for a mile ahead of him he keeps on. He, too, forms a habit which has to be reckoned with some day.
Again, all trainmen understand that an express train has no business to run past a station while accommodation trains are discharging passengers. It is by no means an uncommon occurrence, however, to see an express train disregard these positive instructions, on the strength of hand motions given by trainmen on the accommodation train to the effect that they are about to start, and that the way is safe and clear for the flyer. Yet in this manner accidents happen, and passengers from the accommodation are always likely to be caught in a trap between the trains.
But the dangerous and widespread effects of the permissive principle applied to important rules will be appreciated to the full when we study the interpretation which railroad men in general are in the habit of applying to the word caution.
On all railroads there are certain fixed signals for the guidance and information of employees. When caution is called for, the light is usually green and the semaphore horizontal. Now, as the writer looks at it, when any signal indicates caution, it is not to be looked upon as a permissive or conditional signal to be interpreted at will by different enginemen. According to the rules and to common sense when a train, at the time a cautionary signal is
