for a double line. The earth-waggons are hauled along the line from the excavation, and brought to a stand at the point A. If a locomotive has drawn the waggons, it is then detached, moved forward, and shunted back into the siding BC. A horse accustomed to tipping then takes one full waggon at a time over one or other of the two turn-outs, DEF or DGH, to the tip head, sufficient impetus being given to the waggon to run the front wheels off the ends of rails on to cross-sleepers laid close, with a steep rise, and backed up with 69 earth. This suddenly checks the frame of the waggon, and the body containing the excavated material revolves on its trunnion, tilts up, and shoots out the material well forward, so that the man in charge of the tip head, who also knocks up the “tail-board catch,” is able to level off the filling without assistance. The empty waggon is then hauled back, and turned into the siding BC, and another full waggon taken forward and tipped, until all the waggons of the rake are emptied. Ten waggons generally form a rake when the work is pushed forward vigorously, each waggon holding about three tons. The tip head horse pulls the waggon by a trace-chain having a spring catch at the end, by which the driver releases the horse at the right moment. It is very important that this spring catch should be kept in good order, because occasionally too much impetus is given to a waggon, which, running over the tip head down the slope, would drag the horse with it if the spring catch did not act properly. Good firm foothold must be provided for the tipping horse. The tip head should never be carried across culverts or bridges until they have been well backed up, and protected by a thick covering of earth or clay, wheeled in with barrows to an equal height on each side of the masonry, so as to prevent undue side pressure. Fig. 59 gives a sketch of one form of end-tipping waggon. In some cases the wheels are made of cast-iron, but as these are readily broken during the rough handling to which earth waggons are exposed, it is questionable whether the light wrought-iron wheels, with light steel tyres, used on some works, are not more economical in the long run. The framework and body are made of strong undressed timber, well bound and bolted together. The tail-board catch keeps the body of the waggon in its proper horizontal position while loading or running, but when released leaves the body free to tilt up, and to revolve on the front trunnion by means of the circular clip A. The same principle is also applied to side-tipping waggons which are used for the widening of embankments, or formation of platforms and loading-banks.