A, is the boiler; B, fire-box; C, smoke-box, in which are placed the cylinders; D D, the cylinders (valve-box, and valves removed); E E, driving wheels; F F, connecting rods; G, crank axles; H H H H, excentrics for working valves; 11, framing of Engine; J, buffers; K K, safety valves; L, starting and reversing handle; M, steam cock for regulating speed; N N, brass pumps for supplying boiler with water; O O, pipes for conducting water from tender to pump; P P, leather hose between engine and tender; Q Q, bushes for axles; R R, springs; S S, guards for clearing rails; W W, links connecting the engine to tender
3. Experiments were subsequently made, intended to show that economy of fuel resulted from the use of a large fire-box; but the consequence was, that this part of the engine became so heavy as to require support behind it, and hence arose the re-introduction of a third pair of wheels, which had been previously abandoned as highly objectionable.
" Owing to the frequent occurrence of accidents with, and the pitching and sinuous motion of the four-wheeled engines, it was resolved to try the effect of six wheels, by putting an additional pair under two of the Company's old engines, namely, the Atlas, and the Mars." " The result of the experiment gave so much satisfaction, that I believe all the Company 's engines which were thought to be worth the expense, were made into six wheelers; and the engines which are now (1843) making for that line, are six wheelers. It is altogether erroneous, therefore, to say that the third pair of wheels was introduced on account of the use of large fire boxes."
4. The engine makers, generally, of the country had no choice of the form of engine, but had to conform to the plans of the directors or engineer of the Company, and did not examine minutely the merits of the new plan of construction, and engines continued, for some years, to be made ordinarily with outside frame, large fire-box, and six wheels.
5. It was the good fortune of the conductors of this foundry to originate the construction of four-wheeled engines, with inside framing, crank axles, and cylinders, placed in the smoke-box, all the practical and mechanical objections to the six-wheeled engines, and particularly with outside framing, having been foreseen at the earliest period. The first engine made upon this principle was manufactured in this foundry, in 1829, prior to the opening of the Liverpool and Manchester railway. As the principle of the four-wheeled engine thus made gained publicity, great alterations have been introduced, from time to time, in ordinary six-wheeled engines, and at last we find, which we may be pardoned for adverting to with some satisfaction, that in the latest invention of an eminent engineer, the outside framing is now being abandoned, or at least, that the inside framing has been adopted in that instance, and the large fire-box dispensed with.
In reply to paragraph 5, the "Practical Engineer" says, "I am not prepared to say that Messrs. Bury and Co. were not the first who constructed engines of ' four wheels, with inside framing, crank axle, and cylinders placed in the smoke-box,' considered as a combination of parts; but taking this statement in connexion with other parts of the circular, it is calculated to preduce a very false impression, and I have met with several persons who have been misled by it." " Every person at all acquainted with railways, must know that outside framing is of comparatively recent date, long subsequent to Messrs. Bury and Co. becoming engine makers. The reference made in the latter part of this paragraph to the use of inside framing, by an 'eminent engineer,' is one of the boldest things I eversaw. It can hardly be possible that persons engaged in the construction of locomotive engines so long and so extensively as Messrs. Bury and Co. have, can be ignorant of the fact, that Mr. G. Stevenson made engines with inside framing more than 30 years ago.
Even if they did not know that fact, can any body conceive it possible that they should so soon forget that the Rocket, and many other engines subsequently made by Mr. R. Stephenson for the Liverpool and Manchester Railway Company, had inside, and not outside framing! You will observe that it is not stated that that 'eminent engineer' is now adopting the inside framing for the first time, but that the outside framing is now being abandoned. The object of the authors of this paragraph is obvious enough."
6. The frequent variations in the construction of locomotives serve to prove that the designers of six-wheeled engines, with outside framing, are convinced that their plan was not a perfect one: whilst, in this foundry, the same plan has been continued with which we began, and to which others are now coming round.
7. This being, in brief, the history of passenger locomotives up to the present time, we think it due to ourselves to give the reasons why we have so perse-veringly adhered to our plan of engine with four wheels only, and inside frames, and we cannot do better than give the following compiled extract from a paper published in the transactions of the Society of Civil Engineers, and read before the society, March 17, 1840. It contains the statement of our opinions, of the soundness of which we had then had ample experience, and which still remain not only unchanged, hut strengthened.
8. Next to a good boiler, which governs the economy of fu 1, the most important point in the construction of a locomotive engine (inasmuch as it most materially influences the cost of repairs) is to connect all the parts firmly together by a strong and well arranged framing, so that they shall retain their relative position when the engine is in motion, and that it shall receive and bear the strain, and the concussions to which every part is subject. The inside framing possesses a great superiority in this respect over the outside framing, as it forms a stronger and more direct connexion between the cylinder, the crank axle, and all the moving parts; and it bears all the strain of the engine, without throwing any portion of it on the boiler, as is the case with the outside framing.