184.8.] 



THE CIVIL ENGINEER AND ARCHITECrS JOURNAL. 



2T 



if there had been no leakage, the train-piston would have advanced 

 that lengtli further during the minute. 



This is a brief and imperfect sketch of Mr. TurnbuU's system. 

 We must observe, liowever, that the results will agree only ap- 

 proximately with actual practice. The fundamental hypothesis of 

 uniform velocity of the train, is not unobjectionable : it is true that 

 in calculating the motion of locomotive engines, the hypothesis 

 will lead to results of specific value ; but, on atmosplieric railways, 

 the distances performed with accelerated or retarded speed must 

 bear so large a proportion to those performed with uniform speed, 

 that the latter can hardly be considered the normal condition. 

 There are otlier reasons for concluding that calculations of the 

 motion of trains on atmospheric railways cannot be exact. How- 

 ever, the partial application of sound theoretical principles to 

 practical subjects, of which a perfect theory is unattainable, is a 

 most important advantage. The skilful research exhibited in Mr. 

 Turnbull's treatise, is the more welcome for being applied to a 

 subject which has, in a pre-eminent degree, suffered the martyrdom 

 of parliamentary and newspaper philosophy. 



A Guide to the Proper Reyulat'wit of Buildings in Towns as a 

 means of Promoting and Securing the Health, Comfort, and Safety 

 of the Inhabitants. By AVm. Hosking, Architect and C.E. Lon- 

 don : Murray. 1848. 



This work of Mr. Hosking evidently contains so much practical 

 and useful matter that we do not like to dismiss it with a passing- 

 notice, but we intend to devote a little time to its consideration. 

 Meanwhile, whatever opinion we may entertain with regard to 

 some of its recommendations, we have seen quite enough of it to 

 feel justified in i-ecommending it to our professional readers. 



EaHhwork Tables. By C. K. Sibley and W. Ruthebfobd. 



The authors have published an appendix to these very useful 

 tables, showing how the tables may be applied to side-lying gi-ound, 

 for which they give the following rule : — " Ascertain the ratio of 

 the area of cross sections of the side-lying ground to the areas of 

 similar cross sections, tliat is with same height on centre line, of 

 level-lying ground, and multiply by that ratio the complete quan- 

 tity furnished by the tables." 



The Antiquarian and Genwdogist's Companion. By AVilliam 

 Downing Beuce, Esq., F.R.S.L. & E. 



This is a novelty for the antiquarian student, which will be very 

 favourably received at the present season, as it contains many 

 curious memoranda and an archaeological calendar for the year. 

 The work is small — which may, perhaps, be an additional recom- 

 mendation. 



LECTURES ON GEOLOGY 



By Professor Ansted. Delivered at King's College, London. 



On the Application of Geology to Engineering and Architecture, and the 

 Supply of Water to Towns and Cities. 



Professor Ansted commenced his fifth lecture, by considering the ques- 

 tion of drainage, more particularly with refcience to general engineering, 

 which depended, in many cases, very distinctly on the geological structure 

 of the rocks. And it did so naturally, as, for instance, in an ordinary road, 

 properly made, where the drainage would ultimately have reference to the 

 structure of the material and to the rocks in the neighbourhood. With re- 

 gard to geological structure, it might happen that the beds which came close 

 to the surface would have a strong inclination ; and, in that case, where the 

 beds were permeable, the road would be drained naturally, and, where one 

 part lay on an impermeable bed, and the other on a material which suffered 

 the water to percolate through it, an attention to geological structure would 

 enable them to carry off all the water very satisfactorily. This would illus- 

 trate the applicability of geological knowledge, even to common road mak- 

 ing ; but that knowledge was still more directly available in the case of rail- 

 roads, v\hich, running through a long extent of country, involved the neces- 

 sity of frequent and deep cuttings, in the execution of which drainage, as 

 connected with structure and geological considerations, must always come 

 in. Suppose, then, they were to take a transverse section of a railway cut- 

 ting, similar to one of the diagrams exhibited — if the beds were horizontal, 

 the two sides would he situated in a similar manner with regard to accidents 

 arising from unequal pressure ; but if that were not the case, and the bank 



was composed of mud, clay, sand, or any slippery earth, in beds inclined to 

 the horizon, some parts of the superincumbent mass would be more apt to 

 slip down than others. Some strata would carry water, and others would 

 allow it to drain through ; and if the road did not go directly on the strike, 

 in which case there was no inclination as far as the purposes of the road 

 were concerned, there would be a greater tendency to " slip" on the one 

 side than on the other. Supposing the uppermost beds were composed of 

 some heavy material resting upon a bed of sand, the rain, in draining through 

 the sand, would wash it away gradually, and, a portion of the support being 

 removed, the upper mass would naturally have a tendency to slide down 

 upon the lower part. If once it began to slide, no matter how slowly— if 

 the moveruent were only an inch per day, or an inch per month— any pre- 

 ventive measures were too late, and there would be a slip sooner or later, 

 and especially in heavy rains, or rains combined with frost. But before the 

 superincumbent mass were set in motion, if by any means the water could be 

 prevented from passing through the sand, it might be prevented. That was 

 best done by cutting a drain on the other side, by which all the water which 

 came on the surface might be carried off before it reached the sand. There 

 would then be sufficient cohesion to prevent the upper part from being set in 

 motion. 



A knowledge of geological structure, in making these cuttings, was ex- 

 ceedingly useful, not only in preventing slips, but in reducing the cost of 

 work. For instance, when the dip was in a certain direction, a shp was 

 manifestly impossible, and in that case the slope of the bank might be very 

 much steeper, and the expense of its removal saved. Cn the continent, it 

 was not unusual in cuttings to make the banks in a succession of terraces ; 

 but, in this country, that plan, though exceedingly useful, was scarcely ever 

 adopted. It was, however, being partially iried at New Cross, a place where 

 much mischief had been done by slips, and he believed with a prospect of 

 success. That was, however, a plan which could not be carried out without 

 a reference to geological science. 



On the subject of embankments the same principles of drainage were ap- 

 plicable, though another elemeut of construction was brought into action. 

 If a large mass of material were heaped in a particular way, it might be per- 

 fectly safe, and answer the purpose intended very well ; while if it were 

 placed in a different way, mischief would arise. The structure of embank- 

 ments ought also to be regulated by the nature of the rocks on which they 

 rested, as well as those of which they were formed ; and although, as yet, 

 few accidents had arisen, engineers might find it worth while to pay atten- 

 tion to this subject. Again, if an embankment was placed on a hill side, 

 there ought to be particular adaptation to the way in which the beds lay. 

 If a heavy pressure were put upon beds so situated, which had already a 

 tendency to slip, that tendency would be increased, and, unless attention 

 were paid to the drainage, serious accidents would inevitably occur. The 

 kind of draining required was much of the character of that necessary in 

 ordinary roads — namely, by cutting off springs which had a tendency to run 

 between bands of impermeable rock. 



The subject of canals, and the way in which they were affected, introduced 

 another element. Id making canals, the engineer would constantly have to 

 cut across springs, and through some strata which allowed water to percolate, 

 and through others which actually produced water. In going across a dis- 

 trict where there was much leakage, it was necessary to have a perfect 

 knowledge of the nature of those rocks which yielded water and abounded 

 in springs ; and of those strata and substances which were impermeable. On 

 such circumstances depended many great practical difficulties in the con- 

 struction of canals. It was a remarkable fact, that Mr. William Smith, who 

 flourished about a century ago, and who was called the father of Enghsh 

 geology, was himself a mining engineer, and first observed the geological 

 structure of the country, as it afTected the formation of canals. His life, 

 lately published by Professor Phillips, his (the lecturer's) predecessor at 

 King's College, would be found very useful and interesting, as it regarded 

 the practical application of so much of geological science as was known at 

 that day. In the Hfe of Smith would be found some account of the con- 

 struction of canals in his day, then as important as raUways were now. They 

 would see how he brought his knowledge to bear upon the problems at issue, 

 and in that way they might themselves learn how to apply a great deal of 

 that knowledge of geology which they might possess. 



Supply of Water. — The Professor next treated of the supply of water as 

 an engineering subject, apart from the supply obtained from land-springs, or 

 small Artesian wells, considered hitherto on a comparatively small scale, and 

 rather with relation to agricultural purposes than engineering. The subject 

 of drainage and water supply was, perhaps, connected as much with archi- 

 tecture as engineering ; but, when he had discussed its relations to the one, 

 it would scarcely be necessary to touch upon the other. 



With respect to the supply of water, the Professor thought he could not 

 do better than give them a short outline of what had been done lately with 

 regard to the large and most important town of Liverpool, which had been 

 noted, for some time, as a place which was badly supplied with water, and 

 had been more remarkable than any other town in England, for the pre- 

 valence of fevers, the more than average illness of its inhabitants, and the 

 short duration of hfe in the major part of it. The members of the corpora, 

 tion appeared very anxious to do all in their power to remedy that which 

 was certainly one source of those evils — namely, the deficiency in the supply 

 of water. Accordingly, they resolved to obtain an Act of Parliament, em- 

 powering them to adopt some measure, which should give the town a larger 

 quantity of that important element. The town was situated on the new 



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