engine have sharp or worn flanges there is the possibility that the wheel, pressing against the high rail, may mount the rail, and throw the train off the line. A more secure method is to place the guard outside the high rail, as in Figs. 34 to 38. This can be done by securing a strong continuous longitudinal timber to the cross-sleepers--or to the cross-girders in the case of a girder bridge--with its outer or striking edge protected with a fairly heavy angle iron. The top of this outside guard above the rail level may be three inches or more, according to the height of any hanging spring, or portion of brake apparatus belonging to the rolling-stock. The distance between the striking-face of the guard and the inside of head of rail should be about 5 inches, or such width that before the flange of the wheel can mount on the top of the rail, the face of the wheel-tyre will be brought into contact with the striking-face of the outside guard, and thus effectually prevent the wheel leaving the rail. The sketches show some of the types applicable to the chair road, and to the flange railroad. In Figs. 34, 35, and 37, the outside brackets are of heavy angle iron cut off in lengths to correspond to the width of the sleeper. In Fig. 36 the cast-iron chair is lengthened, and has an end bracket to support the guard timber. In Fig. 37 a hard wood bolster is fastened on the top of each sleeper, and on this is placed the continuous guard timber. This method of increased security is frequently adopted on girder bridges and long iron viaducts which are on the straight, and in such cases it is usual to place the guards outside each of the rails forming the track. The introduction of bogie engines and bogie carriages has conduced largely to the safe working of the train-service over the curved portions of many of our home railways, as well as to the economy in the wear and tear of permanent way and rolling-stock. The action of long rigid wheel-base vehicles passing round sharp curves is 54 detrimental to all the parts brought into contact. Not only is there the constant tendency to mount the rails, and spread the gauge, but the tiny shreds of steel scattered all along close to the rail--particles ground off the rails, or off the wheel-tyres, or both--testify to useless wear, unnecessary friction, and great waste of motive-power.