3 



CHART OF BAC. COLI COMMUNIS. 



15 Ml N. 



30 IVl I N. 



45 M I N. 



60 IVl I N. 



75 MIN. 



90 MIN. 



105 Ml N. 



I20 M I N. 



The different colors on the chart represent the amount of protection afforded by glass of the same color. 



10tlltCOUTH.g*mMOII£ 



