288 FLOORS 



A very good floor for mills and factories is shown in Fig. 138. 



x- If ' Mafc/retf Afop/e Long/fUGf/fta/ 

 Transverse 



^~/"/7/?e Concrete of tar or aspha/t 

 "J" Concrete 



FIG. 138. 



The pitch or asphalt will prevent the decay of the plank and will 

 add materially to the life of the floor. Maple flooring makes the best 

 wearing surface for floors and should be used if the cost is not pro- 

 hibitive. 



The floor shown in Fig. 139 was constructed as follows : Two-inch 

 plank, matched and planed on one side, were laid on 3" x 3" chestnut 

 joists. The surface of the cinders was kept 2" away from the wood and 



this space was filled with lime mortar. After the surface of the cin- 

 ders had been graded, the 3" x 3" joists were held in place by stakes 

 nailed to the joists about three feet apart. The lime mortar was then 

 filled in around and slightly above the surface of the joists to allow for 

 shrinkage. Before laying the floor a thin layer of slaked lime was 

 spread over the surface. This floor in an eastern city cost about 85 

 cents per square yard ; and has a life of 10 to 12 years. 



Examples of Floors. The floor of the Locomotive Shop of the 

 A. T. & S. F. R. R., at Topeka, Kas., is as follows: The floor foun- 

 dation is formed of 6 inches of concrete resting on the natural soil well 

 tamped. On the concrete are laid 3" x 4" yellow pine stringers at 18- 

 inch centers, the whole being covered with 2-inch No. I hard maple, 

 surfaced on one side and two edges and milled for Y^" x i" pine splines. 



