The increased loading space required in the sheds is obtained by multiplying the number and the length of lines and platforms; sometimes also there are short sidings, cut into the platforms at right angles to the lines, in which wagons are placed by the aid of wagon turn-tables, and sometimes the wagons are dealt with on two floors, being raised or lowered bodily from the ground level by lifts.
In dams of moderate height above ground and considerable depth below ground there is, moreover, no reason why advantage should not be taken of the earth resistance due either to the downstream face of the trench against which the foundations are built, or to the materials excavated and properly embanked against that face above the ground level or to both.
The maximum pressure is not uniform from the ground level to the roof but is greatest at the centre; it is diminished near the ground level by the frictional resistance of the ground, and at the eaves by the eddies formed by the air escaping over the roof.
Here the jib, superstructure and post are all united in one piece, which revolves in a foundation well, being supported at the bottom by a toe-step and near the ground level by horizontal FIG.
Intermediate stations, like terminal ones, should be convenient in situation and easy of approach, and, especially if they are important, should be on the ground level rather than on an embankment or in a cutting.