204 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[June, 



<?argo and passengers, the other only the engines and fuel, yet the " Great 

 Western" travelled farther with the same quantity of fuel. 



Table showing tlic power rc(iuired to obtain various rates of speed in a 

 steam vessel, where the total weight of cargo and engines remains in all cases 

 the same, and in which, with a power of 30 horses, a speed of a miles per 

 hour is obtained; the total weight carried being in all cases 1000 tons, and 

 the engines weighing 1 ton per horse power. 



In answer to a question relative to American steam boats, he believed that 

 the build of the river steamers was very peculiar : some of them had engines 

 of 600 horses power on board, yet they drew only four feet of watei-, whereas 

 a sea-going steamer with that power would dr^.w at least 16 feet. As far as 

 he could ascertain, the actual well-authenticated speed did not exceed 14J 

 geographical miles per hour through still water. The fuel consumed could 

 not 1)0 ascertained, as it was chiefly wood, taken on board at the places of 

 stoppage ; there was a great consumption of steam at a very bigli pressure. 

 Their machinery was not lieavy. and was specially adapted to the vessels. 

 Daily improvements were making in the form of vessels in England, and 

 when high pressure steam and light engines were applied to vessels of a dif- 

 ferent form from those at present constructed, the speed must be increased. 

 Some vessels w-ere now building on the Thames of an extremely light con- 

 struction, with tubular boilers, and the weiglit of the machinery would be 

 only eleven ewt. per horse power. 



February 16. — The President in the Chair. 



The following were balloted for and elected: William Eadford, Henry 

 Alexander. John Gandell, William Bagnall, Thomas Bagnall, and James Bag- 

 nail, as .\ssociates. 



" Pra-.tical Observations on the management of a Locomolvoe Engine." By 

 Charles Hutton Gregory, Grad. Inst. C.E. 



The working of a railway involves a number of practical details with which 

 it is of great importance that the yomig engineer should make himself 

 thoroughly acquainted. Of these, one of the most important is the manage- 

 ment of a locomotive engine. 



The communication consists of practical remarks on this subject from the 

 author's individual experience; it is divided into three sections :— 1st. The 

 management of an engine in the Station. 2nd. On the Road. 3rd. In cases 

 of accident. 



Section 1st— contains instructions as to the state in which an engine should 

 be kept in the station, and a detailed account of the examination to which it 

 should be subjected previously to its starting with a train. The principal 

 working parts are mentioned, with the particular attention due to each ; and 



the jiroper supplies of oil, coke, and water, enumerated. The section con- 

 cUules with a list of the articles necessary to be carried on the tender. 



Section 2nd — enters fully into the leading points of engine driving. After 

 attending to the precautions to be taken in starting, the aotbor points out 

 the proper position of the engineman, and the attention which he should give 

 to the state of the rails, the safety of the train, and the working of the engine. 

 Instructions arc then given for the production and maintenance of a sufB- 

 ciency of steam, by the judicious management of vater and/«e/. The proper 

 heielit of the water in the boiler is described both under general and parti- 

 cular circumstances, and the times at which it should be supplied: with ob- 

 servations on priming, on the action of the pumps, and their irregularities. 



This is followed by remarks on the proper manner of supplying coke, the 

 extent and periods of that supply, the proper height of the coke in the fire 

 box, &c. 



Instructions are given for economizing and rendering the steam most effi- 

 cient ; the mode of treatment to be adojjted in case of extraordinary deficiency 

 or excess ; rules for stopping and starting at the stations; general hints in 

 case of the wheels slipping, and of the heating of the axles ; precautionary 

 measures to be adopted on curves, steep inclines, dangerous parts of the road, 

 &c. ; the care necessary for an engine at the end of each journey, and when 

 finishing its work for the day. 



Section 3rd — describes those accidents to which engines are most liable 

 when running, and the steps to be taken under the circumstances : viz. — The 

 bursting of a tube, the lagging of the boiler catcliing fire, the failing of the 

 feed pumps, the breaking of an axle, of a spring, or of the connecting rod, 

 the disconnexion of the piston, of the eccentrics, or any of the slide valve 

 gear, the fracture of the strap of the slide valve, and the engine running off 

 the rails. 



" Observations on the effect of wind on the g>isj)ension bridge over the ilenai 

 Strait, more espccial/g with reference to the injuries which its roadways sus- 

 tained during the storm of January 1839." By W. A. Provis, M. Inst. C.E. 



In the month of December 1825, when the original construction of the 

 bridge was nearly completed, several severe gales occurred, and considerable 

 motion was observed, both in the main chains and in the platform of the 

 carriage ways. It appeared that the chains were not acted upon simultan- 

 eously, nor with equal iutensity ; it was believed, therefore, that if they were 

 attached to each other, and retained in parallel plains, the total amount of 

 movement would be diminished. 



On the 30th of January, and on the Gth of February, 1826, some heavy 

 gales again caused considerable motion of the chains and roadway, breaking 

 several of the vertical suspending rods, and of the iron bearers of the plat- 

 form. 



These bearers were constructed of wrought iron bars, overlapping each 

 other, and bolted together, with the ends of the suspending rods between 

 them, for the purpose of giving stitfness to the structure. Tlie flooring planks 

 were bo'.tcd to the bearers, .-.nd notched to fit closely round the suspending 

 rods, which were thereby held almost immoveably in the platform. 



It was observed, that the character of the motion of the platform was not 

 that of simiile undulation, as had been anticipated, but the movement of the 

 undulatory wave was oblique, both with respect to the lines of the bearers, 

 and to the general direction of the bridge. It appeared, that when the sum- 

 mit of the wave was at a given point on the windward side, it was not colla- 

 teral with it on the leeward side, but, in relation to the flow of the wave, 

 considerably behind it, and forming a diagonal line of wave across the plat- 

 form . 



The tendency of this undulation was, therefore, to bend the bearers into a 

 form produced by the oblique intersection of a vertical plane with the surface 

 of the moving wave. The bearers were not calculated to resist a strain of 

 this nature : they therefore were fractured generally through the eyes on each 

 side of the centre foot-path, at the point of junction with the suspending 

 rods, which being bent backward and foi-wards where they were held fast at 

 the surface of the roadway, were in many instances wrenched asunder also. 



The means adopted for repairing these injuries, and for preventing the re- 

 cnrrence of tbeni, were, placing a stirrup, with a broad sole, beneath each of 

 the fractured hearers, attaching it by an eye to the suspending rod, cutting 

 away the planking for an inch around the rods, and at the same time bolting, 

 transversely, to the underside of the roadway, an oak plank, fifteen feet long, 

 between each two bearers, for the jjurpose of giving to the platform a greater 

 degree of stiffness, comliined with elasticity, tlian it previously possessed. 

 The four lines of main chains were also connected by wrought iron holts 

 passing through the joint plates, and traversing hollow cast iron distance 

 pieces, placed horizontally between the chains. 



The effects of these alterations were so beneficial, that little or no injn y 

 occurred for nearly ten years. On the 23rd of January, 1836, a more t'lan 

 usually severe gale caused violent undulation of the platform, and broke 

 several rods. There can be little doubt that ten years' constant friction, 

 comljined with the shrinking of the timber, had relaxed the stift'iicss of the 

 platform, and permitted an increased degree of undulation. The gate-keeper 

 described the extreme amount of rise and fall of the roadway in a heavy gale 

 to be not less than sixteen feet ; the greatest amount of motion liciiig about 

 half way between the pyramids and the centre of the bridge. 



In consequence of the injuries sustained during this gale, the author and 

 Mr. Rhodes were instnicted to give in a report upon the state of the bridge, 

 and on any repairs or additions which might appear desirable. 



