REPORT TO THE RUSSIAN GOVERNMENT.

“To His Royal Highness Prince Alexander, Duke of Wirtemburg, Chief of

the Corps of Engineers for the Inland Communications of Russia,

General of Cavalry, &c. &c.

“Your Royal Highness having commanded me to report upon all the

inventions of importance that have been brought forward in England of

late years, whether such were, or were not named in the instructions

I had the honour to receive from your Royal Highness in St.

Petersburgh in June 1824,1 beg leave most humbly to submit the

following particulars, relative to a proposed mode of conveyance;

differing from every existing system, as much as it will surpass them

in point of expedition and ultimate economy.

“In March, 1825, I was informed that a Mr. Vallance had invented a

method of conveyance, by which goods might be forwarded from place to

place ten times faster than can now be done; or equal to 100 miles

per hour. The apparent absurdity of the proposition, and the

undefined explanation then given, induced me to consider the scheme

as one of the nefarious and stock-jobbing bubbles of the day;

consequently I took no measures to become correctly informed on the

subject; particularly as I was about leaving London for an extensive

journey in the interior. Recent circumstances have, however, caused

me to entertain so different an opinion to that which I then held on

the subject, that I can now confidently submit to your Royal Highness

an account of a method of conveyance, which will, in my humble

opinion, within a few years, operate a change in the condition of the

whole civilized world; and which would be productive of the most

important benefits to the Russian Empire.

“The theory of this method is stated in the Treatise marked with the

letter A. The practice, I have experienced personally: having been

conveyed over a space sufficient to demonstrate the practicability of

the principle; and although that space was not sufficient to admit of

any such velocity being attained as is adverted to in the Treatise,

yet there is sufficient evidence of the velocity with which air may

be made to move, to satisfy any one, that on a line of proper length,

the only limit to the rate at which persons or goods may be conveyed,

will be that at which wheels will revolve. I will, however, first

advert to the general object of the Treatise, and then comment on

those parts of it which I conceive to require further illustration.

“Your Royal Highness will perceive, upon a perusal of the treatise,

that the general object of the author is to prove,

“1. That it is practicable to render air a means by which we may

cause a peculiar sort of wheel carriage to convey both passengers and

goods ten times faster than horses can draw any vehicle now in use.

“2. That this may be done with perfect safety and convenience.

“3. That we may, at one and the same time, move a weight exceeding

that of 100,000 infantry or 10,000 cavalry; and, consequently, that a

whole army may, in an hour, be transported over a space of 100 miles.

“4. That this method of transmission may be put in practice, for an

expense per mile, far less than what several canals have cost, as

will be apparent from the amounts of the several inland navigations

of the United Kingdom, stated in my Report of January last.

“5. That the expense of transport by it will be so many times less

than by any present method, that military as well as commercial

benefits will result from it of the most important nature; and

“6. That the stoppages, inconveniences, and delays, which would

otherwise arise from those who have charge of the exhausting

apparatus at each end of the line of transit, setting it in operation

at an improper time, may be prevented by the new mode of telegraphic

communication described in the last section of the Treatise, which,

being equally efficient during the most foggy weather and darkness,

as in day light and clear weather, will admit of instantaneous

communication between those who direct the operations at each end; so

that any thing which it may be necessary should be known at one end,

may be instantaneously communicated from the other, independent of

the method of conveyance itself; an arrangement, without which, the

operation of the principle would ever be attended with doubt, delay,

and danger.

“The vast importance which a method of transmission, combining the

advantages of tenfold expedition and cheapness, must be, to an empire

so extensive as that of Russia, I will not presume to point out to

your Royal Highness, but pass to those particulars which appear to me

to require further elucidation than the author’s object allowed of

his giving.

“The first thing is, the velocity at which the cause of motion, in

this method of transmission, viz. the air, would move us, provided we

could construct wheel carriages to go so fast. This velocity would,

if raised to its maximum, be between 900 and 1000 miles an hour. But

as saving nine-tenths the time now wasted in travelling post, would

render the saving of portions of the remaining tenth, very

unimportant, it will be unnecessary to trouble your Royal Highness

with proof that it might be possible to do so, in perhaps a large

proportion; and I therefore pass to the adduction of evidence, which

shows that _it is certainly in our power to save nine-tenths_.

“From the examination I have given to the construction, and what I

have experienced as to the effect of the cylinder, or large tube, in

which I was conveyed, according to this principle of transmission, I

am convinced that exhaustion, to a degree which should give fifteen

inches of mercury, may be effected—that is, half a vacuum; and as

this would give an initial velocity of between 200 and 300 miles an

hour, there is no reason to doubt but that a rate of motion equal to

100 miles an hour may be attained, provided wheels can revolve so

fast without igniting. The operations of nature frequently impart to

air a velocity of above 100 miles an hour; and in the process of

fusing iron, it is artificially caused to move at rates varying from

200 to nearly 700 miles an hour. At the lower rate of 100 miles an

hour, it must therefore be fully practicable to make it move.

“The second thing I advert to, is, the quantity in which air may be

exhausted, or taken out of a cylinder, or line of large pipe, such as

is adverted to. The blast cylinders used instead of bellows, for

fusing iron, are all air pumps, and it is requisite only to arrange

the valves properly, to render them condensing or exhausting pumps at

pleasure. Many of these pumps are large enough to exhaust 10,000

cubic feet of air per minute. Assuming the area of the cylinder to

be 100 square feet, {22a} and the velocity at which we are to be

conveyed to be 100 miles an hour, the combined operation of

eighty-eight of these pumps would be required. But the one referred

to in page 18, will take out 22,000 cubic feet per minute; therefore,

only forty such pumps as that would be required to exhaust air from

the cylinder at the rate of 100 miles an hour—a number, the operation

of which there will be no difficulty in combining.

“The pressure requisite to cause air to move at the rate of 100 miles

an hour, appears, by all experiments that have been made on the

subject, to be less than half a pound per square inch. Calculating

from this datum the power requisite to move a column of air equal to

the area of the cylinder, at the rate of 100 miles an hour, would be

that of 1900 horses. {22b}

“A steam engine of fifty horses’ power would, therefore, be required

to each air pump, to cause the air to move at the rate of 100 miles

an hour, independent both of the load to be moved, and of the

friction of the air against the inside of the cylinder. With

reference to the first of these—the load to be moved—it is to be

observed, that, owing to the principle combining the operation of by

far the best railway I have ever seen, or, indeed, can conceive, with

carriage wheels six times as high as those used on the patent single

line railway, friction is diminished to a degree which will admit of

the same power moving a considerably greater weight than on that

railway. It will, therefore, be quite safe to calculate only on the

same effect being produced; and, according to this the extra power

requisite to move 100 tons at the rate of 100 miles an hour, would be

only 200 horses. With reference to the friction of the air against

the inside of the cylinder, as referred to at pages 68 to 74, several

times the power will be required; so that, were there no other means

of power and exhaustion than steam engines and air pumps, objection

might arise in point of expense. But, by what is stated at pages 50

and 51, it appears that neither air pumps nor steam engines would be

indispensably necessary; and although Mr. Vallance does not at

present deem it prudent to give full explanation on this particular,

he informs me, that whenever it may be requisite, he is prepared to

prove that every purpose of exhaustion may be effected without other

apparatus than what he can construct out of rough hewn trunks of

trees; so that the question may be considered free from any

objections which the necessity for costly machinery would give rise

to in Russia.

“Thirdly, that a vehicle capable of carrying both passengers and

goods, can be so adapted to the inside of the cylinder as to be moved

in it by the air when operated upon by the air pump, I can vouch,

from having seen and experienced it; and as the rate at which this

vehicle moves, is exactly commensurate with that at which the pumps

exhaust air from the cylinder, it follows, that, at whatever rate air

can be pumped out of the cylinder, the vehicle will be carried

forward, provided that velocity does not exceed the rate at which

wheels can revolve on their axes without ignition: with reference to

which, it is to be observed,

“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.”

And notwithstanding that instances of velocities equal to ten miles an

hour having been attained by locomotive engines, were not very common at

the time the line of the Liverpool and Manchester Railway was laid out,

yet do the under-quoted extracts from various publications of the period

prove, both that they _had_ been attained, and that much higher

velocities were confidently anticipated: while Mr. Treasurer Booth, at

page 37 of his book, says, that “the earth work (comprising the cuttings

and embankings along the whole line) was not commenced till January,

1827.” {29b}

Such statements being (as it were, officially) promulgated, and such

opinions entertained relative to the velocities attainable by locomotive

engines:—the question as to the employment of horses being, thus, an open

one, not only during the survey for the second line, but also for two

years and a half after the Act for the Liverpool and Manchester Railway

was obtained; and it being equally well known as it is that the sun gives

light, that for the gallop which coachmen push their horses to just

before touching a hill, in order to give their vehicles the momentum

which imparts the “swing that carries their horses up the hill”, rates of

15 or 16 miles an hour could be attained—it being thus known at the time

the line of the Liverpool and Manchester Railway was laid out, that

average velocities of 10, and occasional velocities of 15 miles an hour

could be attained: and it being unquestionable that if friction be

counteracted (as it is by the continuance of the operation of the moving

power) the momenta imparted by those velocities will carry any vehicle up

any inclined plane to the heights of 3⅓ and 7½ feet, it was necessary

only to have laid out the railway in short levels, with sharp inclined

planes rising a foot or two between them, to have avoided all deep

cutting or high embanking.

It is true that owing to velocities of ten miles an hour, having at that

time, been only occasionally attained by locomotive engines, it might

have been proper to keep these ranges of levels, and inclined planes

_within_ the limit prescribed by that rate. But as this limit is not

within a vertical rise of 3 feet 4 inches, it would have been perfectly

possible, by arranging short levels with sharp inclined planes of three

feet in height between them, to have avoided the _whole_ of those deep

cuttings and high embankments of the Liverpool and Manchester Railway, of

which the under-quoted extract from Mr. Treasurer Booth’s book gives such

glowing descriptions. {30}

Admitting, however, (for the question’s sake) that the “most eminent

engineers” and their “assistants of undoubted talents,” by whom these

“Pelion-upon-Ossa-like spoil banks, towering over the adjacent land” were

ordered—and of which Mr. Booth says, in addition, “this aggregate mass

has been removed to various distances, from a few furlongs to between

three and four miles; and no inconsiderable portion of it has been

hoisted up by machinery from a depth of 30 to 60 feet”—admitting that

these gentlemen should have been warranted in expending the hundreds of

thousands which were paid for making these mountains between Liverpool

and Manchester, by the uncertainty then prevalent as to what velocities

were attainable by locomotive engines, it cannot be said that the

engineers of the London and Birmingham Railway have any similar

justification to plead. That line was not, I believe, laid out till

1831, while the velocities attained on the Liverpool and Manchester

Railway, and the short time within which London and Birmingham could, in

consequence, be brought of each other, form the main features of the

prospectus: rates of from 35 to 40 miles an hour having been (then)

_long_ attained on the Liverpool and Manchester railway.

Yet does the “Estimate” laid before Parliament shew no less a sum than

429,286_l._ appropriated to “Excavations, Embankments, and Tunnelling,”

which, with “the increase in the number of arches in the Wolverton

viaduct,” will give an _estimated_ expenditure of nearly half a million

to do that, which, taking _proper_ advantage of the law of motion I am

adverting to, would entirely have saved; except where a hill as

perpendicular as a wall, or a hollow as precipitous as a well, rendered

tunnelling, deep cutting, or filling up, absolutely unavoidable.

At the time the Birmingham Railway was before Parliament last session,

maps of it were issued from the office of that company, which gave the

“Section of the line of railway; shewing the rises and falls.”

This section is on too small a scale to shew either the height of the

embankments or the depth of the cuttings: and though it has not suited my

convenience to spare the time necessary for examining the section

deposited in Parliament, yet as the cubic yards of cuttings and

embankments amount to nearly twenty-three millions: as the map and

section I have just mentioned shew ten tunnels (some of which are a mile

and upwards in length): and inclined planes, in _unbroken_ rises of 6, 8,

10, 11, 13, 20, and 25 miles, there can be no doubt but that _much_ deep

cutting and high embanking is included in it. Now though I do not mean

to imply that the expense of _all_ cutting and embanking could have been

saved, by taking proper advantage of the power of ascending heights,

which is imparted by the momenta of the velocities whereat locomotive

engines now go, yet I do mean to state it as my full conviction, that had

this railway been (as the second prospectus of the Liverpool and

Manchester Railway, stated that line should be) “laid down and arranged

with that skill and conformity with the rules of mechanical science,

which will equally challenge approbation, whether considered as a

national undertaking of great public utility, or as a magnificent

specimen of art” the whole of the anticipated expenses of _deep_ cutting

and _high_ embanking would have been expunged from the estimates; it

being certain, that deep cuttings, high embankments, and _long_ inclined

planes are no more evidences of engineering skill, than winning a battle

by hard fighting is of generalship: while the expense of the numerous

“very small cuttings varying from 8 to 10 feet,” which are spoken of in

the “Minutes of Evidence taken before the Lords’ Committees,” might as

certainly have been saved, and those rises passed over by the vehicles in

consequence of their momentum; as a cricket ball will roll over a

mole-hill.

But if these remarks are applicable to the Birmingham Railway—the line of

which, was I believe, laid out in 1831—what must be said relative to the

_now_ proposed London and Bristol Railway?

For nearly twelve months the principle of avoiding level, and

constructing “undulating railways” has been discussed, in consequence of

Mr. Badnall having taken out a patent for, and published a work,

proposing such “undulating railways”: and though, owing to the fall on

your line being wholly (as well as _greatly_) one way, it is not

necessary to express any opinion here on a proposition, which appears to

have for its object the construction of unlevel railways _in preference_

to level ones, and the labour of toiling up hill for the sake of the

momentum to be obtained by running down hill, yet as, in consequence of

it, the effect of momentum in carrying moving bodies up ascents, has been

largely and widely adverted to for the last twelve months (nearly), it

must have been within the expectation of every one, that, let the

gentleman who has been employed to lay out the line of the Bristol

Railway be anxious as he might, to avoid any “undulating” proposition, he

would be equally anxious to call in the aid of all _known_ and

_established_ principles, to diminish the expense of the line he was

required to lay down. {32}

Now, nothing, I believe, is more certain, than that if a vehicle be

moving along a level at the rate of 2¾ (2.7272) miles an hour, it will,

on coming to an inclined plane, and provided the operation of the power

which overcame friction on the level, be continued, so as to neutralise

and (as relates to counteractive effect) annihilate friction during the

ascent, “swing” itself up, and rise to the height of (that is, its

momentum will cause it to rise to the height of) three inches

perpendicular; let the angle of ascent, or rate of rise of the plane, be

what it may.

Equally certain is it, that if the velocity of the vehicle be twice 2¾

miles an hour, that is 5.4544 miles, the momentum will (under similar

circumstances as to counteraction of friction) then cause the vehicle to

rise up said inclined plane to four times the height to which the former

velocity raised it; or to the height of one foot. And it is equally

certain, that the momenta imparted by increased velocities will, under

the circumstance of the friction of the vehicle being overcome,

neutralised, and (as relates to counteractive effect) annihilated, by the

continued operation of the moving power during the ascent, cause the

vehicle to rise up any inclined plane to the perpendicular heights stated

in the following table:—

Carriages moving on levels, at the Have momenta, which (friction

under-mentioned velocities, the being counteracted and

motions of which are changed from neutralised) will cause them

horizontal to ascending, by means, to rise to the

either of circular or angular under-mentioned heights

ascents. (perpendicular) above the

level where those velocities

were attained: let the rate

of rise, or angle of ascent,

be what it may.

MILES. MILES PER HOUR. PERPENDICULAR.

2¾ or 2.7272 3 inches.

5½ or 5.4544 1.0 foot.

11 or 10.9088 4.0 feet.

22 or 21.8176 16.0 do.

44 or 43.6352 64.0 do.

88 or 87.2704 256.0 do.

176 or 174.5404 1024.0 do.

352 {33} or 349.0808 4096.0 do.

Now, let it have been proper as it may, that the gentleman whose name

appears as “Engineer” to the Bristol Railway, should (in laying out that

line) have avoided encumbering the subject with the “undulating”

question, there can be no doubt that it was incumbent on him to diminish

expense in every way which _established_ principles admitted. And as the

usual railway rate is now 20 miles an hour, while that rate will give

momentum enough to cause any vehicle to rise up any inclined plane to the

height of 13⅓ feet (perpendicular) above the level on which it was

running at the rate of 20 miles an hour, it is necessary only to lay out

the line of this railway in levels, and rises of 10 feet each, to avoid

(very nearly, if not _quite_) all necessity for cutting, or embanking;

while _deep_ cutting, _high_ embanking, and tunnelling, might (except in

_very_ peculiar cases) have been as certainly avoided, as erecting a

suspension bridge will obviate the necessity for piers and arches over a

river. Yet does not this gentleman appear to have any more called in the

aid of this law of motion, than did those equally “_eminent_ engineers”

who laid out the line of the Liverpool and Manchester Railway; or those

who have laid out that of the Birmingham Railway: the “Report” of the

public meeting held at Bristol, on the 30th July last, stating that

“although the line of country (except for about 30 miles at the Bristol

end) is _very advantageous_, yet the comparative levelness of the railway

will be attained by a _great deal_ of deep cutting, and _several_

tunnels;” while the prospectus issued from the London office of the

Company states, that “the construction of a road so nearly level, in the

hilly country about Bath and Bristol, will, unavoidably, be a costly

work.”

The length of the Birmingham Railway is 112½ miles; that of the Bristol

Railway “from 115 to 118 or 120 miles,” average 117½. The estimated

expense of the cuttings, embankments, and tunnels, of the Birmingham

Railway is 429,286_l._ or 3,185_l._ per mile. The same expense on the

Bristol Railway is (835,300_l._ + 15,000_l._=) 850,300_l._ or 7,236_l._

per mile; that is, above twice as much: and this too, notwithstanding

that the Report states that “this expensive part of the work,

fortunately, lies principally in two of the most favourable materials—the

chalk and the freestone;” and also notwithstanding that the estimate of

the Birmingham Railway has undergone two years’ scrutiny, and the most

rigid investigation, by several Parliamentary Committees; while that for

the Bristol Railway is the result of only a “_preliminary_ survey,”

directed by a “Provisional Committee:” so that were it to be increased as

the estimate for the Birmingham Railway has been increased, it would be

_many_ times as much as the similar work on that railway. Indeed, the

parties themselves have made a considerable increase already: 10 per

cent. being added to the above amount of 850,300 by the Bristol

Committee, and 7 per cent. by the London Committee; {34a} so that

978,494_l._ is the _whole_ amount at present allowed for works, which

taking proper advantage of the momentum of the vehicles would have saved.

Yet, with well-known laws of motion thus set at nought and neglected, and

with expense thus unnecessarily as well as most enormously added to, are

the Committee—gentlemen who were, unavoidably, as entirely dependant on

the opinion of their engineers, as the Ministry of 1789 were upon that of

the “Insanity Doctors,” relative to the mental affliction of George III.;

or as those of 1830 were on that of the physicians who attended George

IV. during his long illness—under circumstances of such entire dependence

on the opinion of their engineers, are the “Provisional Committee” of the

Bristol Railway led into the following expressions of approbation in

their Report: “The Committee think it but justice to say, that the zeal,

the diligence, the _ability and other valuable qualities_ manifested by

these gentlemen, have given them ample reason to congratulate themselves

on their choice”!; and “The Committee, in conclusion, _repeat_ that they

have carefully availed themselves of the resources of _skill and

experience_ in investigating the probable cost of the railway.” {34b}

Now as, were I to presume to manifest “skill, experience, ability, and

other valuable qualities,” _such as these_, with respect to your line, or

thus to throw away, not only hundreds of thousands, but also half

millions, on any other, I should be sure to experience the truth of that

proverb, which says that merely looking over the hedge shall subject one

man to the operations of “the _finisher_ of the law,” while another man

may steal the horse with impunity, I must avail myself of this law of

motion, which “skill, ability, experience, and other valuable qualities”

so neglect and despise, to get loads up the rise which you wish to

surmount, without resorting to deep cutting or high embanking.

Sixty feet of the rise to be surmounted, occurring in the last half-mile

of your line, I shall have nearly two miles to acquire the necessary

velocity in: and as the continuation of the action of the power which

overcame friction on the level, will neutralise, and, as relates to

counteractive effect, annihilate the friction of the carriages while

ascending these sixty feet, I have only to cause them to attain a

velocity somewhat greater than has yet been attained on railways, that

is, 42½ miles an hour during the two miles, to enable them to “swing”

themselves up these sixty feet, in consequence of the momentum which that

velocity will impart: while, let the height of Rodway Hill (which is

adverted to as so desirable to avoid, in the Report of the Provisional

Committee of the Bristol Railway) be what it may, all that would be

requisite to obviate the necessity for the “inclined plane and stationary

engine” spoken of as unavoidable there, would be to attain the velocity

due to the altitude of said hill, to enable my vehicles to surmount it

from their momentum.

Nor would the ascending power imparted by the vertical operation of the

pressure of the atmosphere, be much less important with respect to

diminishing the expense of bridging, on the line of this Bristol Railway,

than would “momentum” as relates to the expense of cutting and embanking.

From the map issued from the London office of that Company, it appears

that that railway is to be carried five times across the Avon; twice

across the Kennet and Avon Canal; three times across the Wilts and Berks

Canal; and four times across the Thames. These various crossings are not

for the sake of approaching places of magnitude, or commercial

importance; but solely because the _principle_ of railway transmission

compels the level to be servilely adhered to: while, though the right

line distance between London and Bristol is only 108 miles, yet is the

line of railway there laid down, shewn as being 120 miles long; the 12

additional miles being added by the curves taken in thus crossing these

waters for the sake of the level.

Now though I do not mean to say that it would be possible, by laying down

a tunnel instead of this railway, to avoid all bridging whatsoever, yet

owing to hills and rises being no impediment to the operation of this

principle, the line for a tunnel might be several miles shorter than this

line of the railway, and yet the whole of these bridges be saved,

excepting one over the Avon; while not a quarter of the expense would be

incurred for carrying a tunnel over the waters which _its_ course must

cross, which will be incurred in bridging the railway over those other

waters that intersect its course, which are not laid down in the map

shewing its line.

The estimated expense of bridging for the railway is 474,800_l._; which,

when increased by the per centages allowed by the Committees, amounts to

556,194_l._ as the whole _estimated_ expense of bridging. What

proportion of this amount is for bridging over waters, and what for

bridging over roads, is not stated. On the Liverpool and Manchester

Railway 108,565_l._ 11_s._ 9_d._ was expended on 63 bridges; of which

only five were over waters: the other 58 being over roads, or to carry

roads over the railway. On the Birmingham Railway the number of bridges

is 300; of which only nine _are stated_ to be over waters, the others

being for roads. The estimated amount of them is 350,574_l._ One bridge

alone (the Sankey viaduct) on the Liverpool and Manchester line, cost

nearly 50,000_l._

Now as the power of going up or down, imparted by the vertical operation

of the pressure of the atmosphere, would render it wholly immaterial

whether the level was preserved in the line of a tunnel; as burying it

under ground, in the manner proposed at page 27, would equally do away

with any occasion for the _many_ hundreds of bridges, which, on the three

lines I have mentioned, must be provided to carry those railways clear of

roads, as it would save bridging over the roads on your line; and as a

tunnel could have been carried _under_ the Sankey, for almost one-tenth

of the expense it cost to construct the viaduct by which the Liverpool

and Manchester Railway is carried over that canal—as my principle offers

facilities of this kind for obviating the necessity of bridging—I do not

hesitate to say, that, on the whole three lines, and considering how much

the actual, will exceed the estimated amounts, above one million sterling

might be saved in the item of bridging alone, by substituting tunnels for

railways; which, when added to, as it would be, by the almost equal

amount that would be saved in the expense of the land, in consequence of

my plan requiring a width of only ten or a dozen feet _under_ ground,

instead of from 60 to 300 on the surface, will admit of my saying that

(in round numbers) nearly two millions might be saved by my plan, in

these two items of bridging and land, on the lines of the Liverpool and

Manchester, the London and Birmingham, and the London and Bristol

Railways: while, if what my plan would save of the 398,286_l._ allowed

for the cost of land, and of the 261,928_l._ allowed for that of the

entrances to London, Bath, and Bristol, be added to the savings I have

stated it would effect in bridging, cutting, embanking, and tunnelling, I

may say that it would also save nearly two millions (of the _present_

estimated expense) on the Bristol Railway alone.

The ten times greater heights than I have yet specified, which may be

surmounted by combining the operation of the momentum of the _air itself_

with that of the vehicles, it is not necessary for me to trouble you

with, owing to the shortness of your line, and the small height to be

ascended: though it may be permitted me to observe, that as attaining

only equal velocities to those which have been spoken of as attainable by

locomotive engines and steam-coaches, will enable my vehicles, of

themselves, to surmount hills of many hundred feet in height; while

combining with their momentum, the momentum of the air itself (that which

is _before_ the vehicles; the friction whereof will be overcome, and

neutralised by the operation of the exhausting apparatus) in tunnels of

proper length, and loads of corresponding weight, will enable me to

ascend more thousands of feet, than the momentum of the vehicles alone

will carry them up hundreds, I may be able to extend Louis le Grand’s

exclamation, “Il n’y a plus des Pyrennées,” to “il n’y a plus des

montagnes sur la terre,” so far as relates to their longer preventing

intercourse between countries; and consequently render the whole earth

level to us, in point of effect.

In reference to the force required to overcome the friction of the medium

by which the moving power operated to impel the carriages, would a tunnel

be also superior to a railway. From Messrs. R. Stephenson and Locke’s

reply to Mr. Walker’s Report to the Directors of the Liverpool and

Manchester Railway, it appears that the friction of the ropes by which

stationary engines draw waggons up inclined planes, is one-twelfth of

their weight: while, as the latter part of your line gives a sharper rise

than that of the Liverpool tunnel, the weight of the rope you must use

should not be less than 7lbs. per yard; the friction and gravitation of

which would be 0.73231b. per yard, or 1289lbs. per mile. The line in the

plan for the railway, which was laid before your meeting, being 2½ miles

long, the whole resistance of friction and gravitation upon it would be

3222 lbs.

From experiments on the friction of air in tubes, I am enabled to state

that both the inertia and friction of the air against the inside of an

equal length of the tunnel I propose to you to lay down would not, when

said air was moved _by exhaustion_, and conveying 50 tons at the same

rate at which the same quantity is drawn up the tunnel of the Liverpool

and Manchester Railway (i.e. ten miles an hour), be so much as one

sixteenth part of this; while it would have this important advantage,

that the heavier the load was, the less would be both the inertia and

friction of the air. For instance: the degree of exhaustion requisite to

admit of an equal load to what is drawn up the Liverpool tunnel (i.e. 50

tons) being moved up a tunnel of the same size as that I constructed at

Brighton, and rising at the same rate your’s must rise (1 in 47) by the

pressure of the atmosphere, would be about the 40th part of a vacuum.

But supposing ten times this load were to be raised, the degree of

exhaustion must be ten times as great, or about the fourth of a vacuum.

And, as the greater the exhaustion, the less the expansive power, and,

consequently the less the inertia and friction of the air inside the

exhausted part of the tunnel, this “rope of air” as it has, derisively,

been called, possesses the important advantage of decreasing as relates

to the density, inertia, and friction, which _itself_ opposes, in

proportion to the increase of the load drawn by it: while, as the valves

I should place at every quarter, or half, or whole mile, to be opened by

the carriages as they pass them, and admit air immediately behind said

carriages, would prevent there being the inertia and friction of more

than a few hundred yards of air of the _natural_ density behind the

carriages to be overcome, the impediment which presents an insuperable

obstacle in the opinion of the numbers who have condemned the proposition

(because they deemed operating by exhaustion the same as operating per

plenum) diminishes, in point of fact, to a far less important hindrance,

than that which is occasioned by the old system of drawing loads by means

of stationary engines and ropes; since, in the present instance, the

inertia and friction would not be the one-hundred-and-sixtieth part of

what it would be, to move an equal quantity by the stationary engine, and

rope system.

And notwithstanding that the superiority which the tunnel possesses over

the locomotive system is not so great at this, yet is it important.

In the instructions given to Mr. Walker by the Directors of the Liverpool

and Manchester Railway (and which called from him the Report criticised

by Messrs. R. Stephenson and Locke), it is stated that “the quantity of

traffic for which it will be expedient to provide the power of

conveyance” is about 4000 tons, from each to the other of those places,

daily.

In his publication on the Liverpool and Manchester Railway, Dr. Lardner

says, “In the experiments which I have detailed, it appears that a steam

engine is capable of drawing 90 tons at the rate of about 20 miles an

hour; and that it could transport that weight twice between Liverpool and

Manchester in about three hours.” {38a} The weight of this engine alone

being 8.1 tons, the whole weight of itself, and its tender, with the

necessary supplies of fuel and water, will not be less than twelve tons.

Therefore, the friction of the engines (and their tenders) requisite to

carry these 4000 tons at the rate of 20 miles an hour, would be 4267 lbs.

The friction of one mile of air in a tunnel eight feet in diameter, when

moved at the rate of 20 miles an hour by _exhaustion_ being 288lbs., the

friction of it in a tunnel extending from Liverpool to Manchester, will

be 8640lbs.: which, though double the friction of these locomotive

engines, might be far cheaper for the following reason; and independent

of the circumstance, that I could lay down a tunnel capable of carrying

all these 4000 tons at one and the same time, from Liverpool to

Manchester, for one-fourth of what that railway has cost; {38b} and also

independent of the circumstance that the enormous expense now incurred

for the repairs of the locomotives (as stated on page 11) would also be

saved.

It is well known that the smaller a steam-engine is, the larger is the

proportionate quantity of fuel it requires, and the greater the

proportionate expense of working it; while it is equally well known that,

owing to the imperative importance of lightness and efficiency over

economy in locomotive engines, this disadvantage increases in a most

rapid ratio with respect to them. In consequence of this, a quantity of

fuel, which, in large stationary engines, such as I should use for

exhausting air from the tunnel, would do a given quantity of work, would,

in the best of the locomotives on the Liverpool and Manchester Railway,

do only one-sixteenth as much work.

Therefore it results, that, notwithstanding the friction of the air in a

tunnel 30 miles long would, at the rate of 20 miles an hour, be twice as

much as the friction of the locomotive engines, yet, owing to the fuel

consumed by the latter, to move themselves and their tenders, being

sixteen times as great as large stationary engines, such as I should use,

would require to do the same work, the tunnel would, supposing the whole

quantity of goods were to be carried at once, be eight times the cheapest

mean of conveyance, in point of current expenses only, and without

reference to its first cost being only one-fourth that of the railway;

and also without reference to the whole of the enormous expense now

occasioned by the repairs of the locomotive engines being saved.

But this is not the only proportion in which a tunnel might be cheaper.

The 13th paragraph of the Russian Engineer Officer’s Report, states, that

he is “convinced that exhaustion to a degree which should give a pressure

of fifteen inches of mercury may be effected in the tunnel.” Now,

notwithstanding that much more than this may be done in an iron tunnel,

yet will I calculate on this only. Fifteen inches of mercury being 7.3

lbs. that pressure on the area of the tunnel, would move above twice the

4000 tons which the Directors of the Liverpool and Manchester Railway

estimated would be carried from one to the other of those places every

day; which, supposing that weight to be conveyed at one time, would

reduce the expense (per ton of goods carried) of overcoming the friction

of air moving in a tunnel from Liverpool to Manchester, at the rate of 20

miles an hour, to one-sixteenth of what the power required to overcome

the friction of the locomotive engines required to draw the same weight

would cost.

And though, owing to its being a received opinion that the power required

to overcome the friction of fluids increases according to the square of

the velocity, we are to suppose that at 40 miles an hour, the fuel

required to overcome the friction of the air would be one-fourth that of

the locomotive engines, while at 80 miles an hour it would be equal to

that of the engines, still would a quadruple velocity be attained, by the

expenditure of only an equal quantity of fuel.

The amount of the power required to overcome the friction of the

locomotive engines (and their tenders) necessary to carry 4000 tons

weight from Liverpool to Manchester daily, at the rate of 20 miles an

hour, is, when expressed in “horse’ power” equal to the power of 225

horses working for an hour and a half. In other words, these locomotives

must exert power to this amount, beyond what is required to draw the 4000

tons weight.

The power required to overcome the friction of air, which was moving (by

exhaustion) at the rate of 20 miles an hour, in a tunnel of eight feet

diameter, extending from Liverpool to Manchester, would be equal to that

of 456 horses: which, though double the preceding, would yet be eight

times cheaper, owing to large stationary engines, such as I should use,

requiring only one-sixteenth part of the fuel required by locomotives to

do equal work.

At 40 miles an hour (supposing locomotives could go so fast) the number

of horses’ power required to overcome the friction of the air in the

tunnel would (according to the received opinion of that friction

increasing to the square of the velocity) be 3650: which, though sixteen

times greater than that of the locomotive engines and their tenders, yet,

in consequence of this power being exerted only for three-quarters of an

hour, instead of an hour and a half, and of fuel doing sixteen times as

much work in large stationary engines as in locomotives, would be only

half so expensive as the locomotives and their tenders would prove.

At 80 miles an hour (which is twice as fast as locomotives can go) the

power required to overcome the friction of the air in the tunnel, would

(on the calculation that it increases according to the square of the

velocity) be equal to that of 29,196 horses; which is nearly 130 times as

much as the locomotive engines would require: though, owing to this power

operating only 22½ minutes, instead of an hour and a half, and to fuel in

large stationary engines doing sixteen times as much work as in

locomotives, the expense would be only twice as great as in the

locomotives, exclusive of the whole of the most enormous expense now

incurred, by the repairs of the locomotives being saved (which would,

alone, more than make up the difference) and also exclusive of the tunnel

costing only one quarter of what the railway has cost, and of the rate of

conveyance being four times as fast.

But it is not with respect to a tunnel only, that the resistance of the

air opposes an impediment: this resistance being found so serious an

obstacle to the progress of the locomotive engines and their loads, that

in all trials of, or experiments with them, the state and direction of

the wind is noted and allowed for. In the “Account of the Liverpool and

Manchester Railway,” published by the Treasurer of that Company (H.

Booth, Esq.), he says: “Moreover, at great velocities, the resistance of

the air must not be left out of the calculation. At ten miles per hour,

it has been found by experiment, that the resistance of the atmosphere is

about half a pound weight on a square foot of flat surface; at fifteen

miles, the resistance is 1lb. per square foot; and at twenty miles, about

2lbs. per square foot: the increased resistance being, nearly, as the

squares of the velocities.” {40}

The surface opposed to the air by a steam-coach, the engines of which its

proprietor told me were equal to ten horses power, I found to be 30

square feet. That, opposed by another, the engines of which were said to

be equal to twenty horses power, I found to be above 50 square feet:

while, when carrying four outsides on the front of the roof, this coach

exposed nearly 70 square feet to the action of the air. The surface

opposed to the air by the large locomotive engines now used on the

Liverpool and Manchester Railway, I understand (when chimney, axle-tree,

wheels, and every thing that cuts the air, is taken into account) to be

about 40 feet square. Supposing it to be so, at 20 miles an hour, the

air will oppose resistance equal to 80lbs. to the progress of the engine;

which resistance having to be overcome at the rate of 1760 feet per

minute, is equal to 4¼ horses power. At 40 miles an hour, this

resistance would be 320lbs.; which resistance having to be overcome at

the rate of 3526 feet per minute, would be equal to 34 horses power. At

80 miles an hour, the resistance of the air would be 1280lbs.; which

resistance, having to be overcome at the rate of 7,040 feet per minute,

would be equal to 270 horses power; while at 100, and 120 miles an hour,

the power required would be, respectively, that of 528 and 912 horses.

Now, as the force required at 80 miles an hour, is a _few_ times more

than the whole power of those engines, and as Dr. Hutton found that

giving the moving body the form of a cone, the height of which equalled

the diameter of its base, diminished the resistance of the air only half,

it may serve to shew that the statements of those who have given currency

to the opinion that we may be conveyed at _any_ velocity on railways, are

promulgated by persons who pronounce upon questions without examining

them: since, in addition to this resistance of the _air_ to the

locomotive engines themselves, would be its resistance to the tenders,

and coaches or waggons they drew; and that, too, independent of, and

additional to, the resistance opposed by the _railway_ friction of the

engines, tenders, and loads, behind them.

That something of this kind prevents _very_ high velocities from being

attained on railways, is evident. At the locomotive engine competition

on the Liverpool and Manchester Railway four years ago, velocities of

from 35 to 40 miles an hour, were attained by engines which were not

one-tenth the power of some of those now used; while, at the opening of

that railway, three years ago, the engine by which the surgeon was

brought to Mr. Huskisson, after his deplorable accident, went 15 miles in

25 minutes, which is at the rate of 36 miles an hour. Yet do not the so

much more powerful locomotives now used on that road, go faster than

this: a circumstance which may prove that the limit to the velocity of

railway conveyance, will arise from a source not calculated on.

“But,” it may be observed, “this objection to the possibility of very

high velocities on railways, is counterbalanced by the dilemma in which

you place yourself, by supposing it to be possible that any such power as

that of 29,196 horses, can, at one time, be made to operate on a tunnel;

since, as relates to practical application, it would prove ‘an impossible

quantity.’”

The inference I deny; and, when necessary, will disprove. {41} But the

term I accept; and will avail myself of, to shew that it is equally “an

impossible quantity” that even if a tunnel were ten times as long as one

between Manchester and Liverpool, the friction of air which is caused to

move in it, in consequence of exhaustion taking place at the opposite

end, can ever oppose an impediment such as is here adverted to.

According to the opinion that the friction of the air would increase as

the square of the velocity, the friction of the column of air, which,

when moved by exhaustion at the rate of 20 miles an hour, in a tunnel

eight feet diameter and a mile long, was 288lbs., would, when moved at

the rate of 80 miles an hour, be 4608lbs.; which, on the whole area of

the tunnel, would be equal to 1.3 inches of mercury. Therefore,

supposing that at every mile of a tunnel extending from Liverpool to

Manchester, barometer tubes were to be inserted, the bottoms (or basin

ends) of which should be open to the atmosphere, and the tops open to the

inside of the tunnel, the mercury in each successive tube would

(reckoning _towards_ the end at which the exhaustion took place) rise 1.3

inches higher than that in the preceding.

Now as 1.3×23 gives 30, while 1.3×30 gives 39, it appears that at 23

miles from that end of the tunnel at which the atmosphere was admitted,

and seven from that where the exhaustion took place, there would be such

a vacuum as would raise mercury the _whole_ height of the barometric

column; while, at the end of the 30 miles there would be—or rather

_ought_ to be, according to this calculation—39 inches of mercury; or a

vacuum and a third; which, in addition to its being “an impossible

quantity,” places those who contend that the resistance of the friction

of air which is caused to move through a tunnel by the pressure of the

atmosphere in consequence of exhaustion taking place at the opposite end,

increases according to the square of the velocity, in the dilemma of

assuming that there is a certain place in a tunnel 30 miles long, where,

notwithstanding that a man, a horse, or even an elephant, might walk as

freely and unobstructedly along, as a mouse could through a rat-hole,

that subtle, permeating, and all-pervading element which we breathe,

would, like the stream of the Jordan when under the influence of the

miracle by which the Israelites passed over that river, stop, stick fast,

and be unable to move farther; a position, which necessarily throws us

for an escape from this dilemma, on the conclusion that, though it is

certain that the friction of air against the inside of the tunnel will be

an impediment, and though it is probable that this impediment will be of

some importance, yet must it be equally certain that it will not be the

serious impediment which it is _supposed_ it will prove: and it may

therefore, safely be assumed, that the objection which presents an

insuperable obstacle in the minds of the many who have condemned the

method of operation by exhaustion which I propose (because they deemed it

analogous to operating per plenum) becomes removed, and is found to be

what all the other “insuperable objections” which have been arrayed

against the proposition are found to be when grappled with; i.e. baseless

and unreal: it being necessary only to put a valve at every half, or

quarter of a mile, which should be opened by the carriages as they

passed, to render the length of the column of air of the natural density,

which _must_ be behind the carriages to drive them along, only a few

hundred yards, and its friction consequently unimportant; said valves

being (as can easily be done) so arranged, as to close themselves again

the moment the carriage had arrived at, opened, and passed by, the next

succeeding one.

But though I freely admit that the friction of the air against the inside

of the tunnel may waste power to a degree which shall prove not

unimportant, yet may it be doubted whether it will be more important than

the waste of power occasioned by the present method of railway

transmission by locomotive engines.

In the documents laid before the Lords’ Committees on the London and

Birmingham Railway, by the Treasurer of the Liverpool and Manchester

Railway, on the 28th June, 1832, it is stated that the “number of trips

of thirty miles” performed (or travelled) by the locomotive engines

between Liverpool and Manchester, in the half year ending the 31st

December, 1831, was “5392”: which, as the same document shews that the

_whole_ amount of profitable weight conveyed over those 30 miles during

that half year was less than 91,000 tons, gives an average of only 17

tons as the profitable weight carried each “trip.” The weight of the

engines by which these loads were drawn it may be difficult to fix upon:

though, as the locomotives now used on that railway, are, some of them,

above six tons, others above eight, and others above ten tons in weight,

it may, perhaps, be fair to take eight tons as the average weight. The

weight of the tenders with fuel and water, appears to be rather a

delicate subject. The weight of the tender of the Rocket, with its load

of fuel and water, at the grand locomotive engine competition in October,

1829, was three-fourths that of the engine itself. There have since been

many accounts of immense loads drawn on the railway, of which those by

Dr. Lardner, in his “Lectures on the Steam Engine,” are considered as “by

authority.” But though we find the weights of the engines, as well as of

the loads, and various other particulars (even to the state of the wind)

given, yet does it happen that the weights of the tenders, with their

supplies of fuel and water, are “unascertained” and omitted, throughout.

Under these circumstances, I can do no other than act on the best

information I have obtained, and suppose the weight of the engines and

tenders with their cargoes of fuel and water to be twelve tons for each

“trip.”

Assuming it to be so, the weight of the moving power will be above

two-thirds of the profitable weight conveyed; while, supposing the same

proportion to obtain as to the 4000 tons just mentioned, the amount of

the effect of the friction of the power by which they were conveyed at

the rate of 20 miles an hour, would be twice and a half as much as the

friction of the air would be in a tunnel when twice the tonnage was

conveyed from Liverpool to Manchester in it, at the same rate; which, for

equal quantities, is five times the friction while, as relates to the

fuel consumed, it would be _very_ many more times than this, dearer.

There is one class, who, above all others, might derive benefit from

properly considering what I thus submit, relative to the friction of the

air.

When what was termed “the railway mania” was at its height, it was

calculated that no body of men would be so much benefited by it as the

iron trade; in proof of which the following statement was circulated:—

“We are authorised to state, that the rail-roads already projected,

will require considerably more than two millions of tons of iron.

Now, as iron has recently advanced from 7_l._ to 14_l._ per ton, it

appears that the iron masters (by the way, the originators of, or

principals in, many of these schemes) will receive from the

subscribers twenty-eight millions sterling.”

But, instead of the iron trade having been benefited by the principal

portion of what is expended on railways being for their article, scarcely

more than one-twentieth-part has been expended for iron; the remainder

having gone for labour in “cutting and embanking,” &c. &c.

In the account in Mr. Treasurer Booth’s book, of the expenses of the

Liverpool and Manchester Railway, the line which, in the statement, runs

“Iron rail account,” gives only 66,830_l._ as paid to the iron masters:

the other hundreds, which make up the aggregate of 67,912_l._ there

mentioned, being for “oak plugs, freights, und cartages;” which is little

more than one-twentieth part of the whole that has been expended on this

railway.

The rails of the London and Birmingham Railway are to be half as heavy

again as those of the Liverpool and Manchester Railway. Yet does the

expense of the “rails, chairs, keys, and pins,” in the estimate of that

railway laid before Parliament, amount to only 212,940: one twelfth, that

is, of the two millions and a half, which form the aggregate of the

estimate there given in.

One of the inducements which railway advocates have held out to the

landed proprietors of the Houses of Parliament, in order to lead them to

support railway bills, has been the degree to which poor rates, &c. would

be diminished, in consequence of the labourers there would be employed in

digging out the earth for the cuttings and embankments, in the different

parishes through which the lines of railway would run; and in the papers

of the end of June and the beginning of July (1832) is a _very_ long

advertisement of the London and Birmingham Railway Company, one part of

which states that “The _landed interest_ will be benefitted by the

expenditure of _upwards_ of two millions of the capital of the Company in

labour.”

According to their own shewing, therefore, the expenditure for the

benefit of the landed interest will be “_upwards_ of two millions,” while

the cost of the iron rails, &c. will be only upwards of two hundred

thousand pounds. And as both this, and other advertisements, and the

evidence before Parliament, announce the extension of the railway from

Birmingham to Liverpool, when this first half of it from London to

Birmingham is done—which extension will be about the same length as this

first half—the statements of the railway advocates themselves, give the

iron masters to see, that the result of the time, trouble, and expense,

which they (the iron masters) have devoted to bring forward railways, is,

to put more than a shilling into the pockets of the agricultural interest

(by the degree to which they will save parish rates, &c. &c.) for every

farthing they put into the pockets of the iron masters themselves; all

that is saved to country parishes, being actual gain to the agricultural

interest; while the 12th or 16th paid to the iron trade is for value in

iron; out of which the usual trade profit is all that the iron masters

will gain. In other words, about four millions sterling will be paid

_for_ the parishes between London and Liverpool, in the shape of wages

for labourers, while only about four hundred thousand pounds will be paid

_to_ the iron masters for the iron rails, &c.; out of which the iron

masters will have to pay the wages of their men who smelt &c. the iron,

and the royalties (or rent) for the ore, coal, &c. &c. used in making it.

The difference there is in the specific gravities of ore, coal, and

limestone, in different places, will render any estimate _not_ correct

for every place; though, generally speaking, I believe it may be received

that the quantity of iron stone, coal, and lime stone, which it is

necessary to raise to produce a ton of pig iron, will be about 6½ cubic

yards.

In the evidence laid before the Lords’ Committees upon the London and

Birmingham Railway, it is stated that the whole amount of “earth work”

required for that railway, amounts to 22,779,431 cubic yards; of which a

detailed statement is given in the minutes of evidence.

Dividing the twenty-three (nearly) millions of cubic yards of “earth

work” which are to be excavated and embanked on the Birmingham Railway,

by the number of cubic yards of ore, &c. which it is necessary to dig to

make a ton of iron, will show, that if the wages which will be paid for

levelling on that railway, were to be expended in digging iron ore, &c.

the nation would be benefitted by having three millions and a half tons

of iron more than it now possesses; while the labour expended on the

railway will be not only worth nothing to the nation, but also worse;

insomuch as it appears by the evidence before the Lords’ Committees that

it will render 1250 acres of land, which are now cultivated and

productive, sterile as a turnpike road.

It is supposed by Mr. Treasurer Booth, in his book on the Liverpool and

Manchester Railway, that three thousand miles of rail-road, will,

eventually, be laid down in England.

Supposing these 3000 miles to require “earth work” (cuttings and

embankments, i.e.) in the same proportion that the London and Birmingham

Railway will do so, and also supposing that the wages which will be paid

to the Irish, &c. labourers, who do the digging for this “earth work,”

were, instead, to be paid to the workmen of the iron masters for raising

ore, &c. &c. and converting it into iron, the nation would be richer by

nearly one hundred million tons of iron, than it will be if these said

wages are paid merely for “cutting and embanking” for railways.

Now though I do not mean to insinuate that this hundred million tons of

metallic worth, would increase what is now termed the “monetary wealth”

of the nation, yet, as surely as their ignorance (and consequent want) of

iron, rendered Mexico and Peru such easy conquests to the iron of the

Spaniards, as to make them most striking examples of the truth of Solon’s

warning to Crœsus, “He who has more iron, will soon be master of all this

gold,” so surely would the possession of this hundred million tons of

iron, be enormously more advantageous to the nation, than the cuttings

and embankments required for these 3000 miles of railway will be.

Although iron be not, at the present day, either with ourselves, or in

any other part of the world, the symbol of value, medium of exchange, and

_money_, which Lycurgus made it in Sparta, when that state was in her

glory, yet has it, as a commodity which will obtain us the gold and

silver of Mexico and Peru in exchange for it, a value, which will procure

us the amount of its worth in those metals, as certainly as any other

commodity that we export. In whatever proportion, therefore, this

hundred million tons of iron would procure us either the gold or silver,

the corn and flour, the silks and cottons, the wines and wools, the tea

and coffee, the sugar and spices, &c. &c. of other countries, would

devoting the wages which will be expended in cutting and embanking for

these 3000 miles of railway, to the raising and smelting of iron ore, be

more valuable to the nation at large, than if so employed.

Nor is this all; since the substitute I propose for railways, would give

us food for one hundred thousand people, which these railways will

deprive us of.

The documents laid before the Lords’ Committees, state, that this

Birmingham railway will cover and throw out of cultivation, 1250 acres of

land. Supposing the proportion thrown out by the 3000 miles of railway

to be the same, the whole amount will be 33,333 acres. Allowing these

acres to produce three quarters of corn each, is no very excessive

allowance. {45} And each individual of the kingdom being estimated to

consume a quarter of corn every year, here is land that would produce

bread for one hundred thousand people thrown out of cultivation by the

railway system.

Now as, in addition to its being perfectly _practicable_ for my tunnels

to be buried underground, it would be decidedly best for themselves, and

for the operation of the principle, that they should be so; and as

ploughing, sowing, reaping, mowing, and all other operations of

agriculture, may go on over them, as over any drain, or water-pipe, there

is, in addition to the _metallic_ difference which my plan would make to

the riches of the nation, the circumstance, that, besides providing this

exchangeable metallic wealth, or exportable value, it would also provide

us, every year, with food for one hundred thousand more people, than the

railway system can provide for.

The _metallic_ part of the question being, however, that which concerns

the iron trade, I will keep to that.

One of my early views of this method of conveyance, was, that it _might_

prove important to the iron trade, from the much greater quantity of

their production which it would consume, than railways require: and it

has, for these seven years, been an object with me, to awaken the

attention of the iron masters to (as I conceived) its importance to them,

and to endeavour to convince them of the propriety of giving to a plan,

which would consume _tons_ of their article, where railways consume only

hundred weights, the same fostering and support which they gave to

bringing forward railways.

But it has not pleased the iron masters to see the case in the same light

in which it presented itself to me.

It is well known to them, that in the year 1810 we had neither a

steam-vessel nor a gas-work in the kingdom: the propositions to adopt

both those important inventions being _then_ termed and treated, just as

this proposition of mine is now termed and treated, i.e. as “impossible,

absurd, and madness to think of.” Yet have they seen that a sum of

(roundly speaking) ten millions, has, since that period, been sunk in the

construction of gas-works and steam-vessels.

With proofs such as these before them (and which have led to the

consumption of so much of their production as gas-works and mains

require), that, what they, a few years ago, deemed utterly impossible,

may, nevertheless, be quite the reverse—it might have been supposed that

the iron masters would not prove, either incredulous to, or bigoted

against, the belief that a still more important extension of the use of

their article was about to open to them.

But, to my great surprise, I have found, that of all unbelievers, the

iron masters have proved the most unbelieving.

Other people doubted only because the want of knowledge on the subject,

which they openly avowed, left them no alternative. But, in the iron

masters, I have had “to contend with the pride of false knowledge.” The

world at large said, “We cannot believe, because we cannot understand.”

But the iron masters say, “We do not believe, because _we_ know better.”

On asking them how and why they “knew better,” I found that it was not,

as some might suppose, from any doubt or difficulty as to the tunnel

itself; which they admitted could be cast and laid down, of any size or

dimensions that might be required. Neither was it from any doubt as to

steam-engines or air-pumps being large and powerful enough to do what was

necessary;—the tens of thousands of gallons of air ejected per minute,

from the air-pumps which they use to blow the fires of their

smelting-furnaces, and the hundreds of horses power they know

steam-engines are made equal to, removing all question on these points.

{46} But their incredulity arose from a difficulty which one of them had

met with, in forcing air through a pipe; and of which they supposed me

ignorant; but to which I had adverted, in a publication years before, in

the following words:

“It is too well known, to be at all affected in point of veracity, by

an inability to mention either the exact time or place, that the

proprietor of an iron work in Wales had, some years ago, occasion to

erect an additional furnace, at the distance (recollection states) of

about three-quarters of a mile from his old ones. The blast

apparatus of these old works being large enough to supply this new

furnace in addition to the old ones, he conceived it would prove much

cheaper, if, instead of having power and blast cylinders erected at

the new work, he were to lay a pipe from the old ones, to convey to

the new one the superfluous blast. This he accordingly did; and as

soon as the pipe was completed, set the apparatus going, to ascertain

the strength of the blast he could thus apply to the new furnace. To

his great surprise, however, no blast was produced; a gentle current,

which would hardly blow a candle out, being all that was perceptible.

For a result so adverse to his expectation, he could account in no

way but by supposing that, from accident or design, the pipe was

stopped up. As the readiest way to ascertain whether it was so, he

put a cat in at one end, and blocked it up, leaving her to find her

way to the other.

“Thus situated, puss had no alternative but that of seeking an exit

at the other end: this she accordingly did, and, contrary to his

expectations, soon made her appearance there. Convinced by this that

the pipe was not stopped up, he concluded that the disappointment he

had experienced arose from the friction of the air against it; and

finding that he could in no way obviate this difficulty, he was

obliged to abandon the design, and be at the additional expense of

blast apparatus for his new furnace.

“Now, had the proposition this treatise submits, been, that we should

convey ourselves through a tunnel such as has been adverted to, by

employing apparatus on the principle of blast furnaces, to blow us

through, by _forcing_ air in behind us, the circumstance which has

just been stated would be fatal to that proposition. But when,

instead of being blown through, by air _forced_ in behind us, it is

proposed to cause the air which is behind the vehicle to operate to

push it forward, in consequence of some being taken from before it,

the case is widely different. Air which is forced to move in a pipe,

in consequence of other air being driven into that pipe behind it,

operates (in degree) as a wedge, and opposes to the power which moves

it, resistance, arising from becoming, as it were, wedged against the

pipe, through its whole length. But air which, instead of being

_forced_ to move by an impulse from behind, that, as it were, wedges

it against even the very end of the pipe it enters at, is _allowed_

to move, owing to some being taken out from before it instead of

being forced in behind it, becomes affected as any thing from which a

wedge is _withdrawn_ is affected; that is, freedom of motion is

allowed, and its parts play so much more freely, that friction is

diminished instead of increased. The impediment would prove,

therefore, less important in this case than in the other, even were

there no method of altogether obviating it; happily, however, the

means of doing this are in our power. Between driving a vehicle

through the proposed tunnel by forcing air in behind it, and

according to the method which has been stated, there is this

difference,—that in the former case the impulse can be given only

from the end where the moving power operates; while, in the latter,

arranging valves, which should be opened by the vehicle as it passed

over them, would admit of that impulse being renewed at every hundred

yards, could it be necessary to do it so frequently. Let the

friction of the air against the pipe be what it may, therefore, a

valve at every mile, or at every half or quarter of a mile, which (as

may be done) should be opened by the vehicle as it passed along, and

caused to remain open till it (the vehicle) had arrived at the next

valve, would prevent any diminution of the velocity at which we might

be conveyed, that would prove important.

“This reasoning may be illustrated by a figure relating to an

experiment. Air was forced through a pipe 56 feet long, at the rate

of 20 miles an hour, under a pressure which is equal to 2.2 inches of

water; and as it required a pressure which is equal to 0.6 inches of

water to make air move at that rate through a hole in the side of a

vessel, there was consequently 1.6 inches greater pressure at that

end of the pipe at which the air entered, than at the end from whence

it issued.

“Now if the length of the pipe—the tenths of pressure at the

entering—and those at the issuing end, be expressed by two lines

approximating each other, as shewn below, it may be conceived how

‘air which is forced to move in a pipe in consequence of other air

being driven into that pipe behind it, operates as a wedge; and

opposes to the power which moves it, resistance, arising from

becoming as it were wedged against the pipe, through its whole

length.’”

[Picture: Two lines illustrating the above point]

“Since the length of these two lines bears the same proportion in

hundredths of an inch to 56 feet, as the spaces between the ends of

them bear (in tenths of an inch) to 2.2 inches of water, and 0.6

inches of water; {48a} and if we conceive that forcing air to move in

this way, is, in some degree, analogous to drawing an elastic endless

rope, the size of which should be equal to the larger end of the

pipe, through it, and out at the smaller end, we may form some idea

of the degree to which power would be absorbed in operating by a

plenum. And not only this; since, reversing the operation, and

supposing the rope to be drawn from the smaller to the larger end,

will also give us some idea of the effect of operating by exhaustion,

or vacuum; and enable us to conceive that ‘air which is allowed to

move, owing to some being taken out from before it, instead of being

forced in behind it, becomes affected, as any thing from which a

wedge is withdrawn is affected; that is, freedom of motion is

allowed, and its parts play so much more freely, that friction is

diminished instead of increased.’”