DETAILS OF DESIGN 177 



concrete foundation are quite common; while in buildings where men 

 have to work at machines the favorite floor is a wooden floor on a foun- 

 dation of cinders, gravel, or tar concrete. Where concrete is used for 

 the foundation of a wooden floor it should be either a tar or an asphalt 

 concrete, or a layer of tar should be put on top of the cement concrete 

 to prevent decay. Concrete or cement floors are used in many cases 

 with good results, but they are not satisfactory where men have to 

 stand at benches or machines. Wooden racks on cement floors remove 

 the above objection somewhat. Where rough work is done, the upper 

 or wearing surface of wooden floors is often made of yellow pine or oak 

 plank, while in the better classes of structures, the top layer is com- 

 monly made of maple. For upper floors some one of the common types 

 of fireproof floors, or as is more common a heavy plank floor supported 

 on beams may be used. 



Care should be used to obtain an ample amount of light in build- 

 ings in which men are to work. It is now the common practice to make 

 as much of the roof and side walls of a transparent or translucent ma- 

 terial as practicable ; in many cases fifty per cent of the roof surface is 

 made of glass, while skylights equal to twenty-five to thirty per cent 

 of the roof surface are very common. Direct sunlight causes a glare, 

 and is also objectionable in the summer on account of the heat. Where 

 windows and skylights are directly exposed to the sunlight they may- 

 best be curtained with white muslin cloth which admits much of the 

 light and shades perfectly. The "saw tooth" type of roof with the 

 shorter and glazed tooth facing the north, gives the best light and is 

 now coming into quite general use. 



Plane glass, wire glass, factory ribbed glass, and translucent fabric 

 are used for glazing windows and skylights. Factory ribbed glass 

 should be placed with the ribs vertical for the reason that with the ribs 

 horizontal, the glass emits a glare which is very trying on the eyes of 

 the workmen. Wire netting should always be stretched under sky- 

 lights to prevent the broken glass from falling down, where wire glass 

 is not used. 



