. APPLIED MECHANICS. 



[|.|:iVISO MACHINERY BT STEAM. 



non-condensing engine* are generally pn ;" rn-d. I'.ut. 

 <>n the other hand, where there U a plentiful Mi] ; 

 water, and where fuel is exp, ,- engine* 



are employed ; a* by a certain expenditure ,.f fuel, 



rtainly a greater amount of power generated w hen 

 the nU-niii U Cfi I"- i l.ir^f tnnniii (ton, 



flax, and flour nulls, br.-weries, and like establishments, 

 &m-engine U generally employed. Its advantage* 

 it in the accessibility of all its parts in case of 

 damage or repair, and the steadiness and regularity of 

 its n resulting from its inasMvvncsK and solidity, 



substantial and imposing look of a large beam- 

 engine is certainly, however, with many persons, an 

 argument for its use, where engines of less weight and 

 bulk might be applied with quite as great advantage. 

 The marine engine, having received great attention to 

 its perfect construction, has often with advantage 

 taken the place of ordinary beam-engines in manufactur- 

 ing establishments ; and we believe the only objection to 

 their general use is, that they are rather more expensive 

 in the first place. Where there is a deficiency of water 

 for condensation, it is necessary to provide large reser- 

 voirs, in which the water discharged from the air-pump 

 may have time to cool before it is again used in the con. 

 denser. Warm water, when used for injection, must 

 either be admitted in quantities so great as to impede 

 the engine by the additional work thrown on the air- 

 pump or, if limited in quantity, can only etl'ect partial 

 condensation of the steam, so that the piston is impeded 

 by the imperfection of the vacuum. 



The power of an engine required for manufacturing 

 purposes, necessarily depends on the kind of work to be 

 done, and its amount. A manufactory generally con- 

 tains numerous machines, like and unlike ; and unfor- 

 tunately very few accurate experiments have been made 

 as to the power required for working them. It is stated, 

 that in the cotton manufacture, one horse-power is suf- 

 ficient for 100 spindles of cotton yarn, and the machinery 

 necesaary for the preparation of the cotton ; and, again, 

 that one horse-power will work 12 power-looms. But, 

 every day, improvements are being made in the con- 

 struction of such machinery, and changes are introduced 

 anmiig the methods of preparing the material ; and it 

 therefore becomes difficult to assign any determinate 

 method of estimating the power. 



In the iron manufacture, steam-power is applied to 

 the processes of rolling, shearing, flatting, punching, 

 turning, planing, and the like. And so with operations 

 on other metals, on wood, and generally all crude mate- 

 rials, the facility of deriving adequate power from the 

 application of heat to water enables us to employ ma- 

 chinery instead of manual labour in a multitude of ways, 

 to as not only to execute works that could not have been 

 attempted without having such a force at command, but 

 to do so with an economy and ease that could not other- 

 wise be attained. In all these manufacturing operations 

 it is essential to the safety as well as to the accurate 

 working of the machinery, that the speed of the prime 

 mover should !, uniform. 



Where there are numerous machines driven by the 

 same power, it may often happen that several are in 

 operation at once, while at another time none may be at 

 work. To overcome the resistance caused by suddenly 

 bringing a heavy machine into action, as in the case of a 

 et of rollers for preparing iron, and at the same time to 

 prevent the dangerous increase of speed that would result 

 from suddenly throwing it out of work, it in essential 

 that there should be a good governor and a very heavy 

 fly-wheel. The fly-wheel acts as a reservoir of force in 

 the one case, ready to give out a portion of its momen- 

 tum when the additional resistance conies upon it ; and 

 an a reservoir of resistance or inertia, in the other case, 

 n-ady to absorb a portion of tho unnecessary power. 

 The governor, again, permits the supply of addition:,! 

 team to the cylinder as soon as the velocity of the 

 engine begins to undergo diminution, and checks or 

 tie* the supply whenever the speed rises above the 

 average. 



i the power required is small, or under circum- 



stances where there is a ditliculty in (applying water for 

 condensation, or where there would bo a i van- 



tage in having any complicated machinery to be att 

 to, it is usual to employ non . these 



l.,-in.' more simple, are less costly in the first place, less 

 liable to derangement and wear, and more easily nnder- 

 I stood and managed. It is true that for a given amount 

 of power, the expenditure of fuel is somewhat greater 

 than whe.ro tho steam is condensed; but with a good 

 boiler generating steam at a pressure of 40 to GOlbs. if 

 the cylinder be made of considerable size, and the steam 

 cut oil' at an early part of the stroke so as to act 

 expansively, the excess of fuel expenditure is not great. 

 For agricultural purposes, in the colonies, or generally 

 in districts removed from engineering establishments, 

 simplicity is of more importance than even economy of 

 fuel. Many of these non-condensing engines, from 5 to 

 15 horse-power, are made portable, so that the power 

 may be readily brought to the work instead of the work 

 being brought to the power. Tho portable engine con- 

 sists of a cylindrical boiler, perforated with flues or 

 tubes like that of a locomotive, mounted on wheels, with 

 a direct-acting engine laid horizontally upon the boiler, 

 or arranged in some convenient way for lightness and 

 economy of space. For thrashing and winnowing corn, 

 draining or irrigating laud, brick and tile making, and 

 field operations generally, these engines are very ser- 

 viceable, especially in cases where the work of a farm is 

 not enough to keep an engine constantly employed, and 

 where the same engine may do duty throughout a con- 

 siderable district. We believe, however, that as agricul- 

 ture approaches more to the condition of a manufactur- 

 ing art than it has hitherto done, the fixed engine will 

 gradually supersede those that are portable ; the farm 

 buildings will become the head-quarters of the various 

 operations ; the materials will be brought thither to be 

 operated on ; and agricultural processes will be carried 

 on with tho regularity and precision of other branches 

 of art. Of late years, many persons of high standing 

 and energetic character have devoted themselves to the 

 furtherance of this object ; and their example is being 

 generally followed throughout the country. His late 

 Royal Highness the Prince Consort erected a very com- 

 plete farming establishment near Windsor. A fixed 

 engine there puts in motion a train of machines for 

 thrashing, dressing, and grinding corn, cutting chat!', 

 bruising beans and oats, steaming the food of ca 

 and other processes, all systematically and economically 

 arranged ; and similar plans are adopted iu many other 

 places at home and abroad. 



III. LOCOMOTIVES. In no application of steam-power 

 has greater ingenuity been manifested than in loco- 

 motive engines. The great essentials of a locomotive 

 are, lightness, compactness of strength of construction, 

 rapidity of action, and facility of management. Some 

 of the earliest attempts at these engines wen necessarily 

 rude and imperfect. ; but the rapid extension of the 

 railway system, and the immense advantages derived 

 from speed in the transmission of passengers and goods, 

 have hurried on improvements so quickly, that in a 

 very few years the locomotive has risen to a high degree 

 of perfection. For some time it seemed difficult to con- 

 template the possibility of covering the land with a net- 

 work of iron-ways, extending over many thousand miles 

 in length ; and accordingly attention was chiefly devoted 

 to the construction of locomotives for running on ordi- 



roads. Some of the engines made for this purpose 

 were tolerably successful in their operations, and em- 



d in their construction a great amount of ingenuity, 

 which has not been without its use in leading to the 

 more perfect locomotive of the present time. Even when 

 railroads began to be formed, the employment of M 

 on them was a doubtful question, and their most san- 

 guine promoters scarcely dared to hope for a speed ex- 



Bg Id miles an hour, or to expert that i 

 tratlic would equal in importance the con\. 

 heavy goods. It was feared that the friction of an iron 

 wheel on an iron road would not be sullicicnt to mi 

 onward the locomotive itself, much less a heavy train of 



