[Ill.u.s.tration: FIG. 88.--Bull"s Pumping-Engine, 1798.]
The steam-cylinder, _a_, is carried on wooden beams, _b_, extending across the engine-house directly over the pump-well. The piston-rod, _c_, is secured to the pump-rods, _d d_, the cylinder being inverted, and the pumps, _e_, in the shaft, _f_, are thus operated without the intervention of the beam invariably seen in Watt"s engines. A connecting-rod, _g_, attached to the pump-rod and to the end of a balance-beam, _h_, operates the latter, and is counterbalanced by a weight, _i_. The rod, _j_, serves both as a plug-rod and as an air-pump connecting-rod. A snifting-valve, _k_, opens when the engine is blown through, and relieves the condenser and air-pump, _l_, of all air. The rod, _m_, operates a solid air-pump piston, the valves of the pump being placed on either side at the base, instead of in the pump-bucket, as in Watt"s engines. The condensing-water cistern was a wooden tank, _n_. A jet "pipe-condenser," _o_, was used instead of a jet condenser of the form adopted by other makers, and was supplied with water through the c.o.c.k, _p_. The plug-rod, _q_, as it rises and falls with the pump-rods and balance-beam, operates the "gear-handles," _r r_, and opens and closes the valves, _s s_, at the required points in the stroke. The attendant works these valves by hand, in starting, from the floor, _t_. The operation of the engine is similar to that of a Watt engine. It is still in use, with a few modifications and improvements, and is a very economical and durable machine. It has not been as generally adopted, however, as it would probably have been had not the legal proscription of Watt"s patents so seriously interfered with its introduction. Its simplicity and lightness are decided advantages, and its designers are ent.i.tled to great credit for their boldness and ingenuity, as displayed in their application of the minor devices which distinguish the engine. The design is probably to be credited to Bull originally; but Trevithick built some of these engines, and is supposed to have greatly improved them while working with Edward Bull, the son of the inventor, William Bull. One of these engines was erected by them at the Herland Mine, Cornwall, in 1798, which had a steam-cylinder 60 inches in diameter, and was built on the plan just described.
Another of the contemporaries of James Watt was a clergyman, EDWARD CARTWRIGHT, the distinguished inventor of the power-loom, and of the first machine ever used in combing wool, who revived Watt"s plan of surface-condensation in a somewhat modified form. Watt had made a "pipe-condenser," similar in plan to those now often used, but had simply immersed it in a tank of water, instead of in a constantly-flowing stream. Cartwright proposed to use two concentric cylinders or spheres, between which the steam entered when exhausted from the cylinder of the engine, and was condensed by contact with the metal surfaces. Cold water within the smaller and surrounding the exterior vessel kept the metal cold, and absorbed the heat discharged by the condensing vapor.
Cartwright"s engine is best described in the _Philosophical Magazine_ of June, 1798, from which the accompanying sketch is copied.
[Ill.u.s.tration: FIG. 39.--Cartwright"s Engine, 1798.]
The object of the inventor is stated to have been to remedy the defects of the Watt engine--imperfect vacuum, friction, and complication.
In the figure, the steam-cylinder takes steam through the pipe, _B_.
The piston, _R_, has a rod extending downward to the smaller pump-piston, _G_, and upward to the cross-head, which, in turn, drives the cranks above, by means of connecting-rods. The shafts thus turned are connected by a pair of gears, _M L_, of which one drives a pinion on the shaft of the fly-wheel. _D_ is the exhaust-pipe leading to the condenser, _F_; and the pump, _G_, removes the air and water of condensation, forcing it into the hot-well, _H_, whence it is returned to the boiler through the pipe, _I_. A float in _H_ adjusts an air-valve, so as to keep a supply of air in the chamber, to serve as a cushion and to make an air-chamber of the reservoir, and permits the excess to escape. The large tank contains the water supplied for condensing the steam.
The piston, _R_, is made of metal, and is packed with two sets of cut metal rings, forced out against the sides of the cylinder by steel springs, the rings being cut at three points in the circ.u.mference, and kept in place by the springs. The arrangement of the two cranks, with their shafts and gears, is intended to supersede Watt"s plan for securing a perfectly rectilinear movement of the head of the piston-rod, without friction.
In the accounts given of this engine, great stress is laid upon the supposed important advantage here offered, by the introduction of the surface-condenser, of permitting the employment of a working-fluid other than steam--as, for example, alcohol, which is too valuable to be lost. It was proposed to use the engine in connection with a still, and thus to effect great economy by making the fuel do double duty.
The only part of the plan which proved both novel and valuable was the metallic packing and piston, which has not yet been superseded. The engine itself never came into use.
At this point, the history of the steam-engine becomes the story of its applications in several different directions, the most important of which are the raising of water--which had hitherto been its only application--the locomotive-engine, the driving of mill-machinery, and steam-navigation.
Here we take leave of James Watt and of his contemporaries, of the former of whom a French author[43] says: "The part which he played in the mechanical applications of the power of steam can only be compared to that of Newton in astronomy and of Shakespeare in poetry." Since the time of Watt, improvements have been made princ.i.p.ally in matters of mere detail, and in the extension of the range of application of the steam-engine.
[43] Bataille. "Traite des Machines a Vapeur," Paris, 1847.
[Ill.u.s.tration]
CHAPTER IV.
_THE MODERN STEAM-ENGINE._
"Those projects which abridge distance have done most for the civilization and happiness of our species."--MACAULAY.
THE SECOND PERIOD OF APPLICATION--1800-"40.
STEAM-LOCOMOTION ON RAILROADS.
[Ill.u.s.tration: FIG. 40.--The First Railroad-Car, 1825.]
Introductory.--The commencement of the nineteenth century found the modern steam-engine fully developed in all its princ.i.p.al features, and fairly at work in many departments of industry. The genius of Worcester, and Morland, and Savery, and Desaguliers, had, in the first period of the application of the power of steam to useful work, effected a beginning which, looked upon from a point of view which exhibits its importance as the first step toward the wonderful results to-day familiar to every one, appears in its true light, and ent.i.tles those great men to even greater honor than has been accorded them. The results actually accomplished, however, were absolutely insignificant in comparison with those which marked the period of development just described. Yet even the work of Watt and of his contemporaries was but a mere prelude to the marvellous advances made in the succeeding period, to which we are now come, and, in extent and importance, was insignificant in comparison with that accomplished by their successors in the development of all mechanical industries by the application of the steam-engine to the movement of every kind of machine.
The first of the two periods of application saw the steam-engine adapted simply to the elevation of water and the drainage of mines; during the second period it was adapted to every variety of useful work, and introduced wherever the muscular strength of men and animals, or the power of wind and of falling water, which had previously been the only motors, had found application. A history of the development of industries by the introduction of steam-power during this period, would be no less extended and hardly less interesting than that of the steam-engine itself.
The way had been fairly opened by Boulton and Watt; and the year 1800 saw a crowd of engineers and manufacturers entering upon it, eager to reap the harvest of distinction and of pecuniary returns which seemed so promising to all. The last year of the eighteenth century was also the last of the twenty-five years of partnership of Boulton & Watt, and, with it, the patents under which that firm had held the great monopoly of steam-engine building expired. The right to manufacture the modern steam-engine was common to all. Watt had, at the commencement of the new century, retired from active business-life.
Boulton remained in business; but he was not the inventor of the new engine, and could not retain, by the exercise of all his remaining power, the privileges previously held by legal authorization.
The young Boulton and the young Watt were not the Boulton & Watt of earlier years; and, had they possessed all of the business talent and all of the inventive genius of their fathers, they could not have retained control of a business which was now growing far more rapidly than the facilities for manufacturing could be extended in any single establishment. All over the country, and even on the Continent of Europe, and in America, thousands of mechanics, and many men of mechanical tastes in other professions, were familiar with the principles of the new machine, and were speculating upon its value for all the purposes to which it has since been applied; and a mult.i.tude of enthusiastic mechanics, and a larger mult.i.tude of visionary and ignorant schemers, were experimenting with every imaginable device, in the vain hope of attaining perpetual motion, and other hardly less absurd results, by its modification and improvement. Steam-engine building establishments sprang up wherever a mechanic had succeeded in erecting a workshop and in acquiring a local reputation as a worker in metal, and many of Watt"s workmen went out from Soho to take charge of the work done in these shops. Nearly all of the great establishments which are to-day most noted for their extent and for the importance and magnitude of the work done in them, not only in Great Britain, but in Europe and the United States, came into existence during this second period of the application of the steam-engine as a prime mover.
The new establishments usually grew out of older shops of a less pretentious character, and were managed by men who had been trained by Watt, or who had had a still more awakening experience with those who vainly strove to make up, by their ingenuity and by great excellence of workmanship, the advantages possessed at Soho in a legal monopoly and greater experience in the business.
It was exceedingly difficult to find expert and conscientious workmen, and machine-tools had not become as thoroughly perfected as had the steam-engine itself. These difficulties were gradually overcome, however, and thenceforward the growth of the business was increasingly rapid.
Every important form of engine had now been invented. Watt had perfected, with the aid of Murdoch, both the pumping-engine and the rotative steam-engine for application to mills. He had invented the trunk engine, and Murdoch had devised the oscillating engine and the ordinary slide-valve, and had made a model locomotive-engine, while Hornblower had introduced the compound engine. The application of steam to navigation had been often proposed, and had sometimes been attempted, with sufficient success to indicate to the intelligent observer an ultimate triumph. It only remained to extend the use of steam as a motor into all known departments of industry, and to effect such improvements in details as experience should prove desirable.
The engines of Hero, of Porta, and of Branca were, it will be remembered, non-condensing; but the first plan of a non-condensing engine that could be made of any really practical use is given in the "Theatrum Machinarum" of Leupold, published in 1720. This sketch is copied in Fig. 41. It is stated by Leupold that this plan was suggested by Papin. It consists of two single-acting cylinders, _r s_, receiving steam alternately from the same steam-pipe through a "four-way c.o.c.k," _x_, and exhausting into the atmosphere. Steam is furnished by the boiler, _a_, and the pistons, _c d_, are alternately raised and depressed, depressing and raising the pump-rods, _k l_, to which they are attached by the beams, _h g_, vibrating on the centres, _i i_. The water from the pumps, _o p_, is forced up the stand-pipe, _q_, and discharged at its top. The alternate action of the steam-pistons is secured by turning the "four-way c.o.c.k," _x_, first into the position shown, and then, at the completion of the stroke, into the reverse position, by which change the steam from the boiler is then led into the cylinder, _s_, and the steam in _r_ is discharged into the atmosphere.[44]
[44] _Vide_ "Theatrum Machinarum," vol. iii., Tab. 30.
[Ill.u.s.tration: FIG. 41.--Leupold"s Engine, 1720.]
Leupold states that he is indebted to Papin for the suggestion of the peculiar valve here used. He also proposed to use a Savery engine without condensation in raising water. We have no evidence that this engine was ever built.
The first rude scheme for applying steam to locomotion on land was probably that of Isaac Newton, who, in 1680, proposed the machine shown in the accompanying figure (42), which will be recognized as representing the scientific toy which is found in nearly every collection of ill.u.s.trative philosophical apparatus. As described in the "Explanation of the Newtonian Philosophy," it consists of a spherical boiler, _B_, mounted on a carriage. Steam issuing from the pipe, _C_, seen pointing directly backward, by its reaction upon the carriage, drives the latter ahead. The driver, sitting at _A_, controls the steam by the handle, _E_, and c.o.c.k, _F_. The fire is seen at _D_.
[Ill.u.s.tration: FIG. 42.--Newton"s Steam-Carriage, 1680.]
When, at the end of the eighteenth century, the steam-engine had been so far perfected that the possibility of its successful application to locomotion had become fully and very generally recognized, the problem of adapting it to locomotion on land was attacked by many inventors.
Dr. Robison had, as far back as in 1759, proposed it to James Watt during one of their conferences, at a time when the latter was even more ignorant than the former of the principles which were involved in the construction of the steam-engine, and this suggestion may have had some influence in determining Watt to pursue his research; thus setting in operation that train of thoughtful investigation and experiment which finally earned for him his splendid fame.
In 1765, that singular genius, Dr. Erasmus Darwin, whose celebrity was acquired by speculations in poetry and philosophy as well as in medicine, urged Matthew Boulton--subsequently Watt"s partner, and just then corresponding with our own Franklin in relation to the use of steam-power--to construct a steam-carriage, or "fiery chariot," as he poetically styled it, and of which he sketched a set of plans. A young man named Edgeworth became interested in the scheme, and, in 1768, published a paper which had secured for him a gold medal from the Society of Arts. In this paper he proposed railroads on which the carriages were to be drawn by horses, _or by ropes from steam-winding engines_.
[Ill.u.s.tration: FIG. 43.--Read"s Steam-Carriage, 1790.]
Nathan Read, of whom an account will be given hereafter, when describing his attempt to introduce steam-navigation, planned, and in 1790 obtained a patent for, a steam-carriage, of which the sketch seen in Fig. 43 is copied from the rough drawing accompanying his application. In the figure, _A A A A_ are the wheels; _B B_, pinions on the hubs of the rear wheels, which are driven by a ratchet arrangement on the racks, _G G_, connected with the piston-rods; _C o_ is the boiler; _D D_, the steam-pipes carrying steam to the steam-cylinder, _E E_; _F F_ are the engine-frames; _H_ is the "tongue" or "pole" of the carriage, and is turned by a horizontal steering-wheel, with which it is connected by the ropes or chains, _I K_, _I K_; _W W_ are the c.o.c.ks, which serve to shut off steam from the engine when necessary, and to determine the amount of steam to be admitted. The pipes _a a_ are exhaust-pipes, which the inventor proposed to turn so that they should point backward, in order to secure the advantage of the effort of reaction of the expelled steam.
Read made a model steam-carriage, which he exhibited when endeavoring to secure a.s.sistance in furtherance of his schemes, but seems to have given more attention to steam-navigation, and nothing was ever accomplished by him in this direction.
These were merely promising schemes, however. The first actual experiment was made, as is supposed, by a French army-officer, NICHOLAS JOSEPH CUGNOT, who in 1769 built a steam-carriage, which was set at work in presence of the French Minister of War, the Duke de Choiseul. The funds required by him were furnished by the Compte de Saxe. Encouraged by the partial success of the first locomotive, he, in 1770, constructed a second (Fig. 44), which is still preserved in the Conservatoire des Arts et Metiers, Paris.
[Ill.u.s.tration: FIG. 44.--Cugnot"s Steam-Carriage, 1770.]
This machine, when recently examined by the author, was still in an excellent state of preservation. The carriage and its machinery are substantially built and well-finished, and exceedingly creditable pieces of work in every respect. It surprises the engineer to find such evidence of the high character of the work of the mechanic Brezin a century ago. The steam-cylinders were 13 inches in diameter, and the engine was evidently of considerable power. This locomotive was intended for the transportation of artillery. It consists of two beams of heavy timber extending from end to end, supported by two strong wheels behind, and one still heavier but smaller wheel in front. The latter carries on its rim blocks which cut into the soil as the wheel turns, and thus give greater holding power. The single wheel is turned by two single-acting engines, one on each side, supplied with steam by a boiler (seen in the sketch) suspended in front of the machine. The connection between the engines and the wheels was effected by means of pawls, as first proposed by Papin, which could be reversed when it was desired to drive the machine backward. A seat is mounted on the carriage-body for the driver, who steers the machine by a train of gearing, which turns the whole frame, carrying the machinery 15 or 20 degrees either way. This locomotive was found to have been built on a tolerably satisfactory general plan; but the boiler was too small, and the steering apparatus was incapable of handling the carriage with promptness.
The death of one of Cugnot"s patrons, and the exile of the other, put an end to Cugnot"s experiments.
Cugnot was a mechanic by choice, and exhibited great talent. He was a native of Vaud, in Lorraine, where he was born in 1725. He served both in the French and the German armies. While under the Marechal de Saxe, he constructed his first steam locomotive-engine, which only disappointed him, as he stated, in consequence of the inefficiency of the feed-pumps. The second was that built under the authority of the Minister Choiseul, and cost 20,000 livres. Cugnot received from the French Government a pension of 600 livres. He died in 1804, at the age of seventy-nine years.
Watt, at a very early period, proposed to apply his own engine to locomotion, and contemplated using either a non-condensing engine or an air-surface condenser. He actually included the locomotive-engine in his patent of 1784; and his a.s.sistant, Murdoch, in the same year, made a working-model locomotive (Fig. 45), which was capable of running at a rapid rate. This model, now deposited in the Patent Museum at South Kensington, London, had a flue-boiler, and its steam-cylinder was three-fourths of an inch in diameter, and the stroke of piston 2 inches. The driving-wheels were 9-1/2 inches diameter.
[Ill.u.s.tration: FIG. 45.--Murdoch"s Model, 1784.]
Nothing was, however, done on a larger scale by either Watt or Murdoch, who both found more than enough to claim their attention in the construction and introduction of other engines. Murdoch"s model is said to have run from 6 to 8 miles an hour, its little driving-wheels making from 200 to 275 revolutions per minute. As is seen in the sketch, this model was fitted with the same form of engine, known as the "gra.s.shopper-engine," which was used in the United States by Oliver Evans.