Page:Science vol. 5.djvu/115

 Jasvary 30, 1365.1

��eogineers of otber couotries can learn muob from their study.

He first desoribes and illustrates the method of constructing tbe portion of the London underground rnilway between Aldgate station and the Maa.sion house, by the way of the Tower. The difficulties encountered from gas and water pipes, sewers, and foundations of buildings, and the necessity of providing for the coDtiouance of street-traffic, called for in- genioDs contrivances, by means of which the construction was successfully carried forward. Beton or concrete was used for the invert, betOQ or brick for the side-walls, and brick arches covered tbe top. All varied in thickness to suit the circumstances of the case, and the superincumbent load.

Next follows an account of the building of a tunnel in London for the Midland railway, with illustrations of the timbering employed in the work, and the tunnel cross-section toaad best adapted to resist the pressure of the London clay. A brief description of a oonteinplated subwuy under the Thames at Woolwich is then given.

The tunnel under the Mersey, between Birk- enhead and Liverpool, a little less than a mile long, cammunicalioD between the ends of which was opened early in 1684 ; and the Severn tun- Del, not far from Bristol, to be four miles and a half in length, and now well advanced. — oc- cupy in description about one-half of tbis report. The drainage -tunnel below the main tunnel under the Mersey ; the arrangcinents for pump- ing and ventilation ; the introduction of Col. Bnumoat's machine, which had previously bored five thonsand linear yards through chalk in the proposed tunnel under the English Chan- nel, and here bores a hole aeveo feet in diam- eter through the sandstone rock, — are well described. The Severn tunnel is prosecuted with drills driven by compressed air. Prog- ress has been hiudered from time to time by the influx of water, even to the extent of com- pletely flooding the works. The pumps re- quired are consequently very powerful, having a capacity of eighty-two thousand six hundred eobic metres in twenty-four hours.

With the exception of two pages devoted to an intercepting or tnmk sewer at Biighton, the eiodng pages are devoted to an account of the examinations and investigations already made in rv^ard to a tunnel under the English Chan- nel, between Dover and Calais, the present ■tote of the project, and the possibilities of the sdieme.

The book is handsomely printed, and the QilMttations are very clear and explicit.

��NOTES AND NEWS.

Is a lecture at Johns Hopkins oa the pltce of the science of hygiene In a liberal education, Dr. Billings states the objecllons to the entabliBbment of such a caane, as follows: first, that there Is no existing demand on the part of students for It ; second, that the subject is not yet on a aclentlllc basis; third, that Che present courses of instruction given in the chemical, physical, and biological de- parLineuts of the university, include all that a well- t'ducated man need know of tills subject, unless be proposes to make it a specialty ; fourth, that the students have no time for any studies additional to the course already supplied. To the first objection Dr. Billings replied, that the same might be said as to oilier branches of the curriculum, — that the ma- jority of Btudenls do not know what they ought to study, — and that the question is, whether the time baa not come to create the demand, and for the unl- versilj' to lead the way in the matter. The second objection is only partly true. The general rule holds good In man, as it does in the laboratory, that like causes, under like circumstances, will produce like effects. When it has been shown in a number of well-marked cases that polluted water has been the means of spreading Cygbo id-fever, that overcrowding and foul air precede epidemic typhus, that scarlet- fever or diphtheria has been conveyed to a village by Infected clothing from a distance, we have enough information to enable us to advise in similar caiea, although we also know that men have druiilc sewage with iinpujiity. and that unprotected children have slept in the same i>ed with a scarlet-fever case and have not taken the disease.

— The foundations under the stone piers support- ing the iron bridge, twency-Sve feet above low-water level, by which the Wabash, St. Louis, and Pacific railway crosses the Kankakee Biver, have lately been giving trouble. The bed-rock of shale is hard and soft in places in the short space of a few feet. The three piers were built when the water was high, and were placed on platforms of foiu* thicknesses of pine tim- ber twelve inches square. Before these platforma were located, some of the loose maturlsl was removed ; but it would appear that the foundation was dug deepest in the centre, and the rapid current of high water washed under and disturbed the piers. In order to till the space, give a firm bearing over all the bottom, make the piers tlioroughly durable, and at the same time not interrupt or Interfere with the traf- fic over the bridge, the application of wooden wedges was suggested and carried out by P. E. Falcon of Chicago, By a strong jet of water and other appli- ances, the sediment and loose material were cleared away by divers from under two timbers at a time, and the bed-rock was cut away to a level. Oak timl>era were fitted to the cavity; and a double row of broad oak wedges, to Insure a complete bearing from Uie middle of the pier to the outside edge, was driven between the oak timbers and the pine platform tiy means of a steel bar weighing eight hundred pounds, suspended from the bridge by wires, and tdyiWAd, vi

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