38 



STEEL ROOF TRUSSES AND MILL BUILDINGS. 



CHAP. I. 



WINDOWS AND SKY LIGHTS. Mill and mine buildings should have an ample amount 

 of glazing in the form of windows and sky lights. Plane glass is made in two thicknesses, single 

 strength approximately ^ in. thick, and double strength approximatley f in. thick. Plane 



DOUBLE HUM WEIGHTED MHDOWS 



rr 

 ;*?! 



-vA*jL /JP 

 jg-W 



7*f 





. LJtitxr*/ farting Strip ft? Parting Strip 



rMuntin "g 



Use steel window post only when qirts. connect at side 



TYPEB- 



7j',3''l'',Z,J." 



r'f KBf&is. 



J \ 



i? 



/// ,///, _ rii/ i '* ft- '* 



% */f Ltt-Scnifilf t ,,, 



/< ' ^,,~v 5* \0vtto out of woodwork +3; to 4 ! 



J f KOUnu l* . _ *r o_ vi 





f /f^fl7 steef window post is used\ 

 \\~. .) [ omit for Type A 



--V yVhen steel 'window -post is not used, f]f*$' 



FIG. 29. DATA FOR DOUBLE HUNG WEIGHTED WINDOWS. 

 AMERICAN BRIDGE COMPANY. 



glass is graded as AA, A, and B. The AA grade being the best and the B grade the poorest. 

 Wire glass is T 8 ^ in. or \ in. thick and may be obtained with a smooth surface, with factory ribs 

 or prisms. For ordinary windows double strength glass gives very satisfactory results. For 

 sky lights and where windows are liable to be broken, wire glass should be used. The best 



