Difference Engine

“ During the time the engine is under steam with a train, everything seen, heard, felt and smelt is capable of affording a lesson.
On the engine the eye is trained to distinguish different colors at considerable distances. If one is color-blind he cannot be a good engineer.
On the engine the ear learns to detect the slightest variation in the beats and knocks about the machinery—to distinguish the difference between the knock of an axle box and the knock of a journal. ”

“ Such gains in efficiency, which give constructors more latitude in the placing of weight and strength where experience show they are needed, have gone far to produce an airworthy machine. In the old days, when machines were inefficient, a few revolutions more or less per minute in the running of an engine meant all the77 difference between an ascent and merely passing along the ground. ”

“ These engines are made with endless diversities of details, though in most such simplicity of arrangement is secured, that a labourer of ordinary intelligence may, after a little instruction, be trusted with the charge of the engine; while their economy of fuel, efficiency, and cheapness are not exceeded in any other class of steam engine. ”

“ The machine is sailing along quietly and smoothly, when suddenly the controls become lifeless. You glance at your speed-indicator and at your engine-speed. Both show that the machine is travelling well above the minimum safety speed. This is apt to puzzle the beginner, for without warning there follows a sudden jolt. Your machine trembles like a frightened horse and unexpectedly leaps forward again. On a day like this you have to fight the machine all the time to maintain its equilibrium. ”

“ There is no species of manufacture, therefore, to which this machine is not applicable, from the power which spins the finest thread, or produces the most delicate web, to that which is necessary to elevate the most enormous weights, or overcome the most unlimited resistances. ”

“ 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 multitude of enthusiastic mechanics, and a larger multitude 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. ”

“ If the men at the separator can't handle it, get some one or get your boss to get some one who can. Your place is at the engine. If your engine is running nicely, there is all the more reason why you should stay by it, as that is the way to keep it running nicely. ”

“ How shall a machine be constructed that shall most efficiently embody, and accord with, not only those scientific principles, but also all of those principles of engineering practice that so vitally affect the economical value of every machine? ”

“ Thus, as we have seen, experimental investigation and analytical research have together created a new science, and the philosophy of the steam-engine has at last been given a complete and well-defined form, enabling the intelligent engineer to comprehend the operation of the machine, to perceive the conditions of efficiency, and to look forward in a well-settled direction for further advances in its improvement and in the increase of its efficiency. ”

“ We may even venture to point out definitely the direction in which improvement is now progressing as indicated by a study of these requisites, and may be able to perceive the natural limits to such progress, and possibly to conjecture what must be the character of that change of type which only can take the engineer beyond the limit set to his advance so long as he is confined to the construction of the present type of engine. ”

“ Uniformity and steadiness in the rate at which machinery works, are essential both for its effect and its duration. The first illustration which presents itself is that beautiful contrivance, the governor of the steam-engine, which must immediately occur to all who are familiar with that admirable engine. Wherever the increased speed of the engine would lead to injurious or dangerous consequences, this is applied ”

“ When a new machine is produced, we do not say, Why it only consists of a number of wheels and cylinders, therefore, surely there is nothing new in it! All the parts may be old, and yet the combination be quite new. To analyse an invention into its several parts, would be equivalent to finding that a poem was only composed of the letters of the alphabet, or the words in a dictionary. But there is another point of view not lightly to be passed [Pg xiv] over. Take this instance of the steam engine. ”

“ But original and comprehensive as were the views out of which these fundamental inventions arose, the exquisite and inexhaustible ingenuity which the engine, as finally perfected by him, displays in every part of its subordinate mechanism, is calculated to strike us perhaps with scarcely less admiration. It forms undoubtedly the best exemplification that has ever been afforded of the number and diversity of services which a piece of machinery may be made to render to itself, by means solely of the various application of its first moving power, when that has once been called into action. ”

“ The science of constructing steam-engines is now brought to maturity, so that an engine can be constructed to produce a certain power ; and yet, every year, new wonders are produced, not only in England, but in France and America. ”

“ Even the finest quadruple expansion engines, with all the modern devices for super-heated steam to augment their capacity, did not utilise more than 15 per cent. We engineer workers knew that if an engine were invented to economise this waste there would be a further reduction of labor—and this device came. ”

“ The results of tests are generally stated by giving the number of pounds of steam used per horse-power-hour, or by giving the work done by each pound of steam, a quantity which is directly comparable with the amount of work ideally obtainable, if the engine followed the perfect Rankine cycle already discussed. To make a complete engine trial the engine is caused to work not only at full power, but at various fractions of its greatest load. ”

“ But nowadays, through the all-round increase in efficiency that has been obtained, a machine will still fly upon its course without losing altitude, and respond to its controls, even should the number of revolutions per minute of its engine be reduced considerably. ”

“ When steam, water and fuel are being thrown away through the safety valves, it is a positive proof of the existence of either one or the other of the following evils:
Either the engine is too small for its work or too great for its man, and both the engine and the man would do better on short runs ”

“ If then travelling steam engines, with all the imperfections of an incipient invention—with the want of experience, the great parent of practical improvements—with the want of the common advantage of the full application of the skill and capital of the country—subjected to but one great experiment, and that experiment limited to one form of engine ”

“ The favourable effect which these reports have produced upon the vigilance of the several engineers, and the emulation they have excited, both among engine-makers and those to whom the working of the machines are intrusted, are rendered conspicuous in the improvement which has gradually taken place in the performance of the engines, up to the present time. ”

“ As regards the construction of the engine as a piece of mechanism, the principles and practice of good engineering are precisely the same, whether applied in the designing of the compound or of the ordinary type of steam-engine. ”

“ The engine as it exists at present is not, strictly speaking, the exclusive invention of any one individual: it is the result of a series of discoveries and inventions which have for the last two centuries been accumulating. When we attempt to trace back its history, and to determine its first inventor, we experience the same difficulty as is felt in tracing the head of a great river: as we ascend its course, we are embarrassed by the variety of its tributary streams, and find it impossible to decide which of those channels into which it ramifies ought to be regarded as the principal stream ”

“ This direction of application has been that which has, from the earliest period in the history of the steam-engine, attracted the attention of the political economist and the historian, as well as the mechanician, whenever a new improvement, or the revival of an old device, has awakened a faint conception of the possibilities attendant upon the introduction of a machine capable of making so great a force available. ”

“ You could not say, as you pointed to a steam-engine, "The usual power of that engine is two hundred horses; but once or twice it has surprised us all by working up to two thousand." No; the engine is always of nearly the power of two thousand horses, if it ever is. But what we have been supposing as to the engine is just what many men have done. ”

“ The most prominent of these additional mechanisms is a governor for regulating the speed at which the engine is to run; nearly all steam engines require a governor in some form or other, while for electric lighting and some other purposes it constitutes the main feature in the design of the engine. ”

“ In this case there can be no genetic connection; each engine is an independent thing, and the only connection is an ideal one in the minds of the inventors; that is, the idea of the steam-engine has gone through a process of evolution, expansion, and perfection, and most of the steps in the process have been embodied in real engines, so that together they form a manifestation or record of the changes that the idea has undergone. ”

“ Had it been otherwise, an animal running on its own wheels would have made its appearance on earth long ago. The shaft of the steam engine could be provided with numerous pulleys, each capable of driving a machine connected with it by a belt. Then arose that marvellous crop of mechanical combinations which brought about the age of mechanism, combinations which, in the last resort, can be reduced to sliding couples and turning couples, and can be catalogued by means of formulæ, like words in a dictionary. ”

“ Engines so arranged are termed triple and quadruple expansion engines, or multiple expansion.
The practical saving of a compound engine when its value can be utilized to the full is 10 per cent to 20 per cent. Small engines are seldom compounded, large engines nearly always. ”

“ We have now closed for an engine complete, of the power of twelve mules at a time, with suitable duplicates, chains, &c., for 210l. I very much wish for your engine to be set to work by your own workmen, to show the planters the simplicity and easy management of the machine, and also save the expense of an engineer, which will tend to promote their use. The engine will be set to work before it is sent off, and every possible care taken to execute it in the most perfect order. ”

“ Having traced the method of operation of the steam-engine, it is easy to discover what principles are comprehended in its philosophy, to learn what are known facts bearing upon its operation, and to determine what are the directions in which improvement must take place, what are the limits beyond which improvement cannot possibly be carried, and, in some directions, to determine what is the proper course to pursue in effecting improvements. ”

“ Scarcely a month has passed without suggesting some change in the details, by which fuel might be economised, the production of steam rendered more rapid, the wear of the engine rendered slower, the proportionate strength of the different parts improved, or some other desirable end obtained. The consequence of this has been, that the particular engines to which we have alluded, and others of the same class, without having, as it were, lived their natural life, or without having been worn out by work, have been laid aside to give place to others of improved powers. ”

“ Q.--Having now described the most usual and approved forms of engines applicable to numerous miscellaneous purposes for which a moderate amount of steam power is required, will you briefly recapitulate what amount of work of different kinds an engine of a given power will perform, so that any one desiring to employ an engine to perform a given amount of work, will be able to tell what the power of such engine should be? ”

“ Formerly, the power to drive a machine was derived from a very complicated arrangement of shafting and gearing brought from a distant engine. But by my system I conveyed the power to the machine by means of a steam pipe, which enabled the engine to which it was attached to be driven either fast or slow, or to be stopped or started, just as occasion required. It might be run while all the other machines were at rest; or, in the event of a breakdown of the main engine of the factory, the small engine might still be kept going or even assist in the repairs of the large one. ”

“ If we look back upon the developments of some such thing as the steam engine, we cannot fail to be struck by the extreme obviousness of each advance, and how obstinately it was refused assimilation until the machine almost invented itself. ”