RAILWAY CONSTRUCTION. 51 



record speeds should only be attempted on the straight or 

 favourable portions of the line. There is, unfortunately, the 

 growing tendency to run faster and faster round the curved 

 portion of our lines, heedless of the close approach to the limit 

 of safety, and unless this excessive speed be controlled in time, 

 the result must be disaster on a very large scale. 



A sharp curve leading into or out of a terminal station or 

 main-line stopping-station does not so much affect the train 

 running as a sharp curve at an intermediate point between 

 stations where the train may be expected to run at its maximum 

 speed. Wherever it is possible it is very desirable to avoid 

 sharp curves on inclines, because there are times when descend- 

 ing trains may acquire a considerable velocity, and wheels 

 tightly gripped by the brakes have not the same facility for 

 following the curves as when they are running free. 



In rugged and mountainous districts sharp curves are almost 

 unavoidable, except by introducing a series of tunnels ; but in 

 these districts both the gradients and curves are alike excep- 

 tional, the speed is necessarily slow, and special precautions are 

 taken for the ascending and descending trains. 



When setting out reverse curves on a main line a piece of 

 straight line should always be laid in between the termination of 

 the one curve and the beginning of the other, to allow of a proper 

 adjustment of the rails to suit the super-elevation adopted on 

 each of the adjoining curves. In station yards and sidings this 

 is not so absolutely necessary, the sorting of the carriages and 

 waggons and the marshalling of the trains being carried on at a 

 low speed, which does not necessitate any super-elevation of the 

 rails on the curves. The speed of the train regulates the amount 

 of super-elevation to be given on any particular curve, and to 

 ensure smooth and safe running this amount must be maintained 

 uniform all round the curve. On curves of small radius, guard, 

 or check, rails are frequently placed alongside the inner rail, 

 as in Figs. 30 to 33, to check the tendency of the engine to 

 leave the rails and run in a straight line. For the bull-head 

 road a special chair is used, which holds both the running- 

 rail and the check-rail, as shown on the sketch, the rails being 

 kept the proper distance apart by the web portion in the centre, 

 which forms part of the casting. For the flange railroad, check- 

 rails are sometimes made of strong angle irons placed against 

 the flange of the running-rail, and bolted to the transverse 



