in gross 0. in. tons A PRACTICAL TABLE OF THE EFFECTS OF THE LEAD: proper to the engine, that may either favor or impede its effect. We have still to ex• Load amine two external circumstances that may DESCRIPTION OF THE ENGINE. tons, have a similar influence on the motions. The curves offer on the railways an ad1 in. ditional resistance, which is so much the miles. miles. miles. miles. greater according as the degree of their inEngine with cylinders 11 in. or 0.917 ft. 50 31.0231.52 32.51 | 34.23 curvation is more considerable. Stroke 16 in. or . 1.33 ft. 100 21.68 | 22.02 22.72 23.92 The wagons being of a square form, tend Wheel. • 5 ft. 141 17.39 17.66 18.22 | 19.18 to continue their motion in a straight line. Friction · 120 lbs. 155 16.28 | 16.54 | 17.06 0. If, therefore, they are obliged to follow a Heating surface - 140 sq. ft. 163 15.72 | 15.96 0. 0. curve, the flange of the wheel does no longer Effective pressure in boiler - 50 lbs. 165 15.58 0. 0. 0. pass in a tangent along the rail without Range of the slide . 3 in. touching it, as it does in a direct motion. Lap over the appertures The rail, on the contrary, presents itself partially crosswise before the wheel, and Engine with cylinders 12 in. or 1 ft. 50 27.80 28.24 | 29.13 30.68 opposes thus its progress, by forcing it to Stroke 16 in. or 1.33 ft. 100 20.05 20.37 21.01 22.12 deviate constantly from its direction. Wheel • 5 ft. 150 15.68 | 15.93 | 16.43 | 17.30 Moreover, the wheel that follows the exFriction 150 lbs. 168 14.56 | 14.79 15.25 | 16.06 terior rail of the curve has naturally more Heating surface 140 sq. ft. 183 13.72 | 13.94 14.38 0. way to travel than that which follows the inEffective pressure in boiler · 50 lbs. 193 13.22 13.43 0. 0. terior rail. Now in the wagons at present Range of the slide 3 in. in use, the two wheels of the same pair are Lap over the apertures not independent of one another. They are fixed on the axletree that turns with them. Engine with cylinders 13 in. or 1.083 ft. 50 29.03 29.49 | 30.42 | 32.03 If therefore the road travelled by one of the Stroke 16 in. or 1.33 ft. two wheels be less than that of the other, Wheel • 5 ft. 150 the latter one must necessarily be dragged Friction · 165 lbs. 197 14.25 14.47 | 14.93 15.72 Heating surface along without turning on the difference of - 160 sq. ft. 216 13.37 13.58 | 14.01 0. the two roads. Effective pressure in boiler · 50 lbs. 227 12.91 13.11 0. 0. Range of the slide Finally, on passing the curves, the wag3 in. 231 12.75 0. 0. Lap over the apertures ons are thrown by the centrifugal force of i in. the motion against the outward rail, the reEngine with cylinders 14 in, or 1.116 fi. sult of which is a lateral friction of the flange 50 29.83 30.30 | 31.26 32.91 Stroke 16 in. or - 1.33 ft. of the wheel against the rail, which does not 100 22.56 22.92 23.64 21.89 Wheel exist in the direct motion. - 5 ft. 150 18.14 | 12.43 | 19.00 20.01 Friction 180 lbs. 200 15.17 15.41 It is impossible to constặuct the wheels 15.89 16.73 Heating surface - 180 sq.ft. of the wagons and the railway itself in 229 13.85 14.07 | 14.51 15.28 Effective pressure in boiler 50 lbs. such a manner that these three additional 252 12.96 13.16 | 13.58 0. Range of the slide . 3 in. causes of resistance may be destroyed. 0. 0. Lap over the apprtures · in. The mode we are going to describe, in order to obtain that effect, is that which is already Engine with cylinders 12 in. or 1 ft. 50 26.16 26.57 | 27.41 28.86 known ; viz., the conicalness of the tire of Stoke 18 in. or · 1.50 ft. 100 19.85 20.16 20.50 21.90 the wheel, and a greater elevation of the Wheel. • 5 ft. 150 outward rail at the place of the curve. But Friction . 165 lbs. 198 13.93 14.15 14.60 | 15.37 those means have until now been employed Heating surface - 160 sq.ft. only by approximation, and fulfil more or Effective presssure in boiler 50 lbs. 217 12.69 12.89 0. 0. less imperfectly the intended purpose. By Range of the slide - 3 in. sumitting them to calculation, we trust we Lap over the apertures .& in. shall be able to deduce general rules, which will make us certain that the required effect From these results we see that too great exccentric in that position. This operation will be cbtained. a lead detracts a considerable portion from concluded, it is clear that whenever the The particular resistance owing to the the power of the engine. It is therefore crank is horizontal , or the piston ready to passage of the curves, is composed of two necessary not to exceed, in that respect, begin its stroke, the slide will open the pas distinct parts, as to their causes and their efcertain limits. sage to the degree required. fects. It is, besides, easy to know the lead, or There are some ways of altering the The first, according to what we have to regulate it at any degree. lead without opening each time the chimney seen above, is occasioned by the waggons After having opened the chamber situated chamber ; but they are not quite exact, and being obliged to turn along the curve, which under the chimney, and taken off the top of some of them are injurious to the engine. produces an opposition of the rail to the the slide-box, in order to see the slides In the experiments we have related above motion, and a dragging of the wheel. work, the engine must be pushed gently on the velocity of the load of the engines, The second is owing to the centrifugal forward on the rails, until the crank of the the Vesla engine was the only one in which force, and produces the friction of the axle be perfectly horizontal. the lead was considerable enough to have a flange of the wheel against the rail. Then the piston is at the bottom of the remarkable effect on the speed. The first of these two resistances will cylinder. If at that moment the passages evidently be corrected, if we succeed in which the slide opens to the steam be meas CHAPTER VII. constructing the wheels of the wagon in ured, it will give exactly the lead. AND INCLINED Planes. such a manner that the wagon may follow If we wish to alter the lead, we keep the of itself the curve of the railway. For that, crank in the same position, and looseng ARTICLE I. it will be sufficient to make the wheel slightly the driver which is fastened to the axle only conical with its greatest diameter inside ; with a screw, we turn the exccentric, until $ 1. Of the conical form of the TWheels and that is to say, towards the body of the wagthe slide, which moves at the same time, sur plus of eleration of the Rails, calcula-||on, as appears on the engine in fig. 2. opens the passage as much as is wanted. ted to annul the effect of the Curves. By that disposition, when the centrifugal Then we replace the driver so as to fix the We have considered the dispositions force throws the wagon on the outside of or THE CURVES or TIIE CURVES, 2 a 1 the curve, the wheel on that same side willl Our intention being to produce that effect, In this expression, g is the accelerating then rest on a tire of a larger diameter. Two by pushing the wagon aside on the road,|| force of gravitation, or the double of the effects will result from this. The wagon | the question is, how much the wagon must space pas:ed cver in the unit of time by a will no longer tend to follow a straight line. be laterally displaced. body falling in a vacuum. Taking a seOne of its wheels growing larger than the This point depends evidently on the de-cond for the unit of time, and a foot for the other, will, on the contrary, have a tendency gree of conicalness of the wheel. unit of space, we have g=32. Referring to turn in the direction of the curve. Be At Liverpool, the wheels of the wagons to the same units the velocity V, and the sides which, the two coupled wheels will have 3 ft. diarneter at the interior part or radius of curvation 1, we shall have the naturally travel different lengths of road near the flange, and 2 ft. 11 in. at the ex measure of the centrifugal force expressed without any dragging on the rail. terior part. The wheel is originally cylin-| by its proportion to the weight P, or repre. This form of the wheel and its effects be-drical, but the conical form is produced by sented by a weight. ing very well understood, we have first to the addition of a second tire, the breadth of Let us suppose, for instance, that the vedetermine what difference of diameter must which, not including the flange, is } in. less locity of the motion be 20 miles an hour, or be created between the two wheels, in order on one side than on the other. Fig. 29, 29.3 fi. per second, and the radius of the that the wagon may turn of itself with the represents the section of that tire on a scale curve 500 ft. ; we shall have curve, and how much the wagon must de- of £. Its breadth being 34 in., we see that 29.3 viate on one side in order to produce that its conical inclination is in. on 3} in. or - f=Px 1 P. differe ce of diameter. Then we shall 32 X 500 Let us suppose in general the inclination see how the railway must be constructed, |of the tire expressed by 1 So in that case the centrifugal force will The two wheels in order that the centrifugal force of the be the nineteenth part of the weight of the motion produce of itself that lateral devia-| running originally upon equal tires, in order body in motion. tion. It will thus be clear, that, those dif-Ithat the difference D-D' be produced in The sense of the signs being now well ferent conditions being fulfilled, the first their diameters, by the displacing of the understood, we return to the general expresspecies of resistance of the curve will be tire on the rail, this lateral displacing of the sion of the centrifugal force. destroyed by the motion itself. Coming to wheel must evidently be V? the friction of the flange of the wheel against f=P the rail, we shall determine what degree of a (D-D'); conicalness thie wheel must have, in order for the inclination of the tire being this The effort of this force exerting itself in that, even in passing over the most abrupt the direction of the radius, its effect will be curve of the railway, the lateral deviation displacing will produce on the thickness to push all the wagons out of the curve. If of the wagon may never go so far as to of the tire, or on the radius of the wheel, the two sides of the railway are of equal put the fange in contact with the side of the a difference of elevation, the wagons will be stopped in the rail. In this way, both by the disposition of (D-D'), But the rails and by the form of the wheels, the which will make on the diameter Hange of the wheel against the rail. two species of resistance will be destroyed. }(D-D'). if we give to the outward rail a surplus of Let us suppose that mm' and nn' (tig. This difference on the diameter will be pro elevation above the inward one, it is clear 28) be the two lines of rails of the way. Induced in plus on the outside wheel, and as that, in increasing sufficiently that elevaorder that the wagon inay follow without an equul difference, but in a contrary sense, tion, we shall be able to master at last the centrifugal in such a manner as to effort the curve of the way, it is necessary that is to say, in minus, will be produced that, while the outside wheels describes the on the inside wheel; the result will be a permit it only to produce just the displacing arc min', the inside wheel describes of itself total difference of D) - D' between the ac we want. In fact, by raising in that manthe arc ni', which terminati s at the same ra- tual diameter of the two wheels, as we rer the outward side, we change the rail. dius as the first. If, therefore, the length! have said. way in an inclined plane. The wagons mm' represent a circumference of the outside Thus the lateral motion to be produced is placed on that plane ought, by virtue of wheel, nn' must also be a circumference of a eD their gravity, to slip towards the lower rail. the in-ide wheel, and the diameters of the | a(D–D)=2(rte) On the other hand, the centrifugal force two wheels must be in a certain proportion We know at present what must be the is the highest. We create, then, by that pushes them against the outward rail, which for that effect to be produced. lateral displacing of the wagon, in order to means, a counterpoise to the centrifugal Let I be the diameter of the first wheel, destroy the first species of resistance. force, and D' that of the second, - being the ratio The question now is, to make use of the of the cireumference to the diameter, we centrifugal force to produce that effect. Let us call y the surplus of elevation 'shall have It is its natural tendency ; but it is evident given to the outward rail (fig. 30); 2e bemm' =D, and itu'==D'. that that force must produce exactly the ing the breadth of the way, the inclination Now the two arcs being both terminated by necessary displacing, else the defect would of the plane on which the wagons are the same radius, we haveby no means be corrected. On this plane, the gravity If we represent by r the radius of cur 2e nn' vation, by V the velocity of the motion, and of a body, the weight of which is P, is ex. by m the mass of the body moved, the cen-pressed by If we express the radius of curvation of by trifugal force produced on the curve will r, and the half breadth of the road by e, this be, as is known, expressed by 2e proportion may be expressed thus : V: This gravity, as we have seen, tends to inm' f=m rte make the wagons fall within the curve, ; nal But P being the weight of that same while the centritugal force pushes it withthen, body, and g the accelerating force of gravi-out. If, therefore, we select the height y, Dgte tation, we have such as may give ya 2e the train, in passing over the curve, will exD-D'=D 2 D PV? fa perience no derangement from its original r-te re position, because the gravity and the cenThis equation shows the difference that which is the expression of the centrifugal trifugal force will equilibrate. must exist between the diameters of the force of a body of a given weight P, mov But, as for motives already explained, wheels, that the required effect may be ob-ing with a velocity V, on a curve the radius we require the wagon to be pushed aside, tained. of curvation of which is r. a certain quantity expressed by placed, is y. mm' mo no PX Y. Рxy = P x -e 2e eV: aᎠ eD For instance, on a line, the most abrupt y = 2 2 (r + e) gr 2 (r+ curve of which has 500 ft. radius, with we must endeavor to find out what is the Knowing, then, the conical form and the wagons having wheels of 3 ft. diameter, and a play of 1 in. on each side of the way. the necessary inclination. diameter of the wheels, as well as the ave equation shows that the least inclination one Let us then suppose the train already | rage velocity of the motion and the breadth ought to give to the tire of wheel is ta; but displaced as much as required. Let us of the way, this expression will give the sur a more considerable inclination will answer, imagine, for instance, that the train has plus of elevation y that suits the radius of a fortiori. been pushed from the position ab to the curvation r. On the Liverpool and Manchester Railpiston cd (fig. 30 ;) that is to say, that the Let us suppose that we have to employ way, the most abrupt curve, which is the point of the inside wheel that was at a be the dimensions of the railway and wagons one at the entrance of Manchester, has a -come to c, at the distance pe from the first of Liverpool; that is to say, that we have: || radius of 858 ft. This results a conical inpoint, and that at the same tiine, the point V, average velocity, 20 miles an hour, orclination of ', and this would answer in all of the outward wheel that was at b, be 29.3ft. per. second. cases ; but having said that a greater inclicome to d. In this situation, the inclina 1 tion of the plane on which the train is, will inclination of the tire of the whcel, 1. to adopt a greater inclination, if it suits nation will fulfil the same object, we are free be y e, half breadth of the way, 2.35 ft. other purposes better. D, diameter of the wheel at its right It is customary to give an inclination of Moreover, the conical inclination of the place on the rail, 3 ft. 4. The motive for making it so considerawheels shows that on the outward side of If we wish to construct on that railway a rubbing against the rail , either in case of a ble, is to prevent all possibility of the flange the curve the wheel will have increased its diameter by a certain quantity, in conse curve of 500 ft. radius, on which the wag: | strong side-wind, or in case of some fortuquence of the lateral deviation ; while on the ons may experience no additional resist itous defect in the level of the rails, by imterior side, it will on the contrary, have ance the equation will give which the wagons would be thrown on the diminished of an equal quantity. The tire of y 0.236 ft, or in inches, y= 2.83 in. lower rail. Having seen above that, with the wheel having a supposed inclination of We must, therefore, for that curve, with an inclination of ', there would be no dan1 a lateral motion represented by M, that wheel and that average velocity, give a ger of the flange rubbing in the curves, that surplus of elevation of 2.83 in. to the out- || danger will be still more impossible with must have produced on each wheel a differ- ward rail. an inclination of .. We conclude that, with wheels having ence in height represented by .. The ef Adopting the surplus of elevation of the rail deduced from that equation, we render that inclination, the surplus of elevation of fect of that variation of the wheels being it impossible, the first species of resist. I will correct the first species of resistance of the rail which we have determined above, to incline the wagon on one side, so that it ance, which the passage of the curves tend the curves without creating the second, and is raised on one side of the quantity to produce. However, as we only destroy that, that resistance by a certain lateral deviation consequently, the train will pass over the curves without any diminution of speed. and lowered on the other of the same of the wagon, it might be feared that that deviation might go so far as to make the quantity '; the result is a total inclina- flange of the wheel rub against the rail, in||$ 2, A Practical Table of the. Surplus of which case we would only have substituted Elevation of the outward Rail in Curves, 24 tion of which must thus be added to one resistance for another. This is, there in order to annul the effects of those fore, the point we have still to consider. Curves. the inclination already produced by the difference of level between the rails. We have, until now, supposed the incli. From what has been said, the surplus of Consequently the outward side of the nation of the tire of the wheel to be || Pailin the curves, is determined by the fo!loxwagon will be raised above the interior side of a quantity equal to yt given a priori. But as it is on that incli- ing formulæ: eV? aD eD Y { the wagon must undergo on the rails, it 2 irte) rte the base which separates the two bearing must evidently be such that, even on the points is measured by 2e —M, the final re- most abrupt curve of the line, the lateral In this equation the signs have the followsult is that the wagon will be in the same deviation of the wagon may never be con ing value: case as if it were placed on a plane, the in-siderable enough to bring the flange of the D, diameter of the wheel expressed in clination of which should be wheel in contact with the rail. feet. 1, radius of the curve expressed in the sary lateral deviation is expressed by e, half of the width of the way expressed 2e aed in the same. In order that the centrifugal force may, therefore, the wagons have, for instance, 2(x + e) V, average velocity that is to be given to maint in the wagon in that position without the motion, expressed in feet per secthrowing it out or letting it fall in, that is to a play of 2 in. on the way altogether; that ond. say, so that there may be an equilibrium be- is to say, if, in their regular position, the g, accelerating force of gravitation, extween the gravity on the plane and the cen flanges of the wheels keep on each side at pressed in feet per second, or g=32 feet. trifugal force, we must have est value of the deviation M, must always be ; consequently, a= 7. less than 1 in. By that greatest value of u, y, surplus of elevation to be given to the outward rail of the curve, over the infor r the radius of that curve, and for uits ward rail, expressed in feet and deci inals of feet. will give the greatest value that can be given Solving these formulæ in the most usual to the quantity a, or the least value of the in-cases on railways, we make out the followSubstituting for u its value, this equation 1 clination ing table which dispenses with all calculabecomes tions in that respect. 2 y + same manner. a 1 1 a 7 y+ Х or in. 990 in. 30 miles. hour, being 20 miles. 10 miles. in. ELEVATION TO BE GIVEN TO THE OUTWARD RAIL IN THE CURVES, IN ORDER TO ANNUL THE RETARDING EFFECT OF THE CURVES. A PRACTICAL TABLE OF THE SURPLUS 250 Designation of the Wagons and the Way. 0.083 ft. 3 ft. 1 in., or present the resistance that would be offered/jare helped in passing the plane by an enby a load of 308 t. on a level. Consegine stationed at the foot of the acclivity, quently the engine which, before, drew 100 and especially intended for that use. This t. must now draw 408 t., or at least must engine is, consequently, constructed for a exert the same effort as if it drew 408 t. slow motion and a considerable power. on a level. The cylinders have 12 or 14 in. diameter, This is the manner in which the calcu-l with the usual stroke of 16 in., and the lation of the resistance on inclined planes | wheels have only 4 fi. 6 in. Besides, in must be established; and we have entered order to have more adhesion, the weight of into those particulars, because it frequenily he engine is 12 t. and the four wheels are happens that, in making the calculation, coupled. These additional engines, workthe gravity of the load is alone considered, ing less than the others, require also, in without taking into accouni the gravity of general, much less repairs. the engine, which ought also to enter for On the Darlington Railway, the accli. its share. vities are much too numerous for an ad In speaking of the fuel, we shall sce that liional engine to be placed at each of the inclined planes of the Liverpool Rail || them. The load of the engine must there. way, which at first sigit appear quite in fore be limited so that it may ascend with significant, oblige, however, ihe engines to that load the most inclined of the planes. il surplus of work, which amounis 10 a The locomotive engines acquire, howsixth part of what ihey would have to do ever, a considerable augmentation of power, on a level. By this we see how important at the moment of their passage on an init is, in establishing a railway, to keep it clined plane, because their speed being on as perfect a level as possible. It fre- suddenly considerably reduced, the cylinquen:ly happens that, by avoiding to level ders consume a smaller quantity of steam. a part of the road, that is to say, 10 cut|The fire, strongly excited by the preceding through a hill, or to form an erobankment rapidity of the engine, continuing to furthrough a valley, a great economy is ex-nish the same quantity of steam, a great pected. This is, however, a great mis- part of it must escape through the valve. ake, for, in most instances, the only eco-But the passage of the valve is too narrow noiny is that of the first outlay, whereas, to emit freely all that steam. Besides, the the annual ang mentation of expense sur-spring that presses on the valve opposes passes by far the interest of the capital more and more resistance, in proportion as saved; so that, instead of an economy, we the steam tends to raise it higher, in order have in reality a greater expense. This to get a wider passage for itself. The conadditional expense may even, in some sequence is that the steam, not being able ARTICLE II. cases, go so far as to paralyze completely | to escape as quickly as it is generated, all the advantages of the undertaking suffers an increase of pressure in the boiler. In suffering inclined planes to subsist on This increase of pressure evidently de§ 1. Of the Resistance of the Trains on a line of railway, it not only becomes iin-pends on several circumstances: the size Inclined Planes. possible to lower sufficiently the freight of of the valve, the evaporating power of the the goods ; but, what is much more im-boiler, the previous excitation of the fire, Inclined planes are a great obstacle toportant, frequent accidents occur while des- and finally the length of the lever at the the motion on railways. cending those steep acclivities, the least exiremity of which the spring-balance acts. As soon as the trains reach these in-inconvenience of which is to destroy pu- In some engines this increase may amount clined planes, they offer a considerable sur-| blic confidence in the safety of the con to 10 lbs. per square inch, as we have replus of resistance, on account of the gra- veyance. It is, therefore, necessary to lay marked in speaking of the pressure. vity of ihe total mass that must be drawnown as a principle, that the end to be In that case, if the usual effective presup the plane. aimed at in the construction of a railway, I sure of the engine be 50 lbs. per square Let us suppose a train of 100 t. drawn is not only to make a smooth road, but inch, it may, on ascending the inclined by an engine. Having seen that on a level likewise a level one. It is, besides, the plane, increase 10 60 lhs., that is to say, in the friction of the wagons produces a re- || only way to apply with efficacy the use of the proportion of }, which is considerable. sistance of 8 lbs. per ton, the power re- locomotive engines. This must, therefore, he taken into account quired of the engine will be 800 lbs., when When, however, it has been impossible when it is required to calculate the load travelling on a level. But let us suppose to avoid the inclined planes, and when the the engines are able to draw on these the saine train ascending an inclined plane use of stationary engines has been rejected planes. But it is necessary to observe at too. On that plain, besides the resis- on account of the interruption they un-ihat this is effectual only when the intance owing to the friction of the wagons, avoidably cause in the service, there are clined planes are not of too considerable an a fresh resistance occurs, which is the gra- | only two ways that can be resorted 10. extent, because, in that case, the fire ceasvity of the total mass in motion on the The loads must either be regulated so thailing to be excited in the same proportion, plane. That gravity is the force by virtue they may not exceed the power of the en the surplus of effect will be reduced. The of which the train would roll back if it gine in going up the plane, or it is neces- weight of the engine must, besides, always were not retaineil; and it is equal to the sary to give the engines the help of one or give sufficient adhesion of the wheel to the weight of the mass divided by ihe number more others, according to what is required. rail, as we shall explain in the following that indicates the inclination of the plane. On the Liverpool Railway, the trains of Chapter. If, therefore, in this case, the load of 100 t. coaches never being very heavy, are seldom There is also another circumstance in is drawn by an engine weighing 10 t., the above the power of the engines on the which the engines are obliged to exert an total mass placed on the inclined plane will inost inclined parts of the line, viz. in the additional effort. That is at the moment be 110 t. or 246,400 lbs.; and thus its gra- two acclivities of go and go. In general, of starting. We have seen, in fact, ihat the vity on the inclined plane, at jów, will be therefore, the engines ascend these inclined power which, when the motion is once 2464 lbs. = 2,464 lbs. 'The surplus orplanes without help; and during the rest of created, need only to be constantly equal traction required of the engine, on ac-lhe trip, on the level or descending parts or to the resistance, must, on the contrary, count of that circumstance, is, therefore, the line, their speed is regulated by par- surpass it at the instant that it is to put 2,464 lbs., and, as we have seen that on a tially shutting the regulator. the mass in motion. The reason is plain : level 1 t. load is represented by 8 lbs. trac The trains that are too heavy for a single in the first place, it is only necessary to tion, we also see that those 2,464 lbs. re-engine, as are commonly those of wagons, || maintain the speed; in the other il must be OF THE INCLINED PLANES. A PRACTICAL TABLE OF THE RESISTANCE power itself, but in the fulcrum of the mo- der included, that is to say, 14 times their created and maintained. It is this addi-| elsewhere, or by its adhesion, as shall be|| helping engines, the work by the adhesion tional effort on the part of the moving mentioned in the following Chapter. of their four wheels, as has been said elsepower which is improperly called vis iner This table, assimilating the trains drawn where. The Atlas is the only one of ne tia, hecause it is attributed to a particular on inclined planes, to trains drawn on a former class that differs from the othersin resistance residing in the mass. level, gives the means to learn by the former that respect. This engine has six wheds, The starting is, therefore, a difficult task tables, either the loads the engines will be four of which are of equal size, and worled for a locomotive engine heavily loaded. able to draw on given inclinations, or, vice by the piston. The two others, whch However, at that moment the engine ac- rersa, the inclined planes the engines will are smaller, and have no flange, an quires, as well as on the inelined planes, be able to ascend with given loads. be raised out of contact with the rals, à considerable increase of power. Here by the action of the steam on a again the slowness of the motion produces CHAPTER VIII. moveable piston. That ingenious arrargetwo effects. The pressure in the cylinder OF THE ADHESION. ment, which may have more than one us:ful grows equal to the pressure in the boiler, application, in permitting the weight of an which is itself augmented by the effect of engine to be distributed upon six whels, the spring-balance. But, notwithstanding § 1. Measure of that Force. without making the engine more embarrissthis twofold advantage, the difficulty of The series of experiments we have de- ing than if it had only four, is due to Vir. starting still remains so great for consider- iscribed above on the velocity and load of J. Melling, of Liverpool, who, in this inable loads, that we should always advise the engines, solves also another question in stance, made use of it in order to give the giving in that point a slight declivity to regard to the motion of locomotive engines engine a much larger firebox, and corsethe way. By that means the trains woulul of which we have not yet spoken. That is quently the power of generating a greater be set in motion with more ease at the the adhesion of the wheel to the rails. quantity of steam. departure, and it would not be necessary We have remarked in describing the enat their arrival to inake use, in order to gine, that the power of the steam being ap- giving the measure of its effects; but the We have now expressed the adhesion by stop them, of the powerful brakes, theplied to the wheel, the engine is in the effect of which is certainly as destructive same situation as a carriage which is made power itself may be expressed in a direct manner. The load of 2-14 t. produced a reto the wheels of the wagons as to the to advance by pushing at the spokes. Thus, rails. as in that action, the only fulcrum of the Ibs.; the adhesion was thus equal at least sistance, or required a traction of 1,952 $ 2. Practical Table of the Resistance of wheel to the rail, if that adhesion is not suf- iurned without advancing. Now the ad moving power exists in the adhesion of the to 1,952 lbs., else the wheel woull bave the Trains on Inclined Planes. ficient, the force of the steam will indeed hering weight was 5.5 t. or expressed in In the preceding paragraph, we have seen make the wheels turn, but the wheels, but in what manner the resistance of the trains the wheels slipping on the rails instead of pounds 12,320 lbs.; we see then that the on the inclined planes must be calculated. adhering to them, will revolve, and the en- the adhering weight. Considering that force of adhesion was equal to about ; of The following table presents the result of gine will remain in the same place. that calculation in the cases which occur the The more considerable the train the en every 8 lbs. force corresponds wüh the most frequently on the railways. traction of a ton on a level, this expression is gine draws, the more power it must employ, exactly siunilar to the first. It is clear that, by the weights inscribed and the more resistance it must consequentin the following table, it is only intended to ly tind in the point on which it rests, for ex- and dirty, in consequence of damp weather, In winter when the rails are greasy show the resistance offered by the truin, and ecuting the motion. It was therefore to be not the weights the enç ines are able to draw, feared, that with considerable trains, the en the adhesion diminishes considerably :those weights being limited either by the gines would be unable to advance ; not that However, except in very extraordinary cirpower of the engine, as we have explained the force would be wanting in the moving to draw a load of 15 wagons, or 75 t., ten cumstances, the engines are always able tion. The experiments related above, establish adhering weight. In other words, the resisLoad in grossions which on the measure of that adhesion in the fine tance of 75 t. being 600 lbs., the force of adhesion is always at least o of the adherseason of the year. Ainong all these expe ing weight. Designation of sime resiziance the incli riments, not one is to be found where the the Enginu. nation of the plane being motion has been stopped or even slackened Adhesion being indispensable toihe creafor want of adhesion, and nevertheless we tion of a progressive motion, two conditions see loads that amount to more than 200 t. are necessary in order that an engine may If we take, for instance, the first experi draw il given load. 1st. That the dimen. Engine weigh44 4-5 | 7 87117 ment made with the Fury, on July 24; sions and proportions of the engine and its ing 3 1.... 210 131 15:212 ring a part of the journey, that engine drew boiler enable it to produce on the piston, by 75 12-13 1:3 191230 307 244 t. 100 151 1702011251 302 402 load, the adhesion must necessarily have The engine advancing with that means of the steam, the necessary pressure, which constitutes what is properly termed 125 200 218 219 311 373 197 | been sufhcient. Now the weight of the the power of the engine: and, 2nd, that the 150 (232 21238571145 532 Fury is 8.20 t, and that weight is divided weight of the engine be such as to give a. on . Engine weigh 25 45 50 55 71 91123in such a manner, that 5.5 t. are supported These two conditions of power and weight jug 10 t. 94 93107134162218 on the two hind wheels, which are the only I must be in concordance with each other; rable as itself. The result of this is, that much weight for the steam, that weight Engine weich 46 51 60 771 9512) and which consequently adheres by its whole ing 13t 75 124156 157 197239319 | own mass. $ 2. Of the Engines employed on Common 100 169 179 203 257 31041 Roads. On the The considerable loads that have been 175 250500350 431525 699 Liverpool Railway that disposition is gene- rawn by the engines in the experiments 200 319 319 393 197-96794|rally adopted for all trip engines, because described above, ought to remove the fears 225 359|39244055716681989 the adhesion of two wheels is sufficient for of such persons as suppose that the wheels 250 397'434 194 617 7401991|||the loads they have to draw. As for the of locomotive engines on railways are con OF THE TRAINS ON INCLINED PLAINS. a level would offer the Weight of the trains in gross tons, tender included 1 23 du 50 50 |