this point, we hope soon to be able to speak || to wit: 225 part of weight of engine and more definitely. the regular curve represented by the continued line A. B. D. E. F. and N., and in the latter case the irregular curve, represented by the broken line a. b. d. e. f. and n. The first coinciding, as would naturally have been anticipated, with the regular decrease of the effect produced under a gradual in tender, and part of the cars and their We desire to call the attention of our loads. And 2dly, The resistance caused readers to an article from the Journal of the by gravity which occurs upon inclined roads, Franklin Institute, in relation to this en- and which corresponds, (according to the gine, published in No. 13 of this Journal- established principles of mechanics,) with and also to one in the same number, signed the size of the angle of inclination. "HIERO," as they will, we believe, with To reader the preceding principles appli-crease of the elevation of the plane on this statement of facts, tend at least to shake, cable, the inclination of the road must be which the power operates, while the latter if not to dispel, some of the prejudice within that limit on which the friction of is evidently in direct violation of the law against, or disbelief in the power and utility the wheels of the engines upon the rails is which connects cause with effect, in the of, this engine. If more particular informa-sufficient to allow of the exertion of the case under consideration. tion is desired, it may be obtained by ad- full working power of the engine. dressing, post paid, William Avery, or E. Lynds & Son, Syracuse, New-York, or Mr.|| Joseph Curtis, the agent for this city, or the Editor of this Journal. By the way of comparing it with other engines, we shall feel greatly obliged to any gentleman who will give us a statement of the water and fuel used, and labor performed, by a piston engine of fifteen horse power! When received, we will lay it before our readers. [ED. R. R. JOUR.] THAMES TUNNEL.-We commence, in this number, a concise description of the Thames Tunnel, with views-and shall continue it in a subsequent number-after which it will be published in book form. For the Railroad Journal. STRICTURES ON THE REPORTS OF THE ¡No. III. According to the principles above laid down, and assuming the gross load upon a level to be as above stated, to wit: 75.25 tons, the weight of the engine and tender being taken at ten tons, the following results are obtained: The preceding is conclusive as to the manner in which the table presented in the Report was formed. The process as declared in our last number, must have been an empirical one, as calculations made upon true principles could never have led to such discordant results. We have dwelt longer upon this branch of the subject than its importance would perhaps seem to demand, but as the statements in the Report were evidently put forward with some pretension to science, we have felt it a duty to lay bare the foundation on which that pretension rests. We now proceed to give a statement of the comparative force of traction of engines on the Baltimore and Ohio Road, as deduced from the experiments referred to in our last No. Inclination of Road in given in the Report deviates from the truth Mile. Engine as as-Arabian En-Geo. Washing. We again quote from the Report of John B. Jervis, Holmes Hutchinson, and Frederick C. Mills, on the comparative merits and cost of Canals and Railroads, Doc. 296, p. 33, of the last session of the N. Y. Legis-cal and mathematical principles. Indeed Level 75.25 lature, as follows "On a level the gross load will be Feet the results themselves exhibit this fact on 30 27.24 60 13.92 70 11.31' We demonstrated in our last No., that the absolute power of the locomotive engine as exhibited in the above table, whether upon a level or inclined road, was rated altogether too low, being from 50 to 100 per cent. short of the results obtained by experiments actually made for months previous to the time when the Report in question was rendered. We present the table a second time, for the purpose of showing that the relative results therein given for different inclinations, could not have been estimated by correct formula, and were not in accordance with the "most approved" experiments and facts, as they existed at the time the Report was written. It will be obvious to most of our readers The following are the second differences: 13.37 5.51 2.82 1.61 1.02 0.69 To render the discrepancy more apparent we have framed the following diagram, in In determining the resistance to be encountered in the movement of a train of cars, under the circumstances as assumed in the table, two things are to be considered. which the second differences in the second 1st. The resistance arising from friction, line are represented respectively by the orand the want of perfect smoothness and dinates HA, SB, RD, &c., and those in the regularity in the rails and wheels, which first line by Ha, Sb, Rd, &c. Connecting we will assume the same as in the Report, "the extremities of the former, and we have The rates here given for the Geo. Washington and Arabian engines, for different ascents, are below the actual performance of those engines. This is principally owing, we presume, to the fact that the friction, instead of being of the gross load, as assumed, is probably the or part. The second column contains the corrected results as ascertained above, for different 1 inclinations, the gross load being the same as assumed in the Report, viz: 75.25 tons. The fourth column shows the force of traction of the Arabian, and the sixth that of the Geo. Washington engine. The Arabian was in operation, and an official statement of its performance rendered for months previous to the Report under consideration being made. We expressed, in our last No., our surprise that the improve. inents on the Baltimore Road were not referred to or noticed in the Report. Had they been fairly presented, the complexion of the results given in the Report would cessarily be greater. Such an engine will mand the top of the highest building in that || have been materially changed. convey a load up an inclination along which division, and of capacity sufficient to sup The gross load conveyed on a level, in- a weaker engine would not be able to pro- ply the largest fire ascertained for two stead of 75.25 tons, would have been 113 tons, pel its own weight-or an engine may be hours-a small steam engine or other ap. an increase of 50 per cent. At 30 feet per so weak as to have its power entirely ex- paratus would be required to raise the mile, 39.72 tons instead 25.15, being an in-hausted on a very moderate inclination. In water, and if it were a steam engine, it crease of nearly 60 per cent. At 70 feet per either case the absurdity of the principle could always be heated and in operation mile, 17.70 tons instead of 9.70 tons, an in-asserted in the Report is apparent. We within the time specified, renewing the crease of nearly 80 per cent. It is true that are not surprised at this; it only comprises supply. From this reservoir four inch pipes the Arabian engine was heavier than the what we have already had occasion to infer, ||would branch into every street of the divione assumed in the Report, being 7 tons, that the mechanical principles of the opethe latter being 6 tons, but it had one and ration of engines on inclined roads could one third times the power. not have been thoroughly understood by the writers of the Report. A difference so great, it will be at once perceived, would have materially affected] the cost of transportation upon Railroads; as exhibited in the Report, the reduction in the expense being greater in proportion u pon the higher or steeper grades. sion, and at the corners of all the streets, and within frequent distances on these streets fire plugs would be placed raised above the pavement, occupying but little space and It is almost needless to add, that the ab- having quadration cocks, within a proper solute and relative cost of transportation case, with a common key, one of which per ton per mile, on different inclinations, would be in the hands of the foreman of as exhibited in the Report, is necessarily every hose company, and one also lying erroneous. The manner, likewise, in which with some respectable house in the neighthe cost of transportation on different incli-borhood. No part of this water would nations is represented, is calculated to mis- be permitted to be used for any other lead those who are not particularly conver- purpose; small pipes of 1 or 2 incl » sant with the subject, since no allowance diameter would be carried into such properappears to be made, or intimation given, of ties as desired them, running up the inside of the very great saving in power in descend- the front wall to the top of the house, and ing, which invariably occurs in a reciprocal having a communication with each story, trade. always open, and charged when necessary by means of the stop-cock on the street. 'These and various other arrangements easily suggested could very commodiously and profitably be introduced. In the sixth column above, are the results deduced from the performance of the Geo. Washington engine. This engine was constructed subsequent to the rendering of the Report. The statements in relation to it are introduced here with a view of exhibiting the present state of improvements in the application of locomotive steam power upon Railways. It is presented likewise We shall resume this subjeet in our next for the purpose of exhibiting to our readers || No., and examine particularly into the printhe character and extent of the improve-ciple adopted in the Report of reducing inments which ha ve been made upon the Bal-clined roads to equivalent level ones. timore Road, within the last three years, and impressing their minds with the degree "There are engines of a larger size than the one assumed, but it is the most approved at this time in reference to the weight of engine and the weight of the working wheels. This, however, is unimportant, as the comparison will not be at all affected by varying the power of the engine. The ratio between a level and the ascents will remain the same notwithstanding." WITH WATER. OWEGO. A very important item of the city water. is at present used to extinguish fires-this as any other. My opinion is, that the Fire Department, to be effective, should have the entire control of the water appropriated to its use: at present the individual companies are beautifully arranged and the engines ably manned, yet in such a city as this, there is wanting a more complete sys S.D. Boston, Feb. 18, 1836. [It has been objected to the use of salt water-that the pipe stop-cock, and all cocks of metal liable to its contact are injured, and in some instances rendered useless. The great injury to furniture, &c., in houses deluged with water, (as is often the case,) to prevent the spread of a conflagration. However, salt water is better than no water.] of credibility and i aportance to be attached ON SUPPLYING THE CITY OF NEW-YORK water might as well be salt or river water to the performancess of the Arabian engine, and also for another purpose, which will To the Editor of the Railroad Journal: appear hereafter. The power of the Geo. Sir, The supply of water now being Washington was two and a half times that brought into New-York from the Croton of the engine assumed in the Report, while river, will be very ample and of the best its weight was only one third greater. quality, and it will doubtless, by admitting We will conclude this number by com-of a more copious supply in cases of fire, menting upon the following, pages 33 and contribute as well to the further security ||tem of defence against this destroying ele34 of the Report: of property as to the general improvement ment than at present obtains. Compared of the health of the city. I have always, with the amount of property annually conhowever, inclined to think, with what pro-sumed, the cost of such an experiment priety remains to be seen, that that portion would be but a trifling tax. of the water necessary to the supply of the Respectfully, Fire Department, considering the great amount of property annually consumed in this way, should be seperate from that used for family purposes; in fact, that for the extinction of fires there should be a distinct supply and mode of supply, distinctly governed and independent of the contingent accidents which sometimes affect the other. In view of this, the excellent waters of A glance at the statements above given, the Croton would be reserved simply for the in relation to the powers of the different personal use of the inhabitants-a system engines, shows that the gross load which of fire police would be established containthe Geo. Washington engine is capable of ing within itself all essential requisites, conveying up an inclination of 70 feet per and capable of progressing in improvement mile, has a ratio compared with a level one independent of the control or opinions of and a half times that of the engine assumed other departments. This system, subject as in the Report, and for an inclination of 100 a whole to the city, had better consist of feet per mile, double that given in the Re-various independent divisions, each conport. It is obvious that as the power of the nected with the North and East river. My engine is increased, the gross load conveyed ideas in the present immature view of the will be greater compared with its weight, subject, would be to attach a reservoir to and that the effect produced on any given each division, situated on the river, and The report, judging from the extracts, inclination compared with a level must nehaving its tank sufficiently raised to com-promises much useful information on the The assertion here unequivocally made, that the ratio of the effect produced between a level and the ascents is not affected by the power of the engine, is incorrect both in theory and practice. PROFESSOR BARLOW'S REPORT ON RAILWAYS.-) -In the London Mechanics' Maga. zine for February, which has just come to hand, we find some extracts from the Report of Professor BARLOW, who was appointed by the Directors of the London and Birmingham Railway Company to visit the Liverpool and Manchester Road for the purpose of ascertaining the best form of rail, chair, &c. &c. ་ Since the publication of his first report (of which we gave a full abstract in No. 612), Mr. Barlow has been again engaged by the Directors of the London and Birmingham Railway, "to visit the Liverpool and Manchester Railway, to view that line, and advise this Board as to the weight of rails, the description of chairs and fastenings, the distance of the supports, and the size of the blocks that he would advise the Directors to adopt; and to accompany such advice with any observations generally on the subject." subject, and we shall endeavor to obtain it||men themselves, whose judgment must suf-secure, were only of a certain amount; but and publish it entire. fer depreciation by such discordance. Opin-when the rails were unlevel, or other irreguions derived from long experience are ex- larities occurred, some lurch would take ceedingly valuable, and outweigh all oth- place, towards the middle or end of the ers, while they are consistent with facts train, which would strike the rail with suffiand with each other; but they are worse cient force to throw up the index to nearly than useless when they lead, as in this in- double its previous amount, indicating, of stance, to directly opposite conclusions. course, that it had, in the case in question, "In making these remarks, I beg to be sustained a deflection nearly double what it understood as intending no disrespect to the would have done with the same weight in a opinions of practical men generally, but quiescent state." simply to show that it was impossible, in this case, for me to be guided by them, and thereby to justify the plan I soon determined to adopt; viz. to avoid, as far as possible, argument founded on mere hy pothesis, and to substitute for the latter, facts drawn from actual experiments, which should be made publicly, registered generally, and witnessed by any one interested in the decision; and moreover, as I intended to rest my report entirely on these data, I resolved to offer no opinion, till I had time to analyze and compare my results. I am not certain that this plan of proceeding was quite what the deputation most approved, but I feel convinced that it was the only way in which justice could be done to the inquiry, and confidence obtained for the decision." Accordingly, accompanied by two of the London Directors, and met at Liverpool by two of that town, he entered on his task, furnished by the liberality of the Liverpool and Manchester Railway Company with every necessary facility and accommoda tion. The following extract, besides showing the necessity of the investigation, presents a vivid and faithful picture of the uncertainties and contradictions into which practical men fall when they despise the help of theorists, while it gives, and on proper grounds, the weight unquestionably due to the opinions formed by these same practical men from constant observation: erroneous ideas. Numerous and varied experiments with this instrument, while they indicate a small increase of deflection with increase of velocity, seem also to have ascertained that it is too small to need much addition to the strength of the rails; for on comparing these observations with those made at Woolwich with quiescent weights, it may be doubted whether, when allowance is made for the manner in which the deflectometer was used, any real excess of deflection was occasioned by the passing load. This, however, where the deflection was 40 per cent. addiwas not the case with the joint lengths, tional; it is not suggested how this is to be prevented, but it is attributed partly to the looseness of the chair and block. It seemed desirable to know, whether the the outward rail in curves, required an addeflection produced by lateral pressure on dition to the strength of the rail in that direction; for this purpose a deflectometer was constructed of a somewhat different shape. cient for their work in other respects, would The result, however, was, that rails suffinot fail under this strain, so that the subject needed no further attention. The dimensions of a railway-bar to sup "We met as appointed, at the Liverpool port any given quiescent load had become station of the Liverpool and Manchester pretty well known, but practical men doubtline, and employed the first day in examined and differed as to what was required by ing the state of the rails, chairs, and blocks, an engine and train in motion, whether modes of fixing, and other particulars. In more or less, and how much. Knowing the course of this examination, I took the that the results of theory, when opposed to opportunity of inquiring on the spot the their previous opinions, obtain little confiopinion of the resident engineers, con-dence from practical men, and would, theretractors for repairs, workmen, and others, fore, be slighted by part at least of those The deflectometer rendered very apparelative to these several points; but I was for whose guidance the inquiry was under- rent the importance of placing the blocks much disappointed to find those opinions, taken, the Professor wisely resolved to found in every case opposite to each other. Until in most instances, discordant, and in many his Report on experiments alone; and this and other precautions are taken, the directly contradictory; a circumstance the these are happily such as may be repeated constructors of railways must be content to more remarkable, as one would have thought at any time, and at small expense, till the use rails very much heavier than the work that five years' incessant practice would results from them are established beyond of the road actually requires :have been sufficient to eradicate many early dispute. A horizontal lever, of which the "In consequence of the imperfection of arms were as 10 to 1, was mounted between these parts (the blocks, &c.), a strain is oc"I am not myself a practical man, but centres on a plank; its short end was placed casionally thrown on the rail which produces from my situation and pursuits I have been in contact with the under side of the rail, a deflection about double that which belongs for nearly thirty years in almost constant and the other showed the deflection ten to the load in question. This effect was intercourse with two of the largest and times magnified. The effects produced by frequently and obviously exhibited in the exmost varied mechanical establishments in the passing engines and trains were mi- periments with the trains. In many cases, the kingdom, and have, during that time, nutely observed with this deflectometer; and the deflectometer showed only the common witnessed or superintended a vast number several instruments were provided, and amount of deflection when the engine (by of experiments and trials on various me- used at once, so as to show conveniently far the heaviest load) passed over; wherechanical subjects, many of which I have the effects produced on different parts of as, perhaps in the middle, or at the end of afterwards been enabled to examine in the the bar and its supports, by the passing of the train, a wagon would lurch over from works at large; I am therefore, to a certain the same load. Though some objections some irregularities, and throw up the index extent, acquainted with what theory gives, might be made to the manner in which it to double its former amount. This effect and what practice requires, and the limits was used, and, consequently, to the argu- was very particularly noticed by the depuit prescribes; so I am also with the views ments for rendering its indications compara-tation, Directors, Proprietors, and other and arguments of practical men, who I ble with those of former experiments, it is parties present. It follows, therefore, that know sometimes, like other persons, in their certain that it has already furnished im- till greater perfection can be obtained in anxiety to avoid one evil lose sight of other portant data, and that it will become one of railways, a strength of bar more than doucollateral evils, which their remedy in the most indispensable instruments to the ble that due to the mean strain must be procreases or creates; but I must say that I railway engineer. Its first trial produced never saw this so strongly marked as on the following lesson for railway managers, the present occasion, nor such a diversity of which surely will not be lost upon them :conflicting opinions on what appears so "Our first experiments were only tentasimple and plaina case. This is a circum-tive, with a view to try the instrument, but stance much to be regretted, not only as regards the doubts which it naturally throws upon the mind of proprietors, embarking large amounts of capital in the undertaking, but also in respect to practical even in these much was very distinctly In vided. 66 be expected to ensure, a less strength would ||It was then put into the press, and the trains ||would admit a plain single Trail; but, as be sufficient; or rather, allowing the same brought on as usual, under the superinten- the rail he decidedly recommends has a strength, an engine of 14 or 16 tons might dence of Mr. Edward Woods and Mr. John bottom flanch, it is proposed, that, where be passed over with the greatest confidence. Gray; Mr. Locke himself being obliged to the blocks fall, a protuberance shall be left By referring to the observed results in leave just at the time the experiment was on the middle rib, so as to fill up its thickthe Appendix, it will be seen, that one rail in progress. ness to a level with the perpendicular face is sometimes depressed by one wheel a "Mr. Rathbone, Mr. Edward Cropper, of the bottom flanch. A rail is thus obtainquarter of an inch, while the other wheel is and myself, were also present, and the re-ed which admits the use of a plain chair; perhaps on a block; and immediately after sult was, that the bar thus mutilated showed but the adaptation of particular spots to the the high wheel is depressed, and the lower greater strength than the mean strength chair seems to bring on the same difficulty wheel raised, giving thus a rocking motion which Mr. Locke found to belong to it when with respect to the placing of the blocks to the carriages, the effect of which was ren- whole. Now, although I am ready to grant opposite to each other, as was found in the dered remarkably obvious by the little in- that the bar was actually weakened, and case of the fish-bellied rail. It seems posstrument employed. No doubt much of that this apparent anomaly is attributable to sible to avoid it in either case by making this is due to a want of parallelism in the the imperfection of the press, yet, on the the bearing places half an inch longer than bearing blocks; and therefore, as one step other hand, it must be admitted that it could, the width of the chair. The reason given towards correction, I would recommend it with such a result, have lost but little of its by some for preferring the fish-bellied rail, to be made a special instruction, that the strength, and that the iron thus abstracted, "that its weak neck allows it to follow a blocks shall in every case be placed immedi- viz. nearly of the whole section, if judi- sinking chair," is certainly a curious speciately opposite to each other, which, in pa- ciously introduced elsewhere, would un- men of engineering sagacity. The further rallel rails, may always be effected without doubtedly give a much stronger rail." observations on the best form of chair deexpense or inconvenience. Other correcserve careful attention. tions, however, are necessary, which will be noticed in their proper places." The section on "the formation of the joints" opens very curiously: While we fully admit the importance of these remarks, we imagine they will require further illustration before they obtain geneAnother branch of the subject is the ral assent. What is the longitudinal form "On carefully examining the joints of length of bearing, and the consequent inqui- assumed by the extreme lateral fibres sup- the rails on the Liverpool and Manchester ries as to the sectional dimensions of the posed to be so nearly ineffectual? If it be line, I am disposed to estimate that about rail and stability of the blocks and chairs. the same as that of their neighbor fibres to-one in six of the plain butt joints are as perAdopting the parallel rail, and rejecting the ward the centre, it has required force to ex- fect as can well be desired, and that another double-headed one, Professor Barlow deter- tend them-if it be nearer a straight line, one in six are as bad as bad workmanship mines from experience that the head of the they have hindered to some amount the ex- and negligence can make them; the rerail ought not to have a less sectional area tension of their fellows. Mr. Barlow does maining two thirds varying in character bethan 24 inches, that is, it should not weigh not hazard opinions lightly, and will proba- tween these two extremes." less than 22 lbs. per yard, and that the en-bly, on some future occasion, give further tire depth must not exceed 5 inches. Com- reasons for the conclusion at which he has mencing with these assumptions, he gives plans, computations, and tables for rails with bearings of the lengths of 3 feet, 3 feet 9 inches, 4, 5, and 6 feet, the sections being so arranged as to give the maximum strength. In discussing the best sectional form of rail, Mr. Barlow makes an observation well worthy of remark :— arrived. Has this celebrated road produced its splendid effects, while one half of its power has been wasted, and its cost of repair doubled by bad "workmanship and negligence?" What may not be hoped for when searching inquiries like the present shall have brought up railway furniture even to the present standard of decent workmanship? After urging the necessity and attainableness of much greater accuracy, and stating that government work is much better done, the report proceeds In testing the stability of the blocks, the deflectometer again did good service. Though no great exactness was attained, it appeared that blocks, five feet asunder, sunk as little under a passing load as those but three feet apart. Considerable difference of opinion seems to exist, as to the economy and propriety on other grounds, of the "In the sections given in a preceding use of more or fewer blocks. The argupage for rails at different lengths of bear-ments on both sides are given; some of ings, it will be seen that I have confined the which seem to show that the Professor's "In the smaller shells, which are still breadth of the lower web to 14, or, at most, help was by no means superfluous. He considerably larger than the opening in a to 13, inches, and this has been done, al-gives his own opinion in these words :- railway chair, and unquestionably much though I am well aware that, to extend the "The conclusion to which I am brought, more difficult to cast, not more than a debreadth of the lower web, and to reduce its as to the relative expense of maintenance viation of th of an inch is allowed, and depth, would theoretically give the strongest per block in five feet and three feet bear-I can see no reason why the railway chairs rail; in fact that the double T is, on paper, ings, or, more generally, in long and short and the end of the rails, should not be suba stronger rail than the deep and less broad bearings, after well weighing all these points, mitted to at least as close a gauge. To flanched rail, but I am quite convinced it is is, first, that in embankments, and where enforce this accuracy, may perhaps incur not so in practice. The lower web comes there is a soft sub-soil, the expense would some present charge, but do not the wear no other way into use than as it is brought be greater at first with the long bearings and tear of the rails and engines incur a into a state of tension by the action of the than with the short, but that it would ulti-much larger constant expense of maintecentre rib; and although the fibres of the mately become the same, although certainly nance? I am sure it is unnecessary for me lower web lying immediately below the cen- never less; and, secondly, that on rocky, to urge this point upon those proprietors tre rib are brought into action by it, and or very solid bottoms, the expense would who witnessed, during the experiments, the that these fibres excite a similar action la- be very nearly the same from first to last." concussion on the rail exhibited by the deterally in those immediately contiguous to It can scarcely be doubted, that, while flectomer, which, of course, produced a them, and these again to the next, and so the earthern surface on which the block light concussion on the engine and carriaon, yet in a ductile metal, like malleable rests is new, it will be a little compressed ges. The whole of these were, doubtless, iron, this lateral effect is soon lost; so that permanently by every blow, and the number due to irregularities, of which the want of the extreme fibres of the extended lower of blows being as the distance between parallelism of the blocks and bad joints flanch become inefficient. block and block, it will be sooner compress- were the principal. Some persons present "To convince Mr. Locke and some oth-ed under long than short bearings; but, as attributed them in part to flat places in the er gentlemen of the weakness of the double soon as it has become so hard as to return wheel; but if there are flat places in the T form, I had one of the rails taken up, to its shape after the greatest blows to which circumference of the wheel, to what are these and an inch cut away on each side from it is liable, it is of little importance how of attributable but to bad joints? To be conthe lower flanch, reducing its breadth at the ten it is struck; that is, whether the bear-vinced of this we have only to consider point of greatest strain, that is, in the mid- ings be long or short. what must be the effect of a blow on a wheel dle of the bar, to 14 instead of 24 inches. The form of chair he prefers is one which supporting a load of 3 tons, and moving "In order to arrive at some estimate of this effect, a bad or open joint was select ed, the deflectometer applied to the block, and the shock measured by the instrument. The rail was then taken up and relaid, so as to make the joint as close as usual, leaving the opening at the other end, and the effect was again taken, when it was found that the bad joint increased the force of concussion full 50 per cent.; that is, the engine had to sustain a shock from this circumstance one-half at least greater than was due to a very common joint, and probably double what it would have had to sustain at a good one." with a velocity of 30 or 32 miles per hour, || dimensions of the rails and chairs, and versed by a locomotive engine, and its train when such a body meets the end of a rail greater attention paid to the parallelism of of a gross weight of one hundred tongrising, or, perhaps, nearly of an inch the blocks, and to a proper adjustment of the The experience of the Liverpool and Man-above another; or when the joints are so distances of the ends of the rails from each chester Railway has shown that the average open as to allow the wheel to fall from one other to allow for expansion and contraction." consumption of coke is considerably less upon the other, with all the impetus due to Some important theoretical investigations than half a pound per ton for each mile it such velocity. follow the Report, which we cannot notice is carried on a railway; but taking the conat present, further than to extract two im-sumption at half a pound, the whole weightTM portant conclusions. of one hundred tons will require the conIt is found, "that the sum of all the va-sumption of 50 lbs. of coke. It may be: riable resistances to a load by the deflection calculated that every 10 lbs. of coke will of the bar over which it passes, is exactly evaporate a cubic foot of water; so that half the resistance the load would experi- the whole 50 lbs. will convert into steam 5 ence in ascending a plane of the same half cubic feet of water in the distance of 1 length, and whose height is equal to the mile. Now to convert into steam 1 cubic central deflection of the same bar." foot of water, requires 1,950, or say 2,000 cubic feet of air, then 5 feet of water will of course require 10,000 feet; and this will be the whole amount of contaminated air in one mile in length of tunnel. To deter mine the proportion of such an amount of foul air, and the whole air contained in the tunnel, we may take for example a moderate sized tunnel 30 feet high, and having an area of 800 feet. One mile in length of such a tunnel will contain 4,224,000 cubic feet; hence the contaminated air will bear to the whole quantity in the tunnel the ratio of 10,000 to 4,224,000; or it will be as l' to 422. It will scarcely after this appear that any valid objection to turnels, to assert that an injurious effect must result from the contaminated air, when we find that the quantity of this description of air, produced by the passing of the whole train, will be no more than part of the whole quantity in the tunnel. From the table-page 88, it seems that the increase of power required by the deflections of the bars, is nearly proportionate to the distance of the blocks; a fact which is certainly to be taken into account when determining the length of bearing. Thus we may add, that the same care The appendix details many experiments which is required by the "scarcely-percop-not given in the body of the Report. tible" but important curve in the bottom of Mr. Locke's chairs (p. 55) would certainly produce much better articles than those described as in use on the Liverpool and Manchester line. The following is the summary which the Professor gives of his Report: "3d. I am of opinion that the cost of maintenance will, in the former case, after a short time, be in proportion to the reduced number of blocks, but certainly not less. RAILWAY TUNNELS. Lines for a Brighton Railway) DEPTH OF MINES. The whole forms a very valuable contribution to our knowledge on some of the most important subjects connected with the construction and management of railways. We cannot but hope, that the same profound mathematician and veteran experimentalist will be again engaged, in illustrating the "1st. I am of opinion, that as far as is theory and correcting the practice of this consistent with the amount of the first out-most influential of recent inventions. lay, it is desirable to increase the weight or section of the rails, and to decrease proportionally the number of bearing blocks.(From Mr Gibb's Report upon the several proposed "2d. That in cuttings and other places furnishing a good firm bearing, the present An objection has been made generally Let us then venture to hope, that any size of blocks is sufficient; viz. allowing to all tunnels-namely, that the air con- prejudices which may now exist against the for the intermediate blocks four feet, and tained in them will be so contaminated by construction of tunnels upon railways will for joint blocks five feet, while the bearing the noxious gas produced by the locomo- be dispelled, when we find that no injurious length does not exceed five feet; but that tive engines in passing through them, as to consequences will ever result from the foul on embankments they will probably require render it unfit for respiration. Whether air, or any other of the numerous evils which to be proportionally increased in size. But this objection has ever been advanced, or have been so forcibly dwelt upon by those I recommend this to be put to the test of at all supported, by any scientific man pos- who affect to perceive the most unhappy actual experiment. sessing sufficient chemical knowledge to consequences from their adoption.-[Lonenable him to judge correctly on the sub- don Mechanics' Magazine.] ject, is doubtful. The probability, however, is, that the fear of any injurious effects from foul air has originated in those who "4th. I consider the double and equal have witnessed the effects produced by flanched rail to be inferior, in strength and steam engines in passing through the small convenience of fixing, to that which is de- tunnels on some of our canals; and if they scribed and modified to suit different dis- have for a moment imagined that any simtances, in a preceding page. ilarity will be found in the effects in the "5th. I consider Mr. Sinclair's proposi-two cases, their fears are quite justifiable. tion for rendering the rail plane at its points The tunnels on canals are commonly conof bearing, to be in every respect recom- structed of such limited dimensions, that it mendable. would be highly dangerous to attempt the "6th. I am of opinion the form of chair, same application of steam power as will be and method of fixing the rail in the chair, necessary on a railway; for instance, in The deep mines in the Tyrol, Hartz and proposed by Mr. Stephenson, is as simple the tunnel constructed by Mr. Telford; on Andes, above described, are all in high sitand efficient (adopting the plan of rolling the Hare Castle Canal, the area above the uations-the bottom of the Mexican mine of Mr. Sinclair) as can be desired. water in the canal is only about one hun- is six thousand feet higher than the top of “7th. Yielding, as I am always ready to dred feet; and even the Thames and Med-the Cornwall shaft. The deepest perforado, to practical opinions, when they are way in transverse dimensions, perhaps the tion beneath the level of the sea, and confound pretty generally to agree, I am dis-largest canal tunnel in England, has only sequently the nearest approach to the earth's posed to think the present mode of fixing an area of four hundred and fifty feet; while centre, has been made at the Monkwearthe chairs to the blocks, with a wooden the smallest tunnel contemplated on the mouth colliery, which is fifteen hundred and plug and iron pin, is, from its simplicity Brighton Railway, will have an area of at thirteen feet below the surface of the Ger and convenience, the most recommendable. least six hundred feet. man ocean. Pearce's shaft (thirteen hundred and thirty-eight feet below the level of the sea,) was, until lately, the deepest in the world.[Geology in 1835, (Mining Kits puhl copper mine in the Tyrol Feet. mountains, Sampson mine at Andreasberg, in the Hartz, Valencia mine, (silver,) Guanaxuato, Pearce's shaft, (copper,) consolidated "Lastly. I am strongly convinced that In order to explain to what extent the air no change or modification of form will pro- in a tunnel is contaminated by a locomoduce any essential improvement, till greater tive engine passing through it, let us supuniformity be enforced in the figure and pose a tunnel one mile in length to be tra- Review.)] 2764 2230 2170 1650 1600 1410 1380 |