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.
Compared with heating by hot water, steam-heating requires less piping, which, further, may be of much smaller diameter to attain a similar result, because of the higher temperature of the heat yielding surface.