738 KANSAS CITY REVIEW OF SCIENCE. 
system is being gradually extended ; while for large blocks, such as apartment 
houses, hotels, manufacturing establishments, school-houses, and other large struc- 
tures, the system is so greatly in demand as to have given rise to new and ex- 
tensive industries devoted to the manufacture and installment of the necessary 
apparatus. 
Steam heating is characterized by the fact that the heat is generated in the 
furnace of a boiler either within or without the walls of the building to be heated, 
the heat of combustion being transferred to water, which, being vaporized, con- 
stitutes the medium by which the heat is conveyed in comparatively small pipes 
to the points where it is utilized for heating purposes. Two distinct methods of 
utilizing this heat are practiced. In one the steam pipes are carried, by the 
most convenient course, directly into the room or space to be heated, where, by 
convolutions of the pipes, or what are known as radiators, an extended heating 
surface is furnished to the room. These coils, or radiators, give off heat both 
by radiation and by contact with the air, which is kept slowly circulating, as in 
the case of a close stove ; and it is evident that only a feeble, or at least uncer- 
tain, ventilation is possible, except through special arrangements made for intro- 
ducing fresh air. These heated coil's are, in effect, identical with close stoves, the 
only difference being that the surfaces of the coils can never be heated to a de- 
gree higher than that of the steam, — practically, never higher than 310° nor 
lower than 215° or 220° Fahr., while the surface of the close stove may, under 
some circumstances, approach 950°. Active and sufficient ventilation may be 
attained with these coils, however, if they are placed in such a way that cool 
air, introduced through openings, — as, for example, under windows — will mingle 
directly with the heated air rising from the radiators, and then be deflected up- 
ward to be mixed with the general circulation, and discharged through ventilat- 
ing flues. Of course, such active ventilation can only be attained at the expense 
of additional heat. 
The other method, called by a strange misconception "indirect radiation," 
consists in conveying the steam from the boiler to small chambers constructed 
for the purpose, in the basement, directly beneath the rooms to be warmed. 
Here the steam pipe is extended into a coil, or an equivalent arrangement, by 
which a large amount of steam-heated surface is exposed. Flues for heated air 
lead from the roof of the chamber to the various rooms to be heated; an inlet 
duct for fresh air enters the bottom of the chamber, and the coils, or "radiators " 
are so arranged that the air in rising comes in contact with the heated surfaces, 
and passes to the apartments to be warmed with the temperature increased to 
70° or 100° Fahr. Low temperature currents only are generated; and as the 
proper action of the apparatus can be kept up only by a continuity of flow into 
and out of the space to be heated, the two effects of heating and ventilation are 
most effectively conbined. 
A comparison of these various methods must include the cost of the appa- 
ratus, the cost of attendance, the cost of fuel, and the incidental advantages and 
disadvantages belonging to each. The open fire-place possesses the advantage 
