616 THE POPULAR SCIENCE MONTHLY. 



both for the floors and roofs, and by the same method as the experi- 

 mental beam above described. The iron beams varied in width and 

 weight per yard in accordance with their length and the prospective 

 load, the largest being nineteen feet long by seven inches wide. 

 When the combination beams were completed and ready for the floors 

 and roofs, heavy planks were firmly placed in position and securely 

 supported between the beams, the upper surface of these plank foun- 

 dations being adjusted on a level with the top surface of the molded 

 beams. These planks served as the bottom of the floor-molds, and, 

 after the beton forming the floor was hardened, they were removed. 



Channel-ways had been molded in the walls, on a line with the top 

 of the beams, for the purpose of supporting the outer edges of the 

 floors. 



Before the floors and roofs were laid, care was taken to cover all 

 the supporting surfaces with paper, to prevent the adhesion of floor 

 and roof sections to their supports. This precaution was necessary, to 

 permit the movement of the floors and roofs that would unavoidably 

 take place under varying temperatures and loads. 



A part of the experimental system contemplated an attempt to 

 warm the house by passing currents of heated air between the floors 

 and ceilings, and up through flues, made in close proximity to each 

 other, for that purpose, in the interior walls of the building; and it 

 was necessary to core out a liberal area of lateral openings through the 

 upper portion of the beams, in order to permit a free circulation of 

 heated air. The ceilings rested upon flanges projecting from the lower 

 portion of the beams, as shown in Fig. 1. 



Instead of using sand and gravel, or both, in combination with 

 cement, for floor and roof construction, the preliminary experiments 

 that proved the superior value of broken blue-stone for massive work, 

 led to the adoption of washed, fine screenings from the same material 

 for the floors and roofs, because its greater angularity insured a 

 stronger bond in the work than could be realized by using sand and 

 gravel. 



The proportions of materials used for this purpose were, one part 

 of Portland cement to two parts of the fine stone screenings. The 

 preparations being completed for laying down the floors, a thin course 

 of the beton was first put on, and evenly tamped down, to about an 

 inch in thickness, over the whole space intended to be covered. Then 

 rods of iron, five sixteenths of an inch in diameter, were placed both 

 longitudinally and laterally, at a uniform distance of eight inches 

 apart, over the whole surface. Then, on this, a final layer of two 

 inches in thickness was carefully tamped down. In about eight hours, 

 the beton was hardened sufficiently to allow the application of the top 

 surface, which was floated down with a half-inch coat of cement and 

 fine beach-sand mortar, made of equal parts of each. This completed 

 the finish, and made the whole thickness of the work three and a 



