” 75 | -- | 43 | 94 | 164 | -- | 95 | 163 | 240 ” 70 | -- | 39 | 86 | 152 | -- | 88 | 153 | 226 ” 60 | -- | 28 | 70 | 128 | -- | 74 | 131 | 196 ” 50 | -- | -- | 53 | 101 | -- | -- | 107 | 163 ” 40 | -- | -- | -- | 73 | -- | -- | -- | 127 ” 25 | -- | -- | -- | 27 | -- | -- | -- | 67 -----------------------+-----+-----+------+------+-----+-----+------+------ NOTE.--The column loads in tons are exclusive of the weight of engine and tender. From the above memoranda it will be seen how greatly the gradients 45 affect the loads. For an important main trunk line, with a heavy and frequent train-service of passengers and goods, the introduction of steep gradients would not only reduce the speed of the train-working, but would probably involve the necessity of assistant engines over those parts of the line; and it may be prudent, where possible, to incur heavier earthworks, or considerable detours, or tunnels, to obtain more favourable gradients. For such a line the additional cost, and the extra distance caused by a detour of a mile or more, will be of far less importance than the interruption in the train service arising from a serious reduction in speed or taking on assistant engines. On many railways abroad there are very interesting examples of long detours of several miles, carefully studied out to obtain greater length and easier gradients, resulting in the construction of lines over which the traffic can be worked without necessitating auxiliary engine-power. On the other hand, there are situations where steep gradients cannot be avoided, where certain altitudes must be reached, and where there is no alternative but to face the inevitable. On secondary lines, and short branch lines, where the traffic is not expected to be heavy, and where speed is not so important, it may be policy to economize outlay and introduce steeper gradients than on the main line. Half a mile of a rather steep gradient is not felt so much when it is situate midway between two stations, because the attained speed of the train assists the engine over the short distance to the summit; but when it occurs as a rising gradient out of a station, it forms a great check to the working, particularly in bad or wet weather, when there is the risk of the engine slipping, and the entire train sliding back into the station.