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LATROBE'S IMPROVED PLAN OF RAILWAY SUPERSTRUcture.

(ths of an inch) into the continuous bearing, so that their tops are flush with the upper surface of the latter, and the bottom of the rail bears fairly upon both.

The chairs have each a projection going up vertically into the hollow of the rail, and two horizontal semi-circular projections on their ends to fit into half round mortises in the wood, to prevent lateral motion.

The centre chairs, moreover, have two square projections on the upper surface, which fit notches of the same dimensions (ths of an inch square) in the feet of the rail, to confine the bars from longitudinal movement.

The whole of the track is laid upon, and partly imbedded into, a ballasting of broken stone, composing a mass of open material-entirely pervious to water-10 feet wide at bottom, 8 feet at top, and 1 foot in depth : the lower part consisting of stone broken to pass every way through a 2 inch ring, and the upper part of such as will in like manner pass a 4 inch ring: the base of the ballasting is about 4 inches below the bottom of the sub-sill, and its top, level with the upper surfaces of the cross-ties, or 3 inches below the top of the continuous bearing. The distance between the iron rails, or the gauge of the railway, is 4 feet 8 inches.

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References to the Engravings. A, general plan of the superstructure; B, side view of ditto; C, transverse section ditto; D, side view at the joint of the rail, showing the rail and its fastenings to the contiguous bearing; E, cross section through the continuous bearing at the joint of a rail; F, plan of the joint chair; G, end view of ditto; H, plan of the centre chair; I, end view of ditto; J, plan of the bearing plate; K, plan of the screw bolt; L, cross section

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through the rib of the bearing plate; M, plan of the nut and washer.

Scale of A, B, and C, 4th of an inch to the foot, the remainder, being the details, are drawn quarter-size.

Remarks by Ellwood Morris, Esq., C. E.

We invite attention to the foregoing plan of railway superstructure, as embodying in a great measure, the experience acquired by the railway practice of the country." *

In 1838, Messrs Knight and Latrobe, the distinguished engineers of the Baltimore and Ohio Railroad, were specially commissioned to visit the most important railways in the United States, with the view of availing themselves of the experience of the whole country, in framing a plan for a new track, then about to be laid between Baltimore and Frederick, to replace the original superstructure, of which the wood work had decayed and required renewal, and the stone continuous bearings had ceased to give satisfaction.

The results of the observations of these engineers were reported to the Directors of the Baltimore and Ohio Railroad Company, in an able and elaborate memoir they discussed in detail the merits of the various plans of railway which came under their observation; and ultimately recommended a superstructure having a sub-sill and crossties, surmounted by a rolled iron H rail of 50 lbs. to the yard, in lengths of 18 feet, with angular joints, and for which the crossties formed isolated bearings of 24 feet asunder, from centre to centre, except at the ends of the bars, where the bearings were made but 14 feet, conformably to Barlow's experiments; this superstructure was designed to be embedded in a broken stone ballasting, of 1 foot deep; and many miles upon this plan were laid in 1839, and have since been in constant use.

Though there are, of course, some variations in the details of the fastenings, &c., the superstructure above described differs from that adopted in 1838-at the suggestion of the same gentlemen-mainly in two particulars :

From an inspection of the railways of general trade, which have been the longest in use, the writer is strongly disposed to conclude, that it will eventually be found advisable in such railroads as carry a very heavy traffic, and the earthworks of which have acquired the requisite stability, to lay the superstructures in a bed of concrete, as has been suggested in the London Mechanic's Magazine; the expense of which, in such cases, would probably be compensated by the additional smoothness of surface, and freedom from derangement, which such a foundation might fairly be expected to impart to railways.

1. In having a continuous bearing of timber beneath the rolled iron rail, upon which it rests throughout its length.

2. In the adoption of the U bridge, or trough section, for the iron rail, in lieu of either the T or H patterns.

These two essential variations from the plan of the railway superstructure, recommended by Messrs. Knight and Latrobe, in 1838, are fully justified, if not absolutely demanded, by the practical experience upon these points, now dawning upon the country; which at an earlier period in the history of railways could not perhaps have been foreseen, and certainly was not anticipated.

With regard to the first point, a close observation of such of the American railroads as have been the longest in use-possessed of the largest trade-and travelled by the heavy locomotive steam engines, which are now so common, will fully satisfy any professional man, that the alternate succession of "rigid points and flexible spaces," which inevitably results from the employment of isolated bearings, tends to a more rapid destruction, both of the locomotive machinery and of the road itself, than is likely to ensue, where the iron edge rails are sustained upon continuous bearings of timber of heavy proportions; which plan has also the recommendation of having already been practically tested upon the Baltimore and Port Deposite, and Washington branch railroads in this country, and the Great Western, and London and Croydon railways in Englandwith satisfactory results in each of these cases, so far as the writer is informed-besides being employed upon some other important railways in America, which are now in the course of construction.

Concerning the second point, or the sectional form of the rail-we will observe that the top table of the bars, upon which the wheels run, in the T and H forms-being supported in the centre alone by a single upright stem, in thickness about one-fourth only of the width of the head-soon crushes off on one side or the other of the centre, and renders it necessary to reverse the position of the bars.

On the Baltimore and Ohio Railroad, as the writer is informed, already has occasion been found to reverse the position of a number of the bars (of the track laid with the 50 lbs. H rails in 1839) whose inner flanges have partially peeled off! and upon the Columbia Railroad, which has been but seven years in use, rolled iron rails of the T and H forms may be seen in every stage of destruction; and though a portion of the disintegration which may there be witnessed, is undoubtedly owing to the intrinsic structure of rolled iron, and hence can only be

postponed, and not annihilated, by any change of form or pattern; still it must be admitted, that if the top table of the rail had been so supported as to prevent it from being forcibly disrupted from its vertical stem, and thus render it subject alone to the natural exfoliations, which occur when malleable iron is exposed to a series of great rolling weights, the durability of that railway would have been essentially increased.

The sort of support to the head of the rail, which practice now shows to be necessary, is given by the double stems of the U section, and not by the single one of the T figure; consequently, it seems to the writer, that experience on existing works demands in future ones the adoption of the former pattern, in outline at least; for it is a question which time alone can determine, whether we shall not finally come to a solid bar rail as the best; for the present, however, it will probably be the proper course to use the U rail as now rolled hollow, in which form, as it can be made as light as the T and H patterns, its superior durability will gradually cause rails of the latter figure to pass from use, and give place to those of the former pattern, unless a superior section should meanwhile be introduced.

To support these views, it would be easy to cite further examples of the decay of rails of the T and H forms; but it seems scarcely to be necessary, and upon the whole, we are disposed to conclude that the experience of the country, up to this time, indicates the propriety of adopting, in future railway superstructures, a continuous bearing of timber laid with a U rail, upon a suitable substructure, in preference to any of the other plans now in use, most, if not all of which, seem on trial to possess fewer practical advantages.

In fine, the new superstructure of the Baltimore and Ohio Railroad appears to combine in its plan a sufficient provision to satisfy the most important requisites, in favour of which the railway practice of the country has pronounced, viz.

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1. That to guard against disturbance by frost or rainy weather, the superstructure ought to be embedded in a ballasting, entirely pervious to water, and of a sufficient depth.

2. That to prevent the track from spreading laterally, numerous cross-ties should be employed.

3. That to prevent unequal settlement of the cross-ties, (which also form detached supports for the rails or continuous bearings,) sub-sills of wood are indispensable.

4. That to render the road more smooth, more equal in strength throughout, capable of carrying greater weights than roads of

MESSRS. LILLIE AND SONS' BOILER FURNACE.

isolated bearing, and exempt from "rigid points and flexible spaces," continuous bearings of timber ought to be employed to carry the iron rail.

5. That the iron rail itself ought to be of the U pattern, (either hollow or solid,) as superior in durability to any other known form of section now in actual use, whilst it is very stable in position, and cheap in its fastenings, when properly laid.

6. That the iron rail-bars ought to be firmly fixed at their middle parts, to cause expansion and contraction to take place both ways from their centres.

MESSRS. LILLIE AND SONS' BOILER FURNACE-INVENTED BY MR. PARKES.

Sir,-In your 976th Number, I observe a letter from your correspondent, "H. H.," from Manchester, accompanied by an engraving, in which credit is taken for the furnace, as an invention of modern date. Now, sir, I cannot avoid stating that your correspondent, while he takes credit for "simply communicating the result of private and personal experience, without fee or reward," has omitted to mention that this very plan, as adopted by Messrs. Lillie and Sons, is neither more nor less than that of Mr. Josiah Parkes, patented above twenty years ago it is, in fact, as given in your last Number, identical with Mr. Parkes's patent.

It may just be possible that your correspondent was not aware of the fact. In justice therefore to Mr. Parkes, I beg to add this fact to those stated by "H. H." In this instance we have a striking corroboration of the truth of your observations respecting the injurious effect of the "Leeds Smoke Nuisance" pamphlet, which has thus brought forward, under the name of Lillie and Sons, a plan of twenty years' standing, and which, though possessing unquestionable merit, and in many instances eminently successful, under careful management and good "looking after," has, nevertheless, not carried the public with it, and has literally gone into disuse since Mr. Parkes himself ceased to take any interest in the matter.

"H. H." informs us that "a similar plan may be also seen at Messrs. Horrocks', of Preston." It would have been but common candour to have stated that that very furnace of Messrs. Horrocks' was actually erected under Mr. Parkes's own direction.

"H. H." observes that "in a former furnace which they had with Stanley's feeders, the consumption of coal was 20 lbs. per horse-power per hour; they now have a

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more regular supply of steam" (with Parkes's plan of furnace and air feeder by a double or hollow bridge,) from 13 lbs. of coal per hour; a saving, in this instance, of 35 per cent.; but what they strangely "estimate at 20 per cent. average." Now Stanley's plan has nothing to do with the admission of air, which is the very essence of Parkes's plan. Stanley's is in fact but a mere mechanical feeder, and is any thing but a "smoke burner."

"H. H." concludes by "relying on your willing co-operation to make this very useful plan as extensively known to the public as it is freely presented to them." To this I have only to add, that this plan so freely presented to them may be seen in the London Journal of Arts as the undoubted and legal property of Josiah Parkes, the patentee; and that "H. H." has no right to claim merit for presenting to the public what did not belong to him.

Query. Was this the boiler which lately exploded on Messrs. Lillie's premises, owing, as was stated at the time, to a deficiency of water?

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Sir, I have read in the number of your Magazine for the 23rd of April, the letter of your correspondent "H. H.," which is so calculated to mislead, that I feel assured you will readily admit a correction of its absurd errors, in relation to "Messrs. Lillie and Sons' Boiler Furnace," and certain trials of "Stanley's Feeder."

Your correspondent has made a wholesale appropriation of the paper in Mr. West's pamphlet without acknowledgment, and has thus managed to make what was already sufficiently mysterious in itself still more confused. The case appears to be simply this: Twenty years ago Mr. Josiah Parkes introduced a split bridge, admitting a sheet of air to the gases immediately as they passed over the bridge. This plan, long practised, is exceedingly well known. At Messrs. Horrocks' and Co., Preston, it has been used ever since its first introduction. This plan of Mr. Parkes', Messrs. Lillie and Sons', engineers, have introduced at their works, in Store-street, Manchester, their furnace possessing no other recommendation than good workmanship, for certainly no improvement of any kind affecting the principle of the invention have they introduced. The very same kind of furnace, as set up

during the existence of the patent, may still be seen at many old establishments in Manchester. With this explanation, what becomes of your correspondent's "appeal," in behalf of a piracy, for such it would be, if fortunately he were not excusable for his errors on the ground of his extreme simplicity and ignorance?

There is some incongruity in the account given in Mr. West's pamphlet, which opens with the remark, that the parties in question "have communicated a method, never before published," while directly afterwards we are informed respecting the main feature of the plan, that the "air is admitted into a passage through the bridge (the split bridge of Parkes' expired patent)." Mr. West may naturally have thought, that the hitherto secret process pursued at the furnace at Store-street, and probably forwarded to him with a neat drawing and the inviting announcement 66 never before published," must in some of its other details be a unique gem of engineering skill. All Messrs. Lillie and Co. may have meant to be implied, was, no doubt, neither more nor less than the simple fact, that they then made known, for the first time, their having recurred to an old invention with satisfaction, never supposing that any one would start up to laud them for "a plan"-the result of "their own private and personal experience."

Your correspondent, who commences in a very pathetic strain, eulogizing those who do not make "a traffic of their knowledge or skill," evinces the possession of very little of either to traffic in, himself. He adopts a sweeping censure of Stanley's Feeder, and talks of the comparison of the present with "a former furnace," and he might have added also, a former boiler. Nothing can be more unsatisfactory than such unfair and unequal comparisons; neither the same boiler, the same furnace, nor the same grate being employed to test the consumption of the coal.

Mr. Josiah Parkes, C. E., whose invention is here alluded to, speaking of the Argand Furnace of C. W. Williams, Esq., (see the No. of Mech. Mag. for Oct. 9, 1841,) very ingenuously observes in a published letter to that gentleman :

"I am now desirous only of making a few observations on the general introduction of your system, which cannot fail to benefit its employers and improve the salubrity of the atmosphere.

"I am the more anxious to do you this justice, as it has been currently and confidently stated, that your plan differs inmaterially from that patented by me, more than twenty years since. This is not correct. You have provided an important addition to my plans: viz., a more immediate and intimate diffusion of the air amongst the inflammable gases at the only place where these gases can be encountered and inflamed. This is a chemical improvement which directly leads to a practical advantage, as compared with my plan, viz., that you

Your correspondent seems to be a very young "smoke doctor," for he first checks himself in speaking of smoke as being capable of "combustion," and then with admirable complacency (our plagiarist) acquaints us, that this plan, at Store-street, "is stated to have the effect of completely consuming the smoke." This little mosaic of right and wrong may amuse the critic, but it is not with any such feeling that I have endeavoured to expose, as briefly as possible, the most material errors committed in this instance, in a matter which is just now exciting deserved attention, and when we require the direction of correct information.

It is important to bear in mind, that furnaces of this description, to be rendered available on the best principle, are only charged with coal at starting; it is a system of slow combustion, and requires large grate surface and ample boiler room, which circumstances are apt to be overlooked; and it generally happens that it is only when parties are on the point of "coming to business with the engineer, to traffic in kis time and material, if not his "knowledge or skill," that the disappointed manufacturer finds he cannot take down his Stanley's Feeder, or enlarge his grate, or get a new and more capacious boiler, or, in short, avail himself of "H. H.'s" suggestions. I am, Sir, yours truly,

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I. B.

CASTING SPECULA-MR. LASSELL'S OBSER

VATORY.

Sir, I observe in No. 965 of the Mechanics' Magazine, dated the 5th of February last, a letter from Mr. Robert Jones, of Newcastle, which refers in a complimentary manner to a communication I formerly made to that publication on the art of casting specula, and expresses a desire that I would prosecute the subject and describe the methods of figuring and polishing.

I have long been interested in the construction and use of Reflecting Telescopes, and if I have been able to devise any im

have no need to change materially the habits and practice of the fire men. My method requires for its perfect action a specific mode of charging and managing the furnace, which it was difficult to induce the masters to enforce or their servants steadily to practise.".-ED. M. M.

By the engraving it appears Messrs. Lillie and Sons have a wagon boiler, only 27 feet long, with a fire-place having 2 feet dead plate, 9 feet bars, and I foot 3 inches clinker plate, in all 12 feet 3 inches. Seeing these disproportionate measurements, I am led to believe that the principle carried out applies equally to the boiler being unnecessarily large for the engine, and most likely even the engine not working to its estimated power.

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175-176-177-178.

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