FIRE-PROOF BUILDING CONSTRUCTION. 619 



on a single block of the same construction. The cost of these founda- 

 tions was less than the estimate made for the same in first-class brick 

 or stone mason-work. 



It has also been used for lining a reservoir of ninety-six thousand 

 gallons capacity, which was blasted into a ledge. 



Another great advantage realized in re-enforcing beton with iron, 

 is that the iron overcomes its tendency to check in hardening, within 

 useful limits, however large the surface may be, if the distribution of 

 the iron through the work is made with ordinary good judgment. This 

 is demonstrated in the instance of entire freedom from shrinkage 

 checks in the single section of beton-flooring laid in the drawing-room 

 of the house. Its dimensions are eighteen by thirty-six feet, three and 

 a half inches thick, and after a period of eight years, during six of 

 which it has, in winter, been more or less subjected to unequal strains 

 from the expansion and contraction, caused by changing temperatures, 

 while employed as a transmitting medium of heat for warming the 

 room, there is no trace of a check throughout its whole extent. 



The method of heating the house is shown in Fig. 2, where the 

 section exhibits the arrangement of hot-room and heating-flues in the 

 walls and floors. 



In the center of the cellar is a heating-chamber, measuring eleven 

 by sixteen feet, and eight feet in height. Within this chamber is 

 placed an ordinary cast-iron heater, of a capacity for burning about 

 three hundred and fifty pounds of coal per day. Openings were made, 

 about twelve inches apart, all around the top of the surrounding walls 

 of the chamber, leading outwardly to the spaces between the first 

 floors and the cellar-ceilings, and also up through the flues within the 

 interior walls, which communicate with the spaces between the second- 

 story floors and ceilings beneath them. Vertical iron pipes, of suit- 

 able size, are located so as to connect the open spaces between the 

 cellar-ceilings and first floor with a large, closed trunk, or passage- 

 way, which extends nearly all around the inside of the main wall 

 foundation, under the cellar-floor, and finally terminates in a large 

 flue, which leads directly under and into the heating-chamber. 



This comprises about the whole system of arrangements in the con- 

 struction for warming the house with heat radiated from the floors 

 and interior walls. 



Its mode of operation simply consists in the body of warmed air 

 passing from the heating-chamber upward, through the walls and un- 

 der the floors, and in its passage giving up its surplus heat to the sur- 

 faces of these flues. As the air becomes reduced in temperature, it 

 naturally descends through the pipe and trunk passage-ways provided 

 for its return to the heating-chamber, where it is again recharged 

 with heat. It will readily be seen that, by this method, a continu- 

 ous circulation will be maintained with the same quantity of air ; and 

 furthermore, that the velocity of the current will vary with the dif- 



