UAIT-KOADS. 503 



to tlie general confirmation which our natine engineers give it by the 

 published results of their own enquiries), that a railroad cannot be 

 advantageously constructed, that is, without great sacrifice of power, 

 with gradients more than about two feet (Dr. Lardner says, seventeen) 

 in a mile, and that when the slope attains the degree of one in fifty feet 

 the roadis then traversed at such disadvantage as to render it impos- 

 sible to make it a line of transport for heavy goods without additional 

 locomotive and stationary engines. The greatest possible number 

 of passengers (giving the low average of eleven stone to a passenger) 

 to be transported on a slope of one to fifty would be fifty-lhree, and 

 for all practical purposes we may state forty as the average number 

 that such a slope would allow. The calculations are made with re- 

 ference to the best engines now at work on the Liverpool and Man- 

 chester railroad. 



Slopes, when necessary, if more than twenty feet in a mile, should 

 be short ; for they must be passed either by dividing the train or by 

 assistant locomotives. From these facts it seems probable that rail- 

 ways cannot be led over highlands that rise considerably and sud- 

 denly above the levels on either side. In explanation of this we again 

 cite the section which is before us of the Leeds and Manchester rail- 

 road. It there appears that it commences at anelevation of 163 ft. 7 in. 

 above the sea (measured at the Old Dock, Liverpool) ; it rises in ten 

 miles 306^ feet, i. e. rather more than thirtt/ feet per mile, and on 

 the eastern side, in the three miles nearest to the summit-level at 

 Todmorden tunnel, the rise is rather more than thirty-six feet per 

 mile. Hence the sacrifice of mechanical power on both inclines 

 must be very great,— perhaps not too great to be justified by the 

 necessarily extensive comnmnication between Leeds, the great 

 woollen, and Manchester, the great cotton staple of England, and 

 by the increased intercourse that may be expected between the ports 

 of Liverpool and Hull, which ai-e the teinnini between the proposed 

 line ; — but we know other railroads, on which slopes scarcely less 

 disadvantageous are to be found in countries, where no such extraor- 

 dinary commercial advantages exist ; and we feel it to be our duty to 

 warn our readers against risking capital in undertakings, which, on 

 the calculation of scientific men, cannot justify the expectation of 

 even moderate returns. 



We next consider the curves on railroads; and with respect to 

 them we may first observe generally, that they must be large in pro- 

 portion to the velocity with which carriages run on them. Curves are 

 at ail times inconvenient to a certain degree, because the object in 

 a railroad is to make the distance as short as possible between the 

 termini; but they are occasionally necessary to avoid the sudden 

 elevations of the surface, and if properly managed they may be often 

 contrived so as to counterbalance the inconvenience of lengthening 

 the distance. The least admissible radius for a curve is a mile (and, 

 if we admit this, the curve near Weedon barracks, in the Birming- 

 ham and London Railway, is somewhat too confined), and where 

 there is an increaHed velocity in transport it must he considerably 

 greater, if the safety of passengers to be transported along the line 

 is to be properly considered. To this point, then, as well as others 



