In considering the foregoing the fact that the prices relate solely to animals on farms should be borne in mind. They are doubtless somewhat lower than for animals elsewhere located, but prices of the latter have probably moved in the same direction and in about the same extent.[H] RAILWAY RATES IN 1897 AND AT PRESENT MEASURED IN MONEY. Throughout the foregoing discussion reference has frequently been made to what has been assumed to be a typical shipment, that is, a fifteen-ton carload of fourth class freight transported between Chicago and New York. The typical service rendered in moving this shipment would have brought the railways gross receipts of $105.00, in 1897 or in any of the intermediate years, and would bring the same amount now. The period in question, however, has witnessed many thousands of changes in railway rates on particular commodities and between particular points, and, confining the discussion for the present to the mere expression of rates in terms of money, it is necessary to inquire whether the general level of all rates has been raised or lowered and how far the change, if any is discovered, has gone in either direction. Now, it is manifestly impossible to correlate all rates in a single tabulation, and, giving to each its proper weight in the determination of a final average, thus establish definitely and with complete precision the relation between the money rates of 1897 and those at the present time. The number of different articles shipped and the great number of different points at which each article may enter into the aggregate of traffic movement or to which it may be destined, as well as the elusive character of the factors which would indicate the relative weight properly to be allowed to each separate rate, wholly preclude the adoption of such a method. Fortunately, however, American railway accountants long ago adopted a measure of traffic movement, which was later officially sanctioned by its adoption for the same purpose by the Interstate Commerce Commission, and which, when compared with the gross receipts from freight service, results in an average that throws great light upon the movement or absence of movement in the general level of the rates charged. When the weight of any shipment, expressed in tons, is multiplied by the distance which it is carried, expressed in miles, the resulting product gives a measure of the service performed, in units which are designated as "ton-miles." When the ton-miles (or ton-mileage) of all shipments are aggregated the total represents the sum of all services. The result of dividing the revenue from a particular shipment by its ton-mileage is the average rate per ton per mile for that shipment and if the sum representing the aggregate gross receipts from all railway freight services is divided by the aggregate ton-mileage of those services the quotient obtained is the average ton-mile rate for all services. During the period from 1897