It has been noticed that boiler explosions are especially frequent in the morning. Take, for example, an engine which works during the day with steam at six atmospheres. The workmen leave the factory at seven o'clock P.M., and about six o'clock the fireman reduces his fires and leaves the boiler with the gauge at four atmospheres. On returning the next morning at half-past five, he generally finds the gauge at 1.5 or two atmospheres, with a fine water level. He profits by the reserved heat, which represents a certain expenditure of fuel; as an economist he utilizes it, and drives his fires, to be ready for the return of the workmen, without suspecting the dangers concealed in the water which has been boiling all night. He does not feed his boilers, because they are at a good level. In other words, he prepares, unconsciously, the conditions which are most favorable to superheating, and a consequent sudden and terrible explosion, which will be attributed to some mysterious and unknown cause. Southern Sketches. XIX. FROM HAVANA TO MATANZAS--THE VALLEY OF THE YUMURI. There are two railways leading from Havana to Matanzas, one called the via Baya (Bay line) runs along the sea coast through a mountainous and romantic country. This is much shorter than the other route, which passes through the interior, affording the traveller an excellent opportunity of observing the rural tropical scenes of the island. I decided to go the latter way by the train, which was to start from the depot near the Campo de Marte at 2.40 P.M. The fare from Havana to Matanzas either way, second-class, is $7.10 in Cuban currency. This class is well patronized by respectable travellers. Negroes, Chinese and the poorest Cubans take the third. The carriage in which I rode was built and furnished somewhat like those in the United States, except that the seats had no cushions, and the windows no glass. The train started at the appointed time, and we soon found ourselves rushing through narrow streets, past many colored buildings.