396 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[November, 



adaptcil to a variety of p^irposes, so that they present but little tiniformity. 

 The "Rainbow" anrl the "Glowworm" are celebrated for their speed; 

 their proportions of beam to length are above one to six, and more than three 

 tons to each horse power, which is generally assumed to lie the proper ratio 

 for sea-goins steamers. The tabular statement gives the dimensions and 

 tonnage of tiie vessels, the power of the enjiiies, the proportion of beam to 

 length, and of tons to each horse power, the names of the owners, and the 

 stations where the vessels are plying. 



" On the Stationary Ene/ines n! the netn Tunnel on the Liverpool and Man- 

 chester Jlailway." 15y John Grantham, Assoc. Inst. C. E. 



This communication gives a description of two pair of stationary non-con- 

 densing engines, which were constructed by Messrs. Mather, Dixon, and Co., 

 of Liverpool, from the designs and undi:r the superintendence of the author. 

 The steam cylinders are 25 inches diameter, with a length of stroke of G feet; 

 they have si.le levers like marine engines, but the connecting rods are re- 

 versed, and convey the power downwards to the maohinery, which is placed 

 in vaults cut out of the sandstone rock, upon which tlie beam pedestals are 

 fixed without any framing. Cast iron slides are used instead of the usual 

 parallel motion, and afte^ several years' constant use, they exhibit no marks 

 of deterioration. The drum wheel is 21 feet diameter, and makes usually 

 22 revolutions per minute, when drawing up a train at the rate of 15 miles 

 per hour ; there is a groove in its periphery, at the bottom of which is wound 

 a small cord to form a bed for the main rope to rest upon — tliis main rope 

 encircles about J of the circumference ; it is made of the best Russia heir.p, 

 in three strands, patent shroud laid, the inner strand being composed of JO 

 yarns of white hemp, overlaid by -10 yarns of hemp, tarred to the point of 

 saturation ; this arrangement is found most conducive to the lightness and 

 durability of the rope; its circumference was G inches, and its length, when 

 new, was 4800 yards; in the tirst few weeks it stretched to the extent of 10 

 per cent, of its length, after which it remained unchanged under the tension 

 imposed. The total weight is 8 tons 8 cwt., and the cost was 21. 8s. per 

 per cwt. It is guided by 474 grooved pulleys, 14 inches diameter, and by 

 6 sheaves 5 feet diameter. A new rope will last well for three years, after 

 ■which it is renewed by splicing in a short portion each time, so as to reduce 

 the amount of stretching. 



Inclined plane. — The length of the inclined plane is 2370 yards, at vary- 

 ing gradients; giving an aggregate rise of 77 feet 1 inch, and a mean rise of 

 1 in 92. The tunnel is 2220 yards long. The average weight of the trains 

 drawn up is 55 tons, and the time occupied is six minutes. Tlie pressure of 

 steam is usually from 50tti. to COtb. when the engines begin to wind, and 

 sinks gradually to about 301t). in the reservoir during the time it is working. 

 Power required to draw Carriages up the Inclined Plane. — From some ex- 

 periments made by Mr. Edward Woods, the details of which are given, it 

 lias been ascertained that each pound per square inch pressure of steam upon 

 the pistons over and above the 7'56H). necessary to overcome the friction of 

 the machinery, is capable of drawing one carriage weighing 5 tons gross up 

 the inclined plane. On the first erection of these engines, in order to com- 

 ply with the provisions of an act of parliament, it was necessary to work 

 them with steam generated in boilers, at a distance of 448 yards, and con- 

 veyed through pipes 10 inches diameter, laid in a tunnel excavated through 

 the rock. Several experiments were made to determine the relative amounts 

 of pressure in the boiler and the steam reservoir, and the quantity of steam 

 •which was condensed in a certain time. The results were, that when the 

 engine was standing still, the difference of pressure was about 31b., and when 

 working with a load it was as much as 131b. The quantity of steam con- 

 densed was on an average about 156 gallons per hour. Subsequently, a set 

 of tubular boilers, similar to those of locomotive engines, were erected close 

 to tiic engines, and are now constantly worked instead of those at the great 

 distance ; the economy of fuel has been considerable. The consumption of 

 gas coke ui;der tlie tubular boilers is about 15 tons per week, at ten shillings 

 per ton. The larger boilers consumed about 30 tons ia the same time. 



Mr. Edward Woods gives his approval of the action of the engines, and of 

 the employment of non-condensing engines generally for this class of work, 

 on account of their great simplicity, and the readiness with which they may 

 be brought into full action, so that the greatest power is always at band to 

 start the train ; whilst during the intervals of working the steam may be 

 Buffered to accumulate. These advantages are rarely attainable with con- 

 densing engines, as unless a small engine be employed to keep up the vacuum, 

 there is a difficulty in starting them with tlie train attached to the rope. 



This communication is accompanied liy four detailed drawings of the en- 

 gines and machinery, and by a model of Mr. Grantham's apparatus for regu- 

 lating the admission of steam to the valves. 



Observations. — Jlr. Fairbairn bore testimony to the good quality of the 

 engines and machinery described by Mr. Grantham ; their performance had 

 been very satisfactory. The mode of keeping the rope in tension was an im- 

 provement upon the plan which Mr. Fairbairn had previously adopted at the 

 \Vapping Tunnel, of the same railway, lie would present drawings of that 

 machinery to the Institution. The loss by condensation in long steam pipes 

 is so considerable, that it has been generally found more economical to trans, 

 niit power by a line of shafts, than to convey steam to any great distance, 

 lie had recently constructed some Cornish pumping engines of large size, 

 with side levers and reversed connecting rods ; they had answered extremely 

 well. Drawings and descriptions of theai would be presented to the Insti- 

 tution. 



" On the percussive action of Steam and other Aeriform Fluids." By 

 Josiah Parkes, M. Inst. C. E. 



In a previous communication "On the action of Steam in Cornish single* 

 pumping Engines,"* Mr. I'arkes, after a careful analysis of the ascertained 

 facts of the quantity of water which, in the shape cf steam, passed through 

 the cylinders of the engines, arrived at the conclusion that the steam's elastic 

 force was insufBcient to overcome the resistance opposed to it. On obtaining 

 this remarkable result, he was induced to examine the circumstances under 

 whirh the steam is applied, and was convinced that from the instantaneous 

 and free communication made between the boiler and the cylinder of these 

 engines, an action, distinct in character from the simple pressure of the 

 steam, must be transmitted to the piston. And, in order to convey some 

 precise idea of the peculiar nature of this action, he adopted the terra " per- 

 cussion " to distinguish such action from that due to the simple elastic force 

 of the steam. A'arious phenomena, connected with the working of the en- 

 gine, were adduced in confirmation of the views then advanced. In the 

 present communication Mr. Parkes has resumed the subject, and brought 

 forward numerous facts derived from experiment and observation, on steam 

 and elastic fluids generally, in farther corroboration of his opinions respecting 

 the percussive action of steam in engines. 



The effect of the percussive action of steam may be clearly traced on the 

 indicator diagrams (a series of which, 41 in number, taken from four engines, 

 with differeiit indicators, the pressure of the steam varying from 6'5 to 34.7tb. 

 per square inch, accompanied the communication), and it will be seen that, 

 in every instance, the piston was driven to a greater height than that due to 

 the simple elastic force of the steam ; in many instances a greater pressure 

 was marked than existed in the boiler. The difference in the action, ac- 

 cording as the steam is admitted suddenly, or gradually, into the cv'linder of 

 the engine, may be also distinctly traced on the diagrams. The same effects 

 were observed on the sudden admission of steam upon the surface of raercory 

 in the cistern of a mercurial column. In these experiments, the steam being 

 let on gradually, the gauge marked a pressure of 401b. per square inch, which 

 was the true pressure iu the boiler ; but, being admitted suddenly, the gauge 

 exhibited a pressure of at least BOIb., and the same results were repeatedly 

 obtained. 



The steam generator of Mr. Perkins will afford a good illustration of the 

 effect of the steam's instantaneous action. The pressure in this apparatus is 

 denoted by .".n instrument having an index moving round a dial plate. Steam 

 of 26 atmospheres being suddenly admitted, the index was observed, during 

 repeated trials, to register a pressure as high as 36 atmospheres, and then to 

 recede until it remained stationaiy at 26 atmospheres, which was the pres- 

 sure in the generator. The results of these various experiments are arranged 

 in two tables, exhibiting an analysis of the elements into which they may be 

 resolved. 



The author then proceeds to point out the different circumstances of the 

 pumping and crank engines, in respect of their realizing, beneficially, the 

 steam's percussive action. In the latter, this instantaneotis action takes 

 place (as the indicator diagrams show) when the connecting rod and crank 

 are in one vertical line, so that it is inefficiently expended ; the centre, by 

 the agency of the fly wheel, not having been passed. In the former, the 

 load and fiictional resistance alone oppose the descent of the piston ; the 

 piston is free to move, and the steam's action is wholly efficient in impelling 

 it ; and, whatever the amount of the percussive action, it will be accounted 

 for in the effect. 



A remarkable confirmation of the conclusions arrived at, and the views 

 advanced by Mr. Parkes in his previous communication, bad been furnished 

 by Mr. W. West. The cylinder cover of the Fowey Consols engine, 80 

 inches in diameter, and weighing 4 tons, springs upwards at the centre -150 

 of an inch, on the sudden admission of steam, which in the boiler has a pres- 

 sure of 49'7tb. ; and i of an inch, the steam in the boiler being Gl'71t). ; but 

 no change of form, or springing, occurs when the steam is let on gradually, 

 and fills the cylinder at the same pressure as that in the boiler. 



The author adduces many other facts in illustration and confirmation of 

 his views ; as, the oscillation of the mercury in steam and vacuum gauges; 

 the audible sounds produced in a steam pipe on suddenly checking the mo- 

 tion of the elastic fluid by shutting a cock ; the curious phenomena connected 

 with the impact of elastic fluids on each other, particularly those observed 

 by Mr. Greener on firing gun-powder in long open-ended barrels; and, in 

 conclusion, suggests whether these remarkable facts may not serve to assist 

 in elucidating some of the very difficult and apparently inexplicable phe- 

 nomena, connected with the explosion of steam boilers. 



Remar/ts. — Mr. Lowe had recently made some experiments, which in his 

 opinion confirmed Mr. Parkes's views on this interesting subject. A pressure 

 gauge, attached to a line of gas pipes, showed, when the communication was 

 slowly opened, a pressure of four inches column of water; but it invariably 

 exhibited a maximum of oscillation of full six inches column on the sudden 

 opening of the small stop-cock between the pipe atd the gauge. In aline 

 of pipes, full of gas, the whole volume of gas received an impulse on suddenly 

 opening the valve at one end, and the passage of the undulating wave was 

 indicated by the sudden and successive depression of the water in the gauges 

 along the whole line. 



Mr. Uomersham could not agree with Mr. Parkes as to the effect due to 



* Sec Transactions Institution C. K., Vol. III. 



