Show 1131 TIO S OP H II SIGHT At t a height hl of ono one foot ool from the lie water wat wat- er r an nn object can bo ho seen at 13 wiles at six Mix feet elevation tho the range o of vi- vi 1 fion is increased 3 miles while white at 10 It feat the horizon Is 11 Increased to lo 16 miles Thin in iii clear went her puts tr great it limitations upon the Iho sl sight ht o of a submarine submarine submarine sub sub- marine periscope as all ihl allied ner- ner chant c vessels are arc keen keenly on the look Jool lookout out for 0 such |