1843.] 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



407 



The plan of workine bv liydraulic propulsion now propose<l, which 

 is detailed at ereat length in the pamphlet before us, has effected a 

 complete change in the mode first intended. Mr. Shuttleworth bow 

 relies entirely ?or the propulsive power on the pressure of a column 

 of water, acting against the pressure of the atmosphere, without any 

 exhaustion. He proposes to have reservoirs of water, of sufficient 

 height to produce a pressure of six atmospheres, placed at short dis- 

 tanfes along the line of railway. From these reservoirs vertical pipes, 

 of the same diameter as the horizontal, are to convey the water to the 

 commencement of each section of propulsive piping. The length ot 

 each of these sections is to be about "0 or SO yards, and the termi- 

 nation of each section of propulsive piping Mr. Shuttleworth pro- 

 poses to connect with double its length of what he terms skeleton 

 piping," along which the railway carriages are to be propelled by 

 the momentum previously acquired. In the intervals between the 

 rsnning of the trains, it is proposed to employ stationary engines of 

 ereat power to pump the water back again to the elevated reservoirs. 

 The foregoing is an outline of the principal features of the hy- 

 draulic railway. The advantages which are expected to result from 

 its adoption are, diminished cost in the mode of working, increased 

 safetv, by the avoidance of collisions, and greater facility in the con- 

 struction of railways in hilly countries. Mr. Shuttleworth makes 

 various calculations for the purpose of showing the economy of his 

 system of propulsion compared with that by locomotive engines; but 

 into these details we do not propose now to enter. Our present pur- 

 pose is to examine the principles on which he founds the hydrauUc 

 mode of propulsion; for if these prove to be defective, as we believe 

 them to be, it will be useless to inquire further. 



The first great error into which we conceive Mr. Shuttleworth has 

 fallen, is in the calculation of the initial velocity that could be com- 

 municated to the carriages by a vertical column of water of the same 

 diameter as the horizontal pipe. He professes to take all his data 

 from the best authorities in hydrodynamics, among whom Mr. 1 red- 

 gold ranks foremost, and it is only due to Mr. S. to say that he claims 

 no more in favour of his plan than the calculations of the authorities 

 he relies on seem to warrant. His fault, like that of many other in- 

 genious inventors, lies in the attempt to apply general principles to 

 particular circumstances wherein those principles are inapplicable. 

 Founding on Mr. Tredgold's formulae, Mr. Shuttleworth estimates the 

 velocity of water rushing from the bottom of a column 198 ft. high 

 to be equal to G7t miles an hour; this, therefore, he assumes to be the 

 initial velocity which might be communicated to the train of carriages 

 on the hydraulic railway. Now, granting that water would rush from 

 a small aperture at the bottom of such a vertical column with a velo- 

 city of 67f miles an hour; we cannot concede that the whole column 

 would rush out wilh that velocity. According to theoretical estimates, 

 water rushes from an orifice with the velocity whicli a body falling 

 freely would acquire in moving through a space equal to the height 

 of the water above the orifice; but many circumstances may cause 

 the velocity of the issuing fluid to deviate from this general law. If 

 ■the size of the aperture approximate to that of the tube, the velocity 

 will be diminished; and if the aperture be of the same size as the 

 tube, so that the whole column of water must fall as rapidly as the 

 issuino- fluid, the velocity will be diminished one half, without 

 raakin'g any allowance for friction. That this must be the case will 

 appear from the circumstances attending the fall of a column of any 

 other body the particles of which cohere. The accelerated motion ac- 

 quired by all bodies in their descent, would naturally give to the water 

 towards the bottom of the vertical pipe a much greater velocity than 

 to the water at the top ; and were the particles of the fluid without 

 cohesion, they would separate into drops in their fall, instead of 

 acting in one connected column. The cohesion of the particles is, 

 however, sufficient to prevent this separation, and the fluid column 

 must, therefore, move with an uniform velocity, in the same manner 

 as a chain or a rope thrown over a pulley must fall throughout its 

 whole length with uniform velocity. The lower portions of the water 

 or chain which, if detached, would move with greatly accelerated 

 velocity, are retarded in their descent by adhering to the more slowly 

 raovin" portions above, to which they in turn impart some of their 

 superior momentum gained in the descent. The communication of 

 velocity from the lower portions of the falling column to the upper is 

 evidenced in the flow of water down pipes, by the force with which 

 the water in the reservoir is drawn into the pipe ; which force in- 

 creases with the height. It thus appears, that the resulting velocity 

 of a vertical column of water must be the average motion given by 

 gravitation to the whole ; or less than half that which Mr. Shuttleworth 

 calculates would be the initial velocity in his system of propulsion. 

 He might, it is true, obviate this difficulty by greatly enlarging the 

 size of the conduit pipe, but this would materially add to the cost of 

 construction. 



Another important error appears in Mr. Shuttleworth's calculations 

 in consequence of the velocity of water flowing freely being consi- 

 dered the measure of its propulsive effort. Now, it is very obvious, 

 that any effort required to propel the train of carriages on the railway- 

 must diminish the velocity of the acting fluid ; and that in proportion 

 to the velocity communicated to the train, the propulsive effect of the 

 fluid pressure must diminish ; for it is only when the pressure is re- 

 sisted that its effect operates. For example; if the carriages were 

 propelled by some other power at a velocity equal to that with which 

 the water rushed along the horizontal pipe, the fluid would evidently 

 exert no impulsive effort on the piston. If the carri;ige3 were pro- 

 pelled wilh half the velocity of the fluid, then only half ilie impulsive 

 effort would be exerted ; and not until the train was stationary, would 

 the full pressure of the fluid be bronglit to bear on the piston. The 

 whole of Mr. Shuttleworth's calculations of the power to be derived 

 from hydraulic propulsion would, consequently, only apply to pressure 

 against a stationary resistance : so soon as the train was put in motion 

 the power exerted on the piston would diminish and would continue 

 to decrease in proportion to the increase of speed attained. 



One of the objections urged against the system of propulsion by- 

 locomotive engines is the great waste of power occasioned by the 

 weight of the engine and tender, yet Mr. Shuttleworth seems to have 

 entirely overlooked the fact, that the same objection applies, in a ten- 

 fold degree, to his plan of hydraulic propulsion. He has, indeed, no 

 heavy engine to propel, but the weight and friction of the water, 

 which constitutes his moving power, offer a far greater resistance to 

 motion than an engine and tender. The length of each section of 

 propulsion piping is proposed to be only 70 yards, yet towards the 

 end of that short length the weight of water to be propelled would 

 amount to nearly 5 tons. This weight of water would have to be 

 put in motion vvith great velocity, with the additional objection of 

 being exposed throiigfioitt Us whole coune to retardation by friction in 

 the pipe ; whereas the frictionof a locomotive engine acts only on those 

 points of the rails whereon the wheels rest. The loss of power by- 

 retardation in the tube is, indeed, taken into account by Mr. Shuttle- 

 worth, but he appears to overlook the fact that this loss is occasioned 

 by communicating motion to his moving power. The amount of 

 power lost by propelling the water through the pipe is much greater 

 than would at first be supposed. Mr. Shuttleworth himself estimates 

 that his calculated initial velocity of 67j miles an hour would be 

 reduced in a length of pipe of only 70 yards, to 29f miles an hour; 

 and in another part of his pamphlet it appears that the estimated 

 initial propulsive power of G'j3 horses (!) vrould be reduced, after 

 passing through 70 yards of piping of one foot diameter, to 71 H. p. 

 We have thus, by Mr. Shuttleworth's own showing, a power of G22 

 horses absolutely lost in propelling the moving power; and that too 

 for the short distance of only 70 yards! Surely no system of railway 

 propulsion was ever before proposed, which by the statement of its 

 inventor exhibited such a waste as this; and yet it is proposed as a 

 means of economizing power! 



Nor is this all. An enormous waste would arise also from the at- 

 tempt to regulate the speed communicated by a power varying, by the 

 estimate, from G93 horses to 71, in the space of 70 yards. To obviate 

 the objection which would be urged against the plan, were the rates 

 of speed to be so unequal, Mr. Shuttleworth proposes to fix a self- 

 acting throttle-valve at the commencement of each section of_pro- 

 pulsion piping, so as to reduce his estimated initial velocity of 67^ to 

 27 miles an hour. Thus nearly two-thirds of the power would be 

 absolutely thrown away for the' purpose of regulating the speed to 

 agree with that of the terminal velocity of the water. Mr. S. appears 

 to imagine, however, that this check on the flow of the water, would 

 not diminish the pressure, because, according to the laws of hydro- 

 statics, the pressure is as the base of the resistance, and that the area 

 of the piston would therefore sustain the same pressure however 

 small the opening of communication from the vertical column of 

 water. He forgets that this law obtains only in fluids at rest; and 

 that as soon as the piston moved under the impulse of the whole ver- 

 tical column of water, the impulsive force would be diminished. If 

 the throttle-valve were so regulated as to reduce the velocity to 27 

 miles an hour, the pressure on the piston would correspond with that 

 velocity, and not with the pressure of the whole vertical column. All 

 the force lost by checking the water at the throttle-valve would con- 

 sequently be so much power wasted. 



Jt might be supposed from the lavish waste of power which is ex- 

 hibited throughout the whole plan of the hydraulic railway, that the 

 inventor had at command the falls of Niagara every 200 yards of his 

 proposed line ; the waters of which he could send rushing through 

 the pipes without any limitation. Not so, however, for every drop of 

 water thus uselessly squandered is to be forced back again into arti- 

 ficial reservoirs. Of these reservoirs, indeed, though theyforni an 



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