[55] Investigation in 12th Ann. I.C.C. Rep., 561.
[56] From Report of Commission to Investigate the Postal Service, 1901, p. 220; brought down to 1906 when local disturbances in wages, other costs of operation and rates outweigh all general considerations.
[57] Between 1890 and 1910 freight ton mileage rose three times over. Operating expenses grew by about two and one-quarter times.
[58] Cf. data as to revenue per ton mile on p. [413], infra.
[59] Other data as to density on p. [413], infra.
[60] Also known as "average tons per train mile." Obtained by dividing the ton mileage by the sum of the freight and mixed train miles.
[61] Cf. Quarterly Journal of Economics, XVIII, p. 299; on per diem reform. Also, Railway Age, 1903, p. 136; 15th Ann. Rep., I. C. C., p. 79; and Circular Letters, 1901, Chicago Bureau of Car Performances.
[62] Using the right hand scale.