172 



W. H. WAKREN. 



Fig. IV. f. 



Compression in units of -0008 inch on 20 inches. 



fi 9 12 15 18 21 24 27 



SO 



6 9 12 15 18 21 24 



Compression in units of "0008 inches on 20 inches. 



Fig. IV. g. 



