Engineers and their triumphs (eBook)
114 Seiten
Good Press (Verlag)
978-4-06-643737-6 (ISBN)
CHAPTER II.
GLANCING BACKWARDS AND STRUGGLING FORWARDS.
“My lord, will you spend the money to build a Travelling Engine?”
“Why? what would it do?”
“Haul coals to the Tyne, my lord. The present system of hauling by horses is very costly.”
“It is. But how would you manage it by a Travelling Engine?” Thereupon George Stephenson the engine-wright proceeded to explain.
In some such manner as this we can imagine that Stephenson opened up the subject to Lord Ravensworth, the chief partner in the Killingworth Colliery; and he won his lordship over.
Stephenson had already improved the colliery engines, and Lord Ravensworth had formed a high opinion of his abilities. So after consideration he gave the required consent.
Now, let us endeavour to imagine the position. The steam engine, of which the locomotive is one form, had been invented years before. The Marquis of Worcester made something of a steam engine which apparently was working at Vauxhall, South-west London, in 1656. It is said that he raised water forty feet, and by this we may infer that his apparatus was a steam-pump. He describes it in his work “Century of Inventions,” about 1655, and he is generally accredited with being the inventor of the steam engine. It was, however, a very primitive affair, the boiler being the same vessel as that in which the steam accomplished its work.
Captain Savery took the next step. He was the first to obtain a patent for applying steam power to machinery. This was in 1698, and he used a boiler distinct from the vessel where the steam was to exert its power. Savery’s engines appear to have been used to drain mines.
His engines acted in this way—the steam was condensed in a vessel and produced a vacuum which raised the water; then the steam pressing upon it raised it further in another receptacle.
An obvious improvement was the introduction of the piston. This was Papin’s idea, and he used it first in 1690. Six years later an engine was constructed by Savery, Newcomen (a Devonshire man), and Cawley, in which the “beam” was introduced, and also the ideas of a distinct boiler separate from a cylinder in which worked a piston. This machine was in operation for about seventy years. The beam worked on an axle in its centre—something like a child’s “see-saw,” and one end being attached to the piston moving in the cylinder, it was worked up and down, the other end of the beam being fastened to the pump-rod, which was thus alternately raised and depressed.
The upward movement of the piston having been effected by a rush of steam from the boiler upon its head, the steam was cut off and cold water run in upon it from a cistern. The steam was thus condensed by the water and a vacuum caused, and the piston was pressed down by the weight of the atmosphere—of course dragging down its end of the beam, and raising the pump-rod. The steam was then turned on again and pushed up the piston, and consequently the end of the beam also. Thus the engine continued to work, the turning of the cocks to admit steam and water being performed by an attendant. The engine was, however, made self-acting in this respect, and Smeaton improved this form of engine greatly. The beam is still used in engines for pumping.
Nevertheless, improved though it became, it was still clumsy and almost impracticable. It was the genius of James Watt which changed it from a slow, awkward, cumbrous affair into a most powerful, practicable, and useful machine.
His great improvements briefly were these: he condensed the steam in a separate vessel from the cylinder, and thus avoided cooling it and the consequent loss of steam power; secondly, he used the steam to push back the piston as well as to push it forward (this is called the “double-acting engine,” and is now always used); thirdly, he introduced the principle of using the steam expansively, causing economy in working; and fourthly, he enabled a change to be made of the up and down motion of the piston into a circular motion by the introduction of the crank.
JAMES WATT.
The use of the steam expansively is to stop its rush to the cylinder when the piston has only partially accomplished its stroke, leaving the remainder of the stroke to be driven by the expansion of the steam. In early engines the steam was admitted by conical valves, worked by a rod from the beam. Murdock, we may add in parenthesis, is believed to have invented the slide-valve which came into use as locomotives were introduced, and of which there are now numerous forms. The valve is usually worked by an “eccentric” rod on the shaft of the engine.
Watt was the author of many other inventions and improvements of the steam engine. Indeed, although Savery and Newcomen and others are entitled to great praise, it was Watt who gave it life, so to speak, and made it, in principle and essence, very much that which we now possess. There have, indeed, been improvements as to the boiler, as to expansive working, and in various details, since his day; but, apart from the distinctive forms of the locomotive and the marine engine, the machine as a whole is in principle much as Watt left it.
The centre of all things in a steam engine is usually the cylinder. Here the piston is moved backward and forward, and thence gives motion as required to other parts of the machine.
The cylinder is in fact an air-tight, round box, fitted with a close-fitting, round plate of metal, to which is fixed the piston-rod. Now, it must be obvious that if the steam be admitted at one end of the cylinder it will, as it rushes in, push the metal plate and the piston outward, and if this steam be cut off, and the steam admitted to the other end of the cylinder, it will push the metal plate and piston back again.
But what is to be done with the steam after it has accomplished its work? It may be permitted to spurt out into the air, or into a separate vessel, where it may be condensed. In the locomotive, under Stephenson’s able handling, this escape of steam was created into a steam-blast in the chimney to stimulate the fire. In compound and triple-expansion engines the steam is used—or expanded, it is called—in two or three cylinders respectively. When steam is condensed, it may be returned to the boiler as water.
It was the repairing of a Newcomen engine that seems to have started Watt on his inventions and improvements of the steam engine. He was then a mathematical instrument maker at Glasgow. As a boy he had suffered from poor health, but had been very observant and studious; and it is said that his aunt chided him on one occasion for wasting time in playing with her tea-kettle. He would watch the steam jetting from its spout, and would count the water-drops into which the steam would condense when he held a cup over the white cloud.
Delicate though he was in health, he studied much, and came, indeed, to make many other articles besides mathematical instruments. When, therefore, the Newcomen engine needed repair, it was not unnatural that it should be brought to him. It appears to have been a working model used at Glasgow University. He soon repaired the machine; but, in examining it, he became possessed with the idea that it was very defective, and he pondered long over the problem—How it might be improved. What was wanting in it? How could the steam be condensed without cooling the cylinder?
Suddenly, one day, so the story goes, the idea struck him, when loitering across the common with bent brows, that if steam were elastic, it would spurt into any vessel empty of air. Impatiently, he hastened home to try the experiment. He connected the cylinder of an engine with a separate vessel, in which the air was exhausted, and found that his idea was correct; the steam did rush into it. Consequently the steam could be condensed in a separate vessel, and the heat of the cylinder maintained and the loss of power prevented. This invention seems simple enough; yet it increased the power of an engine threefold, and is at the root of Watt’s fame. We must remember that the inventions which in process of time may appear the simplest and the most commonplace, may be the most difficult to originate. And it may fairly be urged—If it were so very simple, and so very obvious, why was it not invented before? The supposition is that in those days it was not so simple. It is possible that the great elasticity of steam was not sufficiently understood. In any case, the discovery and its application are regarded as his greatest invention.
Yet ten years elapsed before he constructed a real working steam engine, and so great we may suppose were the difficulties he encountered, including poorness of health, that once he is reported to have exclaimed: “Of all things in the world, there is nothing so foolish as inventing.”
But a brilliant triumph succeeded. Eventually Watt became partner with Mr. Matthew Boulton, and the firm of Boulton & Watt manufactured the engine at Soho Ironworks, Birmingham. Mining proprietors soon discovered the value of the new machine, and Newcomen’s engine was superseded for pumping.
Watt continued to improve the machine, and together with Boulton also greatly improved the workmanship of constructing engines and machinery. In a patent taken out in 1784, he “described a steam locomotive”; but for some reason he did not prosecute the idea. It is possible that the notion of building a special road for it to run upon did not occur to him, or appear very practicable.
His work was done, and it was a great work; but it was left for others to develop the steam engine into forms for hauling carriages on land or propelling ships upon the sea. Trevithick, Stephenson,...
| Erscheint lt. Verlag | 10.7.2023 |
|---|---|
| Sprache | englisch |
| Themenwelt | Technik ► Bauwesen |
| ISBN-10 | 4-06-643737-0 / 4066437370 |
| ISBN-13 | 978-4-06-643737-6 / 9784066437376 |
| Haben Sie eine Frage zum Produkt? |
EPUB (Wasserzeichen)Größe: 2,6 MB
DRM: Digitales Wasserzeichen
Dieses eBook enthält ein digitales Wasserzeichen und ist damit für Sie personalisiert. Bei einer missbräuchlichen Weitergabe des eBooks an Dritte ist eine Rückverfolgung an die Quelle möglich.
Dateiformat: EPUB (Electronic Publication)
EPUB ist ein offener Standard für eBooks und eignet sich besonders zur Darstellung von Belletristik und Sachbüchern. Der Fließtext wird dynamisch an die Display- und Schriftgröße angepasst. Auch für mobile Lesegeräte ist EPUB daher gut geeignet.
Systemvoraussetzungen:
PC/Mac: Mit einem PC oder Mac können Sie dieses eBook lesen. Sie benötigen dafür die kostenlose Software Adobe Digital Editions.
eReader: Dieses eBook kann mit (fast) allen eBook-Readern gelesen werden. Mit dem amazon-Kindle ist es aber nicht kompatibel.
Smartphone/Tablet: Egal ob Apple oder Android, dieses eBook können Sie lesen. Sie benötigen dafür eine kostenlose App.
Geräteliste und zusätzliche Hinweise
Buying eBooks from abroad
For tax law reasons we can sell eBooks just within Germany and Switzerland. Regrettably we cannot fulfill eBook-orders from other countries.
aus dem Bereich
