EFFECTIVE BACK 



RADIATION (Q^) 



cal /cm^/day 



JULY 

 1961- 1971 MEAN 



180°* 175 W 170 W 165 W 160 W 155 W I50 W 145 W i«0 W 135 W 130 W i25 W 120 W IPS W. 



94 



