Turbinia," built in 1897, and supplied with three of Parsons' compound steam turbines, developed a speed of 32 knots, and more recently the torpedo boat "Viper" has with steam turbines attained the remarkable speed of 37.1 knots, or over 40 statute miles an hour. About 2,000 United States patents have been granted on various forms of rotary engines.

In the transportation building of the World's Fair at Chicago in 1893 one of the most conspicuous objects of attention was the model of the great Bethlehem Iron Co.'s steam hammer, standing with its feet apart like some great "Colossus of Rhodes" and towering 91 feet high among the models of the great ocean steamers and battleships which are so largely dependent upon the work of this t.i.tanic machine. Its hammer head, in the working-machine, weighs 125 tons, and many of the seventeen inch thick armor plates for our battleships have been forged by its tremendous blows.

In 1838, during the construction of the "Great Britain," the largest steamship up to that time ever built, it was found that there was not a forge hammer in England or Scotland powerful enough to forge a paddle shaft for that vessel. The emergency was met by Mr. Nasmyth, of England, who invented the steam hammer and covered it in British patent No.

9,382, of 1842 (U. S. Pat. No. 3,042, April 10, 1843). A modern example of it is seen in Fig. 90. It consists of a steam cylinder at the top whose piston is attached to a block of iron, forming the hammer head and sliding vertically in guides between the two legs of the frame. Valve gear is arranged to control the flow of steam to and from the opposite sides of the piston, and so nicely adjusted is the valve gear of such a modern steam hammer that it is said that an expert workman can manipulate the great ma.s.s of metal with such accuracy and delicacy as to crack an egg in a winegla.s.s without touching the gla.s.s. To the steam hammer we owe the first heavy armor plate for our battle ships and the propeller shafts of our earlier steamships. In fact it was the steam hammer which first rendered the large steamship possible. Mr. Nasmyth not only invented the steam hammer, but the steam pile driver as well.

[Ill.u.s.tration: FIG. 90.--STEAM HAMMER.]

For quick action, nicely adjusted machinery, and showy finish the steam fire engine is a familiar and conspicuous application of steam power. A dude among engines when on dress parade, and a sprinter when on the run, it gets to work with the vim and efficiency of a thoroughbred, and is a most business-like and valuable custodian of life and property. The first portable steam fire engine was built about 1830 by Mr. Brathwaite and Capt. Ericsson in London. In 1841 Mr. Hodges produced a similar engine in New York City. Cincinnati was the first city to adopt the steamer as a part of its fire department apparatus. To-day all the important cities and towns of the civilized world rely upon the steam fire engines for their longevity and existence. Time economy in getting into action is the great objective point of most improvements of the fire-engine, and one of the most important is the keeping of the water in the boiler hot when the engine is out of action at the engine house, so that when the fire is built and the run is made to the scene of action, the water will be hot to start with. This attachment was the invention of William A. Brickill, and was patented by him August 18, 1868, No. 81,132. In the ill.u.s.tration, Fig. 91, the two pipes pa.s.sing from the engine through the trap door in the floor connect with a water heater in the bas.e.m.e.nt below, which heater maintains a constant circulation of hot water in the steam boiler. Couplings in these pipes serve to quickly disconnect the engine when the run to the fire is to be made.

[Ill.u.s.tration: FIG. 91.--STEAM FIRE ENGINE WITH WATER HEATING ATTACHMENT.]

Among other useful applications of the steam engine are the steam plow, steam drill, steam dredge, steam press, and steam pump, of which latter the Blake, Knowles, and Worthington are representative types.

[Ill.u.s.tration: FIG. 92.--THE SIX-CYLINDER QUADRUPLE EXPANSION ENGINES OF THE "DEUTSCHLAND," 35,640 HORSE POWER.]

The highest type of modern steam engines is to be found in the compound multiple-expansion engine, in which three or more cylinders of different diameters with corresponding pistons are so arranged that steam is made to act first upon the piston in the smallest cylinder at high pressure, and then discharging into the next larger cylinder, called the intermediate, acts expansively upon its piston, and thence, pa.s.sing into the still larger low pressure cylinder, imparts its further expansive effect upon its piston. The fundamental principle of the compound engine dates back to the time of Watt, its first embodiment appearing in the Hornblower compound engine, as described in British patent No. 1,298, of 1781, but modern improvements have differentiated it into almost a new invention. A fine example is shown in Fig. 92, which represents the quadruple expansion engines of the "Deutschland," the new steamer of the Hamburg-American Line. The two high pressure cylinders, however, do not appear in the ill.u.s.tration, being too high for the shops. They stand vertically, however, upon the two bed plates which appear at the top of the two low pressure cylinders. In each set of six cylinders the two low pressure cylinders are in the middle, the two high pressure cylinders immediately above them or arranged tandem, while at the forward end is the first intermediate cylinder, and at the after end is the second intermediate. The low pressure cylinders are 106 inches in diameter, the intermediate cylinders are 73.6 inches and 103.9 inches respectively, and the two high pressure cylinders are 30.6 inches, and the steam pressure is 225 pounds. Its improvements comprehend the systems of Schlick, patented in the United States November 23, 1897, No. 594,288 and 594,289, and Taylor, patented November 22, 1898, No. 614,674, which embody fine mathematical principles for balancing the momentum of the great ma.s.ses of moving parts, so that the engine may run up to high speed without vibrations and damaging strains upon the hull.

Mulhall gives the steam horse power of the world in 1895, not including war vessels, as follows:

Stationary. Railway. Steamboat. Total.

The World 11,340,000 32,235,000 12,005,000 55,580,000 United States 3,940,000 10,800,000 2,200,000 16,940,000

The increase in steam power in the United States has been from 3,500,000 horse power in 1860, to 16,940,000 horse power in 1895, or about five fold within thirty-five years.

Prof. Thurston says that in 1890 the combined power of all the steam engines of the world was not far from 100,000,000[2] horse power, of which the United States had 15,000,000, Great Britain the same, and the other countries smaller amounts. Taking the horse power as the equivalent of the work of five men, the work of steam is equivalent to that of a population of 500,000,000 working men. It is also said that one man to-day, with the aid of a steam engine, performs the work of 120 men in the last century.

[2] Prof. Thurston's estimate doubtless includes war vessels, which Mulhall's later estimate does not (see Mulhall's "Industries and Wealth of Nations," 1896, pages 4 and 379).

The influence of the steam engine upon the history and destiny of the world is an impressive subject, far beyond any intelligent computation or estimate. It has been the greatest moving force of the Nineteenth Century. The labor of 100,000 men for twenty years might build a great pyramid in Egypt, and it remains as a monument of patience only, but the genius of the modern inventor has organized a machine with muscles of steel, far more patient and tireless than those of the Egyptian slave.

He gave it but a drink of water and making coal its black slave, and himself the master of both, he has in the Nineteenth Century hitched his chariot to a star and driven to unparalleled achievement.

CHAPTER XI.

THE STEAM RAILWAY.

TREVITHICK'S FIRST LOCOMOTIVE--BLENKINSOP'S LOCOMOTIVE--HEDLEY'S "PUFFING BILLY"--STEPHENSON'S LOCOMOTIVE--THE LINK MOTION--STOCKTON AND DARLINGTON RAILWAY, 1825--HACKWORTH'S "ROYAL GEORGE"-- "STOURBRIDGE LION"--"JOHN BULL"--BALDWIN'S LOCOMOTIVES--WESTINGHOUSE AIR BRAKES--JANNEY CAR COUPLING--THE WOODRUFF SLEEPING CAR--RAILWAY STATISTICS.

The fact that more patents have been granted in the cla.s.s of carriages and wagons than in any other field, shows that means of transportation has engaged the largest share of man's inventive genius, and has been most closely allied to his necessities. The moving of pa.s.sengers and freight seems to be directly related to the progress of civilization, and the factor whose influence has been most felt in this field is the steam locomotive. Sir Isaac Newton in 1680 proposed a steam carriage propelled by the reaction of a jet of steam. Dr. Robinson in 1759 suggested the steam carriage to Watt. Cugnot in 1769 built a steam carriage. Symington, in 1770, and Murdock, in 1784, built working models, and in 1790 Nathan Read also made experiments in steam transportation, but the Nineteenth Century dawned without any other results than a few abandoned experiments, and the criticism and disappointment of the inventors in this field.