ABSTRACT
We have at various times throughout these chapters referred to statistical units, as for instance in the chapter on train loads, when we compared the average train load, firstly one year with another, and secondly with the actual and maximum results in daily working ; or again, when in Chapter XII on the marshalling yard we spoke of the units, (1) wagons dealt with per engine hour, and (2) yard wages per wagon entering the yard, by means of which we may compare the working results period by period or one yard with another.
