120 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[March, 



IMPROVED TWO CYLINDER ENGINE. 

 ( With an Engraving, Plate IF.) 



Description of a 20-horse high pressure engine, with two cyh'nders, 

 in the establishment of Messrs. Geo. Forrester & Co., Liverpool. 



This engine is represented in the accompanying engraving ; Fig. 1, 

 being a side elevation; Fig. 2, a ground plan; and, Fig. 3, an end 

 view of the same. 



The improvement consists in an arrangement of tno cylinders (in- 

 stead of one of double the area), which are placed side by side upon 

 an independent foundation plate, in a horizontal position, with a space 

 of sufficient width to allow a connecting rod to work freely between 

 them ; the piston rods of both cylinders are connected together by a 

 cross-head at one end, from which the power of the combined cylinders 

 is communicated directly by a long connecting rod to the crank shaft 

 at the other. Each cylinder is provided with a separate slide valve, 

 both valves being connected together, and worked by one valve shaft 

 and eccentric motion. The feed pump is placed at the front end of 

 the foundation plate, at the same level as the cylinders, and is worked 

 directly from the main cross head of the engine, to which the pump 

 ram is attached. Steam of 35 lb. pressure is used in the boiler, and 

 the supply is regulated by an atmospheric governor (Hick's patent), 

 which is attached to the throttle valve, placed in the leading steam 

 pipe to the two cylinders (as shown in the drawing). 



The object of the above arrangement (as will be seen) is to lessen 

 greatly the dimensions and vveight of the engine, the length occupied 

 being little more than half that of the ordinary engine, whilst all the 

 working parts are rendered more accessible, and their simplicity is 

 such as to render it both durable and easy of attention. An important 

 feature in this arrangement is that of the crank shaft being very close 

 in position to the seat of the cylinders, whereby the strain of the 

 engine is confined to a very limited portion of the foundation plate, 

 the power of the combined cylinder not being transmitted through 

 any portion of the framing at their front end, but only through that 

 part intervening between them and the crank shaft which is placed 

 immediately behind them. The engine being thus perfectly self-con- 

 tained requires no foundation, except a bed of brickwork or timber to 

 raise it to the requisite height, whilst the reduced space it occupies 

 renders the expense of the engine house, or preparation for it, com- 

 paratively small. 



KEVlEWa. 



GEOLOGY. 



1. Geology, introductory, descriptive and practical. By David 

 Thomas Ansted, M.A., F.R.S., Professor of Geology in King's Col- 

 lege, London. Loudon: Van Voorst, 1844. Part L 



2. A History of British Fossil Mammalia and Birds. By 

 Richard Owen, F'R.S., Hunterian Professor at the Royal College of 

 Surgeons. London: Van Voorst, 1844. Part I. 



The study of geology, whatever interest it may possess for the 

 follower of abstract science, has immediate claims upon the engineer, 

 being intimately connected with his practical pursuils, and recognised 

 as an imperative part of his professional course and taught in the 

 public schools. In the design of grand works of internal communi- 

 cation in tlie drainage of the opt-ti country, in the search for water, 

 in the industrial application of the miupral resources of a district, 

 the engineer experiences the necessity fur a well grounded acquaint- 

 ance with the principles and details of geology. In the laying out 

 of a line of canal or railway, he must ascertain what materials he has 

 in the locality, which can be used with a due regard to economy and 

 durability, and from inattention it has often happened that materials 

 have been at much expense brought from a distance, which were to 

 be found in equal abundance and perfection on the spot. It lies with 

 the skilful engineer to point out such deposits of brick earth, lime, 

 ballasting sand, and other mineral prod uctions as may become a source 

 of increasing traffic to the line. For the supply of a steam engine or 

 factory he will frequently find a difficulty in obtaining the requisite 

 supply of water, and he has to determine on the practicability of ob- 

 taining it from the underlying strata. He may also have to construct 

 absorbent artesian wells, for the purpose of carrying off impurities. 

 Jn the supply of water to large towns, geological knowledge is of 

 much avail, for the engineer has not merely to avail himself of sur- 

 face sources, but he must ascertain how far the supply of water is 



likely to be permanent, 'and what means exist of increasing the sur- 

 face supplies. He may also be threatened with opposition as inter- 

 fering with the supply of water to other purposes, and to vested in- 

 terests. The question of bringing water from the Colne, so ably dis- 

 cussed by Mr. Robert Stephenson, was mainly one of geology, (Civil 

 Engineer and Architect's Journal, Vol, VI., p. 350.) In the course 

 of works, too, many geological questions arise, not merely as to the 

 nature of the substrata influencing the foundations and the power of 

 sustaining an embankment without bulging or spewing, or as to the 

 extent of a deposit of wet sand or quicksand, but in a variety of ways. 

 Thus in the important case of Ranger v. the Great Western, one of 

 the allegations was that a particular rock was improperly and unfairly 

 described, the description of Pennant stone intimating that it was a 

 soft rock, whereas it was a hard rock, and that the trial pits on one of 

 the sections were unfair, because they did not show the substratum of 

 hard rock, and of which no mention was made in the specification, 

 whereas it ought to have been known to the engineers that such a 

 substratum was to be found within a certain depth, and that thereby 

 the contractor was misled. In this specific instance judgment was 

 given in favour of the engineer; but it shows how much care it be- 

 hoves the practitioner to employ. Indeed the geological features 

 often influence a contract; bricks are directed to be made on the spot; 

 thus Mr. F. W. Simms, C.E., had the superintendence of a tunnel, 

 constructed on the South Eastern Railway, through a difficult geolo- 

 gical formation, and at the same time he had the direction of large 

 brick works in which he introduced several valuable improve- 

 ments, (Civil Engineer and Architect's Journal, Vol. VL, p. 348.) 

 The use of stone upon the line requires a good deal of conside- 

 ration, and also the use of any material for embankments, or bal- 

 lasting. The danger of mixing some sells is well known, witness 

 the case which occurred some time ago of pyrites taking fire on 

 the London and Birmingham Railway, and embankment, sleepers, 

 and rails being seriously injured. The use of light sand employed on 

 the Croydon Railway for some time until gravel could be reached, 

 was found highly inconvenient for ballasting, the passengers com- 

 plaining much of the quantity blown into the carriages, and the main* 

 tenance of the line being very troublesome. An intimate acquaint- 

 ance with the different strata is in fact of the greatest importance, 

 one material will stand with one batter, one with another, and so on, 

 and an engineer removed from one geological district to another, will 

 often find himself at a loss, when he attempts to avail himself of bis 

 previous experience in his new locality. Thus a northern engineer 

 will frequently not duly allow for the nature of the chalk and London 

 clay formations of the southern districts. Tunnels are projected in 

 the chalk as a homogeneous and compact mass, and fissures are met 

 with, and springs of water. The London clay, too, presents the 

 greatest difficulties, and baffles all calculation; works may stand very 

 well for two or three years, or for longer periods, then they swell with 

 water, extensive and sudden slips take place, and there are no means 

 of stopping them. It cannot be said that the slips on the Croydon 

 Railway are yet remedied; and certainly Mr. Gibbs was as little to 

 blame for their occurrence, as Mr. Cubitt is for not having been able 

 yet to check them, although so much of the clay has been removed, 

 and large buttresses of gravel have been substituted. So at last the 

 London clay has begun to show its character in the Camden Town 

 cutting of the London and Birmingham Railway, and Mr. Watson's 

 ingenious plan of draining (described at pages 49 and 61 of the pre- 

 sent volume) has been obliged to be adopted as the only efficient 

 means of checking the evil, though strong retaining walls strengthened 

 by iron girders, present a barrier sufficient to contain any other mate- 

 rial. The treatment of slips has become a new branch of engineering, 

 requiring a most skilful application of the various modes and appli- 

 ances of draining, while as yet the means of so constructing the 

 original works as to prevent slips is far from being in a satisfactory 

 state. The engineer avails himself of previous experience, he finds 

 works standing in several localities with a certain batter, and yet his 

 own works may crumble to the ground, though he has faithfully fol- 

 lowed the exemplar. One element with regard to the slope, at which 

 any material will stand, has, in our opinion, beeu passed over, and 

 that is the height. It may happen that clay or chalk may stand very 

 well with a certain batter at 20 ft. high, and yet that it may not stand 

 with the same batter at 40 ft., 60 ft., or 80 ft. We think it very 

 likely that a law prevails modifying such results, and it would be very 

 desirable to have the subject investigated. 



We need scarcely allude to the advantages which an engineer will 

 derive from his geological knowledge in laying out any grand line of 

 works, the adoption of such a course as to avail himself of the natural 

 passes and levels, and not to come in contact with the natural difficul- 

 ties. So too with regard to many operations; thus the grand experi- 

 ment of Mr. Cubitt iu removing large quantities of the Dover chalk 



