AMOUNT OF LIGHT REQUIRED 



3 11 



ELEVATION 



i'xIj'Layxnsw 



' { ^?*y Block 



Mortised 

 Pulley 



SECTION 



PLAN 

 FIG. 155. DESIGN FOR WINDOW FRAME; WITH WEIGHTED SASH. 



It is common to specify that not less than 10 per cent of the ex- 

 terior surface of ordinary mill buildings and 25 per cent of the exterior 

 surface of machine shops and similar structures shall be glazed. One- 

 half of the glazing is usually required to be in the roof in the form of 

 skylights. With translucent fabric it has been found that the lighting 

 is good where 25 per cent of the roof is glazed. 



The present tendency in shop and factory design is to make as 



