IfiS 



Tiiii; CIVIL engtni:i:r am) aikiiitect.s journal. 



[May, 



the loail awav. clearing out a bay, wliieli, from iiieasiiremeiit, we liiid about 

 the perpendicular length of the groyne, which was the passive cause of the 

 inroad. Had the groyne in (picstion not been erected, althongh the wall 

 woidd have been undcrniiiied and tlirown down by the grovne farther west, 

 at the South Saxon hotel, yet the inroad would have been Icks considerable ; 

 or had the ctl'ccis of our niini.itnrc promontory been dindnishcd, by couslnict- 

 ing it on a smaller scale, anil ueutraliziug its mixrhieruiix tendency by a well 

 graduated lijie of groynes to the eastward, the inroad would have been pre- 

 vented. Croyncs on this pan of Ihe coast arc well Known to have the clfeet 

 of saving and )n-otccting land to the westw.ird, and of endangering il unless 

 the groynes be continued to the eastward; this any common observer would 

 satisfactorily demonstrate to " E," and in explaining tlie grand alterations in 

 the face of ihe coast, by reference to such ndniature causes, we lielievc, our 

 views are unquestionably snbstantiateil, as far as the encroaebnicnls of the 

 sea arc concerned ; and we arc efpially conliilcnt in the accuracy of our views 

 with respect to the recessions of the sea, that they occur in i)roportion as 

 the headlands, which, nndcr the agency of the prevailing current, formed 

 bays, are dindnishcd. This would, we belic\e, be experimentally proved if 

 the groyne, which has caused the injury to the esjilanade wall at St. Mary 

 Magdalen's, were reduced in length and height. The sea would throw up 

 heacli wlLCre it has recently invadcil, and there it woidd remain to an extent 

 exactly proportioned to the ilinunulion of tlic weslerly groyne or headland. 

 Similar reductions have taken jilace in groynes farther to the eastward, which 

 had been constructed on too large a scale, and their destructive tendency to 

 the eastward thereby reduced in a direct ratio. With these facts, supporting 

 the theory we have advanced for the general cause of the encroachmeuts and 

 recessions of the sea, we must, mitil " E " succeeds in shaking our data, 

 instead of merely questioning them, assume that we ha\e ottered a satisfac- 

 tory ex|danation of the interesting phenomena afforded Ijy the alteration of 

 the Southern coast, and, in couc-'usion, express a conviction that if 13eachy 

 Head and tlie Hastings cliffs were severally extended to the distance sea- 

 ward tliat now exists belweeti Pevensey castle ami the sea, ami also between 

 Winchelsca,'- and the present high-water mark, such an elongation of the 

 obstructing headlands would give such an additional impetus to the sea, as 

 to cause it again to wash the base of the hills on which those towns are 

 situated. We have affirmed tliat the per|ienilieular line, from the onliuary 

 high-water mark to the furthest discernible inland existence of beach, is equal 

 to the original projection of the headlands beyond their jiresent termini, and 

 we believe it to lie correel. We, however, invite inquiry on the sidjject, as 

 also to the cause of the rei/iilnr hiyh-vater marhs successively following each 

 other for a consiilerable distance on Lydd beach ; the early ones being covered 

 with green sward, evidently the produce of ages. 



RESISTANCE TO RAII.M'AY TRAINS. 



T)i\ I.arihier rcccnlli/ ihlh'eivil at ihe Atlienii'vm, Manchester, a eourse of 

 lectures " On the resistance ofraitieay trains, the effects of gradients, and 

 ihe i/cnerul economy of steam power." 



Lecture I. 



Dr. Lardner commenced by observing, that it was a strong examjile of the 

 manner in which practical matters were conducted in this country, that they 

 liad been now ten years, with all the extraordinary effects of railways passing 

 under their notice, stinmlating their attention and calling up the wonder of 

 all parts of Europe, and yet to this hour the general jiroblem, the solution of 

 which was the actual amount of resistance to railway trains, nught be con- 

 sidered to remain, so far as the engineering profession was concerned, with- 

 out solution. 



It was not till a very recent period that, even on common roads, the 

 auunuit of this resistance had been made the subject of inquiry. An instru- 

 ment bad, however, been invented by Mr. M'Ncil, the engineer, who had 

 instituted experiments to ascertain the actual resistance on turnpike roads, 

 which he had fouml to be about one thirtieth jiart of the load. Now, the 

 ])rinciple was ccpially applicalile to common roads as to railways, that the 

 resistance ^von]d be diminished in the proportion in which they enlarged the 

 wheel ; but when they increased the si/e, they also iiu'reased the weiglit, so 

 that there was a jiractical linut to the dinnnisbiug of resistance in this nuin- 

 ner. The average resistance which a load ]tlaec<l on a raih\'ay offered lo the 

 tractive ])Ower, was intiniafely comieeted with the principle n))on which rail- 

 Wiiys themselves were constructed ; and this connexion had been largely 

 acte<l n]>OM by the legislature in all incjuirics concerning contested railway 

 bills. It ha<l been assumed in jiarliament that an engine luight be expected 

 to jiull a load, with all the necessary ex]»edition, u)i an inclirted plane, pro- 

 virled thai inclined jilane olVcreil not more than double the resistance which 

 tlie engine had op])Osed to it on a level. That had been laid down and acteil 

 upon in parlianu'ut as a species of standing order. The principle acted upon 

 was, that the resistance upon a level wotdd be abocd !l ll.s. a tcui, and, conse- 

 queidly, an inclination which resisted 1 in 2.')0, was an incliuatifm u)) v\hich 

 the engine might be expected to work with a full speed. Upon this princiiile 

 the sections of all Ihe railways in the country had been laid. But the fact 

 was, that the resistance depended upon eiilirely difi'erent principles. In the 



' Both places are said to have been .washed by the sea.— Vide map, &c., 

 " Camden s Britannia." 



iuijniricj which took place, no one ever hinted that the resistance depended 

 upon the sjieed — no one suspected for a nmnient that there was more resist- 

 ance at thirty miles an hour than at one nnle an hour. He was quite sure 

 that many would be perfectly astonished at this statement, but it was a fact 

 established by abundant evidence, and injunncrable experiments made by 

 pbilos()l>hers at ditfereut times and in dltfci'cnt countries, that resistance de- 

 pcmltMl upon friction, and did m)t dcpcml \\\y»\ speed ; that so far as resist- 

 ance to any degree depends iqion the friction of the axles upon their bear- 

 ings, or the rolling motion of the fires upon the road, it was demonstrable 

 that the resistance was the same at all speeds whafevi'i-, whether twenty, 

 thirty, fortv, or fifty miles an lioiu" Never supjiusiiig there was any other 

 cause, they at once assumed that resistance, at all speeds, was cither .actually 

 or nearly the same. This was the source of the eiTor. 



One of the standing orders of iiarliamcnt was, that whenever a radway 

 had a cm've, with a radius of less than a mile, the commiffee must make a 

 sjiecial repoi't of such a ciu've, iqion the supposition that it was attended with 

 increased resistance or danger. The ])oi)nlar idea was, that when the wheels 

 got to the curve, the outer flange of tlie wheel mounted ujion the rail, by the 

 conical form of the tire, while the other fell from off the rail ; thus the one 

 wheel acquired a diameter virtually greater than the other; that, therefore, 

 one revolution of the outer wheel, having a virtually gre.iter diameter, would 

 carry it iivor a greater space than one revolution of the inner wheel ; ami 

 that the two things would accommodate each other so that the outer wheel 

 gets round a larger jiorfion of the rail, while the inner wheel, being virtually 

 smaller, gets over a smaller space, and that in this way the cone of the wheel 

 accomplished the thing. Never was there a more consummate lueehanieal 

 blunder. The fact was, the cone had nothing to do with the traversing of 

 the carriage round a curve ; and it was entirely the mechanical action of the 

 flange pressing on the rails. 



He had alluded to one or two circumstances connected with the practi- 

 cable and jirobable speed likely to be attained on railways, and the means by 

 which flmt speed might be attained. Since the great questions which had 

 been agitated respecting the effect which an increased width of rails would 

 have on railway transit, and the effect which very large drawing wheels, of 

 great diameter, v\onld have on certain railways, the question of veiy vastly 

 increased speed had acquired considerable interest. Very recently, two ex- 

 periments had been made, attended with most surprising results. One was 

 the case of the Monmouth express. A despatch was cariicd from Twyford 

 to London on the Great ^^'estern Railway, a distance of thirty ndles, in thirt y- 

 fi\e minutes. This distance was traversed very favouralily, and being subject 

 to less of those casual interruptions to which a longer trip would be liable 

 it was performed at the rate of six miles in seven minutes, or six sevenths of 

 a mile in one minute, or SGO-Tths of a mile (very nearly 51 3 miles) an hour. 

 He had experimented on speed very largely on most of the railways of the 

 country, and he had never jiersonally witnessed that speed. The evaporating 

 jiower of those engines was enormous. Another performance, which he had 

 asceiiained since he arrived in this neighbourhood, showed that great ,is the 

 one was just mentioned, they nuist not ascribe it to any jieculiar circumstance 

 attending the laige engines and wide gauge of the (Jreat Western liailway. 

 An express was desp.atched a short time since from Liverpool to Birming- 

 ham, and its speed was stated in the papers. One engine, with its tender, 

 went from Liverpool, or rather from the top of the tunnel at Edge Hill, to 

 l!irmingli.iiu, in two hours and thirty-five minutes. IJut he had inquired 

 into the circmnstances of that trip, and it ajqieared that the time the engine 

 was actually in motion, after deducting a variety of stoppages, was only one 

 hour and fifty mimites in traversing lunety-seven miles. The feat on the 

 (ireat A\'estern was performed on a dead level, while, on the Grand Junction, 

 the engine first encountered the Whistou incline, where the line rises 1 in 90 

 for a nide and a half ; and after passing Crewe, it encountered a plane of 

 three miles to the Madeley summit, rising 20 feet a mile, succeeded by 

 another plane, for three nnles more, rising 30 feet a mile ; yet, with all these 

 imiiedimcnfs, it performed the ninety-seven miles in one hour and fifty mi- 

 nutes, or 110 minutes; consequently the distance traversed in each minute 

 was 97 divided by 110, or -^)2y^, nearly 5,'i miles an hour — a speed which, he 

 confessed, if he had not evidence of it, he eoidd scarcely have believed to be 

 within the boumls of mechanical possibility. The engine which performed 

 this feat had driving wheels of 5.^ feet diameter; their circumference would 

 be \1\ feet. Taking the speed at 5.'^ miles an hour, it was within a very 

 minufi' fraction of 80 feet in a second of time. This was not the greatest 

 speed of the engine, but the average speed spread over 97 miles, and there 

 could be little doubt that it must have exceeded sixty miles an hour during 

 a considerable portion of the distance. Hr. Lardner concluded by saying, 

 " there was as yet nothing to satisfy us that a much greater speed was at- 

 fainablc by the adoption of the very large scale or gauge of r.ailway which 

 had been thought desirable by fliose who were interested in the Great Wes- 

 fi'ru Line." 



Lecturi! 1 1. 

 In this lecture the Doctor directed attention to a remarkable line of dis- 

 tinction which existed bclween inclin.'itions upon r.iilways of different kinds. 

 If, for instance, they had a gradient which would fall at the rate of one foot 

 in a thousand, the train would not roll down, because the gr.ivifafion would 

 be insnflicicut to overcome the mechanical resistance. But suppose the 

 acclivity were increased, so that the gravitation would just b.ilance the fric- 

 tion, that inclination would be what in mechanics was called the angle of 



