For each train that goes out, then, five men must be in readiness. The caller looks through his book, sees whose turn it is, goes to the dwellings of the men to be called, and notifies them of the hour they must be on duty. If any of them are ill or absent, he goes on and calls some one else. The passenger-trainmen, having regular runs, know, of course, the hours they must report for duty and do not need to be called. They are also paid a monthly salary, whereas the earnings of the freight crews vary with the amount of business done by the road. For each man must wait his turn. When business is slack and few freight-trains are needed, that turn is often a long time coming; but when business is heavy it frequently happens that the road finds itself short of men and the same crew which has just brought in one train is compelled to take out another, and is sometimes on duty for sixteen, twenty-four, and even thirty-six hours at a stretch. It is then that nerves give way, that memories fail, that eyes which should be alert grow dim and weary,--orders are forgotten, signals are unseen, and a bad accident follows. Freight-men are paid by the trip, and not infrequently, in busy seasons, they make double time--that is, get in two days' work in every twenty-four hours. As has been said, the engineers and conductors register at once at the dispatchers' office. Then the engineer goes on to the lower yards to look over his engine and see that it is in good shape, while the conductor waits for his orders. These are given to him in duplicate, one copy for himself and one for the engineer. He reads his copy aloud to the dispatcher, compares his watch with the big official clock, and then goes down to his train. As soon as the engine is coupled on, he gives the engineer his copy of the orders, which the engineer must read aloud to him. Then they compare watches, and the conductor goes off to show the orders to the rear brakeman, while the engineer shows his copy to the fireman and front brakeman. Thus every member of the crew knows under what orders the train is to proceed and its movement is not dependent upon the memory of one man alone. The dispatcher has also kept a copy of the orders, which he files away. At the time appointed in the orders, the conductor gives the word and the train starts on its journey.