Occasionally the joints thus formed are " supported " on a sleeper, as was the practice in the early days of railway construction, but they are generally " suspended " between two sleepers, which are set rather more closely together than at other points in the rail.
At one end of each rail the flange spread out to form a foot which rested on a cross sleeper, being secured to the latter by a spike passing through a central hole, and above this foot the rail was so shaped as to form a socket into which was fitted the end of the next rail.
Each length was thus fastened to a sleeper at one end, while at the other it was socketed into the end of its fellow.
In that most largely used, known as " creosoting," dead oil of tar, to the amount of some 3 gallons per sleeper, is forced into the wood under pressure, or is sucked in by vacuum, both the timber and the oil being heated.
Sometimes a strip of felt is interposed between the chair and the sleeper, and sometimes a serrated surface is prepared on the sleeper for the chair which is forced into its seat by hydraulic pressure.