boiler are attached. Everything that is not satisfactory is noted for rectification when the engine returns. A second trial may occasionally be necessary, especially in the case of an engine of a new class, and finally, when everything is satisfactory, the engine is sent to the paint shop to be painted.
An express engine is not at once set to work on fast trains, but for about three weeks it is employed on local stopping passenger trains at the shed where the works are situated. This gives the engine an opportunity of “finding its bearings,” and any defects which may show themselves are rectified. Afterwards the engine is tried for a week or two on fast trains, and is then ready for regular service and is sent away to its allotted station. An engine which has come out of the works after repairs undergoes exactly the same routine.
Special Tests in Service. These are usually “road tests,” that is, they are made in service on the line when the engine is working its usual trains. Generally such tests consist of a long daily series, extending over a period of several weeks, and they are generally undertaken, when it is desired to estimate the coal and oil consumption of a new or altered class of engine in order to compare the results with those given by an engine of an existing class, which has hitherto been working the same trains.
For this purpose records are kept of the weight
