With cast iron pipe this cannot be done, and no length of piping over 40 ft.
Later, the serendipitous drippings were augmented by additional piping, carrying excess water to spray even more surface of the rock walls.
In the United States the danger of the stoves that used to be employed for heating the interiors of the cars has been realized, and now the most common method is by steam taken from the locomotive boiler and circulated through the train in a line of piping, rendered continuous between the cars by flexible coupling-hose.
The piping takes a winding or zigzag course, and by the time the outlet is reached, the water it contains has reached a high temperature.
Of late years a considerable amount of seamless tubing has been made, much in the same way as lead piping, by forcing the mixed rubber through a die, and curing as above.