Red lanterns are left in the street where the policemen stood during the daytime, while they retire to some doorway where, it is said, they sleep as soundly as their brethren in the States. Every hour they blow a whistle like those used by by those on the next posts. Thus they know all is well. In small towns they call out the time of night, ending up with tiempo serono (all serene), from which the Mexican youth, with some mischievous Yankeeism, have named them Seronos.
