Dopo il 1913 altri fattori vennero inoltre presi in considerazione, e la forza ridotta a 1.000 libbre (4.400 newton, ovvero 450 chilogrammi-forza). ###>After 1913, other factors were also taken into account, and the force delivered was reduced to about 1,000 lbf (4,400 N or 450 kgf).