Part 4
“Fourthly, that the number of revolutions made by a carriage wheel depends on the size of that wheel, as well as on the motion of the vehicle. The fore wheels of the coaches which travel with the greatest expedition, revolve, on an average, about 100 times in a minute. One of the peculiar advantages of the method Mr. Vallance proposes, is, that it admits of the wheels of the vehicles which move in the cylinder being several times larger than the wheels of carriages which run on roads; owing to their being always kept in an exactly perpendicular position, and consequently free from the strain thrown on the spokes of a common carriage wheel, by the deflections from the perpendicular, which the nature of and obstructions upon roads continually occasion. Owing to this, the wheels of the vehicles which move in the proposed cylinder may be from ten to twelve feet in diameter; or nearly four times as large as the fore wheels of a coach. The same number of revolutions, therefore, which the fore wheel of a coach makes in an hour, would move the vehicle in the cylinder forty miles; and twice and a half that number of revolutions would give 100 miles an hour. Now if a common coach wheel which moves under the disadvantages of being constantly exposed to all the clogging and impediments arising from the dust and dirt of the road, can revolve for hours together at the rate of 100 times a minute, without being greased, excepting at the end of its journey of perhaps one hundred miles, it may fairly be presumed, that a wheel which would be not only free from all dust and dirt, but also moving in a reservoir of oil would revolve 250 times a minute without heating, even had we no such evidence as that referred to in page 36. But when that is taken into the consideration, all anxiety with reference to the effect a velocity of 100 miles an hour would have on the axes of the wheels, may be dismissed.
“Fifthly, nor is it necessary that any anxiety should be entertained, as to the effect such a velocity would have on respiration; for in addition to what is urged on this matter at pages 28, 29, and 35, I have to state that, though I was purposely exposed to the ‘vacuum’ as it is termed, many times during my examination of, and riding in the cylinder, yet I did not experience the least inconvenience from it. Indeed, I should not have been aware of it, had my attention not been directed to it; the degree of exhaustion necessary to move a carriage, not being much more than the ten-thousandth part of a vacuum: a diminution of density, which would not lower the barometer so much as the two-hundredth part of an inch.
“Sixthly, a degree of exhaustion, or vacuum, which is not sufficient visibly to affect the barometer, being enough to move the carriage with persons in it, so as for them to experience the effect, and fully comprehend the operation of the principle, it becomes evident that the idea at first entertained of a perfect vacuum being indispensable, is most erroneous; and the objections which at first present themselves to us, relative to the difficulty of constructing the cylinder—of making the joints air tight, and of so adapting the ends of the vehicle to the cylinder, as should prevent the passage of any important quantity of air, without occasioning great friction, are all seen to exist only in imagination. In the cylinder which Mr. Vallance has in operation at Brighton, there is a space of above an inch in width, purposely left all round between the cylinder and the end of the carriage which forms the piston, against which the air presses to drive the carriage along; yet does not the air which rushes through this crevice (though it is in the whole equal to an aperture of two square feet), prevent the operation of the principle: its sole effect being a loss of a proportion of the power employed to drive the air pumps; a loss which Mr. Vallance intentionally submits to, for the sake of proving that a very large portion of air may rush by the piston end of the carriage, without preventing the effect of the principle.—Vide pages 30 and 31.
“Seventhly, nor will the degree to which it may be necessary to exhaust, or, as it may in other words be termed, the degree of ‘vacuum’ required, to move even a very great weight, interpose any insuperable difficulty. In the cylinder at Brighton, a party, consisting of his Grace the Duke of Bedford, the Earl of Lauderdale, Lord Holland, Lord W. Russell, Lady W. Russell, and another lady and gentleman, were all at the same time experiencing the operation of the principle, on the day I was last at Brighton, with a degree of exhaustion not exceeding two drachms per square inch; a proportion of vacuum which would lower the barometer about one-hundredth of an inch. Practice therefore proves, as well as the arguments in pages 47 and 48, that a very trivial degree of exhaustion will be sufficient to move a considerable load; and as it will be perfectly practicable to exhaust to a degree, that should render a barometer exposed to the vacuum inside the cylinder, several, if not many inches lower than one would stand exposed to the atmosphere, I do not think the amount stated in page 37 more than it may be possible to move at one time. And with reference to weights of 50 or 100 tons, such as locomotive engines draw at once, there will certainly be no difficulty at all, let the velocity they are moved at be what it may.
“Eighthly, under the trivial degree of exhaustion which will thus, generally speaking, be necessary, your Royal Highness will perceive, that rendering the cylinder sufficiently air-tight for the purpose, will be far less difficult than it is at first supposed. Indeed, I see so many different ways of doing it, that I am satisfied it would not, in practice, prove more difficult, nor indeed so difficult, as causing some canals I have seen, to retain the water let into them.—Vide p. 45.
“Ninthly, nor will there be any difficulty in regulating the motion of, and stopping the vehicle. The shortest way of rendering this evident to your Royal Highness, will be to suppose the end of the carriage which, when in motion, stands across the cylinder, at a right angle with its course, to be capable of turning on a pivot; so that it may be moved one quarter of a circle, and placed in a line with the course of the cylinder: or edge to wind, like a sail when it shivers. The consequence of this would be, that as the air would pass by without pressing against it, the power which moved the carriage forward would be taken off; and as the wheel could at the same time be dragged by a friction lever, while other levers caused friction against the side of the cylinder, the progress of the carriage could be commanded and stopped at pleasure. This method of removing the effect of the pressure of the air against the carriage, not being that which would be made use of in practice, my reason for adverting to it, is solely to enable your Royal Highness to perceive, that a very simple arrangement will admit of its being done. For the same reason, I only state, that to the axis of each carriage, would be connected clock work, which would shew the person who has charge of the carriage how far he has gone, and where he is, to a yard; so that there will be no uncertainty as to when and where to prepare for stopping, by gradually diminishing the motion of the carriage. There will be every facility for perfect vision, as at each end of every carriage will be fixed a portable gas light.
“Tenthly, this principle possesses an advantage over common roads, as well as rail-roads and canals, which will, under all circumstances, be generally, and, in some cases, highly important. This advantage is, that the cause of motion (the atmospheric pressure) will act vertically as well as horizontally; and that in consequence of it, the filling up of hollows, and also deep cutting, as for canals and rail-roads, is unnecessary. Not that it would be advisable to select hilly ground; though perfectly possible to go over any, the most abrupt rises, even were they nearly perpendicular. But that any rise or fall over which a carriage road can be cut, would be quite level enough for the operation of the principle.
“Eleventhly, I now mention the expense per mile, which I think will not, in Russia, exceed 10,000_l._ The calculations on which this opinion is founded, I do not here submit to your Royal Highness; but at such time as may be necessary they will be ready for transmission.
“Twelfthly, the expense of transit, or carriage, by this principle. Assuming that the combined effect of the improved railway in the cylinder, and the six-fold diameter of the wheels, should not render any given power capable of moving more than on the single-line railway (vide my Report of August, 1825), one horse would move twenty tons; but independent of the effect which the wheels, being six times larger, would have in diminishing friction, the expense of transmission would be diminished many times, from the following circumstances:—On the single-line railway, the power employed is that of horses; and, considering the construction of that railway, and the height the rail must be in some situations above the ground, I do not conceive that locomotive engines can be ever used upon it. Horse-power is twenty-four times as dear as elementary power, employed in the way the Treatise points out. Assuming, therefore, that the friction of the rarified air against the inside of the cylinder, as stated at pages 68 and 74, should increase the power required ten times, still would the expense of carriage be less than by the single line railway, while we should attain the important advantage of being able to transmit 10,000 tons, at any rate between what railways now transmit at, and 100 miles per hour, for an expense which, as relates to power, would be only the twenty-fifth part of a farthing per ton per mile.
“But even were the friction of the rarefied air against the inside of the cylinder to increase the power required ten times, as I have supposed, it is not imperative that the expense of transmission must be increased in a similar degree. Owing to its being well-known and universally received, steam is the first mover, or power, Mr. Vallance has referred to. The researches of men of science in England have, however, been for some years directed to means of rendering the gases first movers, instead of steam, under the hope of obtaining an agent, which should serve as a mechanical first mover, without fuel. From the year 1820, the attention of Mr. Vallance has been directed to this subject, with a view of rendering the method of conveyance the Treatise refers to perfect, in the particular of cheapness of transmission; and about two years ago he obtained a patent for a first mover, which will give ten times the power of steam, without any expense for fuel; the principle of which is stated in the Tract, marked letter B, which I have obtained from him, for the perusal of your Royal Highness. The power therein referred to, proposed to be used instead of steam, would so greatly reduce the expense of transmission, that the cost of power would be ten times less than by the single line rail-road.
“It will also be equally superior in point of safety and security from accidents, as it is in point of economy and expedition: it being, as stated in page 81, absolutely impossible to be overturned.
“Thus combining expedition exceeding that of posting, with economy equal to that of canal transmission, it must appear that this principle is most importantly advantageous to an empire so vast in its extent as that of Russia, and, consequently, fully authorizes me most strongly to recommend that the Government should immediately contract with Mr. Vallance, to send a practical illustration of the principle, such as he has in operation at Brighton, which, being capable of carrying your Royal Highness, the Members of the Council, and Generals of the Arrondissements, over a space sufficient to demonstrate the practicability of the proposition, will place within command a reply to all objections from ignorant or interested persons.
“It has been deemed essentially important to the welfare of Russia to promote internal communication by canals, and immense sums have been expended in cutting them; but owing to the long duration of winter, they are useless during half the year; and so slow is the rate of transmission by them, that, even when in full operation, they can hardly serve to convey goods from one part of the empire to the other, before winter locks them up again. Railways also, owing to the period the snow lays on the ground, and the continual drifting of it which takes place, would be available scarcely more than half the year. But the principle here adverted to, being liable to interruption from neither frost nor snow, and equally effective by night as by day, offers a means of rendering the extremities of the empire contiguous to each other; and will do this at a much less charge than can ever be done by canals, or any other mode of conveyance.
“The vast importance of this principle to Russia, both in a military and commercial point of view, it is unnecessary for me to state to your Royal Highness; but I consider the manifold advantages it presents sufficiently demonstrated, to prompt me to recommend its speedy adoption from St. Petersburgh to Tsarsko-selo, the river Volga, Moscow, and the Black Sea.
“WILLIAM COULING, K. V. &c.
“London, Dec. 21, 1826.”
With these evidences that I do not presume to request your attention relative to a mere theory, I trust I may be permitted to hope, that the following observations relative to effecting a communication between your canal at Kensington and the point of termination you propose, may be deemed not wholly undeserving attention.
Were you to purchase land for either a canal or a railway, the width required would not be less than sixty or seventy feet, while in some parts it would be much more on account of the cuttings and embankments. {26}
Supposing the method which I submit to you were to be adopted, a width of only eight feet would be necessary, even were the tunnel to be carried, as a canal or railway must be, along the surface of the ground; so that my proposition has, to recommend it, this first feature, that only one-eighth of the ground would be wanted that must be required for either a canal or railway; while this recommendation would be attended with the additional advantage, that, instead of the tunnel rendering the lands through which it would pass, open, and liable to the depredations of the bargemen and drivers, as canals or railways do, it would, owing to communication going on _inside_ the tunnel, leave them still as private, untrenched upon, and uninvaded, as a water or gas pipe would do.
In order, however, still more to obviate objections as to the course, and additionally to reduce expense as to the nature of the ground required for the line of communication which I suggest, I propose carrying the tunnel _under_ ground, in lieu of upon it; while, instead of taking its course across fields and cultivated grounds—as a canal or railway must do—I propose taking it along the line of (though buried underneath) certain bye-roads and (to coin a word) uncultivatible grounds lying between your basin and the Grand Junction Canal, and the line of the London and Birmingham Railway; by doing which, I anticipate that very great expense, and still more important opposition, will be avoided; while, as the farm-roads and tracks, along and underneath which I propose to carry the tunnel, would be so importantly improved by it, as to be rendered almost equal to turnpike roads, the execution of the work would be an actual benefit, instead of an injury to the land under which it was carried.
In addition to these things, the line I propose would save five per cent. on the whole cost; owing to its being in that proportion shorter than the line pointed out on the plan for the railway which was laid before the meeting.
The course I propose is as follows. 1st. Along the road on the east of your basin, to the turnpike road; in which length I should sink it so as to go under the turnpike. 2nd. Diagonally across the turnpike to the bottom of Addison Road; up and underneath which it would be continued to the Uxbridge Road. 3rd. Under that road, and the farm yard and ground opposite Addison Road, to the Green lane which runs upwards by the side of Morland Hall; where would be the only _cultivated_ ground (and that only two or three furlongs) which it might be necessary to purchase.
From this point it would go under the track to Notting Barn Farm; and from thence under that farm yard up the track to the bridge now crossing the Grand Junction Canal; where I propose obviating any opposition of the Grand Junction company, by fixing the bridge which must be thrown across to carry the tunnel, _close_ to that bridge; so that there would still be, as it were, but one bridge for their barges to pass under.
From this point it might be carried under the short piece of road leading to the Harrow Road; and thence, under and across that road, up (though under) Kilburn Lane, to the line of the London and Birmingham Railway.
There being only between three and four furlongs, which are cultivatible throughout this route; and as the tunnel (being carried under them) would be no impediment to the usual operations of agriculture (unless some repair should, by chance, be necessary, while the crops were on the ground) the expense of the ground line, would, comparatively, be not worth speaking of; instead of proving the costly matter it would be, as relates to a canal or railway.
And the foundation which the width of the “lengths” of the tunnel would give for the railway inside it, being thirty times greater than those of the bases on which the rails of the Liverpool and Manchester Railway are laid (_those_ bases too, being of an extra and unusual size) the tunnel would be less likely to need repair as relates to its foundation, than the Liverpool and Manchester Railway is, by thirty times. Indeed, owing to the less weight there will be on each “length” of the tunnel, in comparison with that thrown on the railway bases, the probability of repair proving necessary will be less than this.
The stone blocks, or bases, which carry the rails of the Liverpool and Manchester Railway are two feet square. The weight of the large locomotive engines on that railway, is above ten tons; more than half of which, being thrown on two of the wheels, each block has three tons weight on it when those wheels pass over it. The pressure on every square inch of the foundations of the Liverpool and Manchester Railway, is, consequently, above four times as much as on the boilers of Boulton and Watt’s steam-engines; from which result the sinkings, “drivings into the ground,” and the twenty-fold more expensive repairs than were originally calculated on, alluded to in the extract from the Foreign Quarterly Review, given at page 11.
Now as the construction of the carriages which would go in the tunnel, would prevent more than three tons being thrown on a “length” of the tunnel; and as each of these “lengths” would expose a base of 120 square feet to the ground, the pressure on each square inch of the foundation of the tunnel, would not be one-thirtieth of what it is on the bases of the Manchester and Liverpool Railway; which, taken in conjunction with the superior bases exposed by the tunnel, would, perhaps, render the probability of sinking less than one hundredth. It may, therefore, be presumed that after the tunnel was once fairly set in its place, it never would be necessary to disturb the ground over it.
Neither will the height to be surmounted by your extension, prove an at all serious impediment to the effect of the principle which the tunnel will enable us to put in operation.
As the pressure of the atmosphere, acting in all directions, admits of a tunnel being effective even were it fixed vertically, all gradations of ascent, fall, necessarily, within in its range; with varieties of effect, increasing in proportion as their angles approach the horizon. In consequence of this, the height to be surmounted in the course of your extension, is merely an impediment of degree; while the following circumstance will render that degree comparatively unimportant.
Few things are better known than that a Stage Coachman, when he approaches a rise of the road, pushes his horses to a gallop; because “the swing of the coach” (as he expresses it) “carries his cattle up the hill.” The principle is known to every one; while it is almost equally well known that the law of its operation, is according to the square of the velocity; so that the momentum of a coach which meets the hill with the horses pushed into a gallop that causes the rate of the vehicle to be 16 miles an hour, will (friction abstracted) rise four times as high as one that meets the hill when going at the rate of 8 miles an hour: the continuance of the operation of the power which overcame friction on the level, being (so far as relates to its counteractive effect) equivalent to an annihilation of friction.
This law is well known. Now let us see how this knowledge has been taken advantage of, by those who have had the expenditure of hundreds of thousands, placed at their discretion.
Rates of from 35 to 40 miles an hour, have been attained on the Liverpool and Manchester Railway for these four years. Supposing friction to be counteracted and neutralized, the momentum of a vehicle that was moving on a level at the rate of 36 miles an hour, would “swing” and cause it to rise up an inclined plane to the height of 43⅓ feet perpendicular, let the angle of ascent, or rate of rise, be what it might; while, as a velocity of 20 miles an hour, would, under similar circumstances, “swing” a carriage up 13⅓ feet perpendicular, and a velocity of 10 miles an hour, 3⅓ feet perpendicular, it needs not, _nor ever has needed_ any thing more than a proper arrangement of levels and inclined planes, to avoid _all_ deep cutting, high embanking, or tunnelling, in the line of a railway, except where a precipitous rise or hollow interposed itself.
It is true that it may, with reference to the deep cuttings and high embankments of the Liverpool and Manchester Railway be replied, that at the time these works were executed, it was not known that such great velocities could be attained on railways. {29a} But though it was not then _known_ that these rates of motion could be attained, yet was it as well known as it is now, that rates of ten miles an hour could be attained by horses: while, though the first line of the railway was laid out in 1824, and the present line in 1825, it was not till October, 1828, that it became decided whether horse or elementary power should be employed: vide pages 62, 67, 68, and 69 of Mr. Treasurer Booth’s “Account of the Liverpool and Manchester Railway.”