[148] An interesting illustration of such determination of separable or extra cost was the computation by which the movement expenses of a train load of 50 cars of grain, 80,000 lbs. to the car, from Buffalo to New York were fixed at $520. I. C. C. Reports, 1903, p. 397. Or again in the estimation of the costs of operation in the express service from New Orleans to Kansas City in the banana trade. I. C. C. Rep., No. 1235, 1908. The able Wisconsin Railroad Commission has carefully studied a number of such cases, notable in its Two-Cent Fare decision of 1906. [149] _Cf._ Tunell, Railway Mail Service, Chicago, 1901. [150] Personal correspondence. [151] Details in vol. II. [152] 13 I.C.C. Rep., 357. [153] 5 I.C.C. Rep., 299. [154] On raisins compared with citrus fruits: 22 I.C.C. Rep., 1. [155] Interstate Commerce Commission, No. 797. [156] More in detail in chap. IX. [157] Senate (Elkins) Committee, 1905, testimony of Mr. Bird, Traffic Manager of the St. Paul road. This is best measured, of course, by revenue per ton mile, chap. XII, _infra_. [158] Flour _v._ wheat, p. 135, _supra_. [159] P. 148, _supra_. [160] More in detail at p. 318, _infra_. Also Hammond, Rate Theories of the I. C. C., 1911, p. 32. [161] U. P. Tea Co.; I.C.C. Rep., No. 1569, 1908. CHAPTER VI PERSONAL DISCRIMINATION Rebates and monopoly, with attendant danger to carriers, 185.-- Personal discrimination defined, 188.--Distinction between rebating and general rate cutting, 188.--Early forms of rebates, 189.--Underbilling, underclassification, etc., 190.--Private car lines, 192.--More recent forms of rebating described, 195.--Terminal and tap-lines, 196.--Midnight tariffs, 197.--Outside transactions, special credit, etc., 198.--Distribution of coal cars, 199.--Standard Oil Company practices, 200.--Discriminatory open adjustments from competing centres, 202.--Frequency of rebating since 1900, 204-6.--The Elkins Law of 1903, 205.--Discrimination since 1906, 207.--The grain elevation cases, 211.--Industrial railroads once more, 212. The philosophy of rebating has perhaps never been better described than in the following quotation from the Cullom Committee investigation of 1886: