When steam at atmospheric pressure is condensed into water at a temperature of 212° F., each pound of steam gives up 966 B. T. U. of heat; but if steam of 100 lbs. gauge pressure (115 lbs. absolute) is condensed into water at 212° F., each pound of steam must give up 1004 B. T. U., which is only 38 heat units more than are contained in steam of atmospheric pressure. It is evident from this that for heating purposes there is no advantage in using steam of a high pressure. One pound of exhaust steam, only a pound or two over atmospheric pressure, is almost as valuable an agent for heating purposes, as live steam at 100 lbs. pressure direct from the boiler,