Power for operating the B. R. T. system is now generated in two alternating-current plants with installed capacities as follows: Central (Third Av. & 2nd. St.) 16,500 kw. Williamsburg (Kent Av. & Rush St.) 182,500 kw. Power is generated and transmitted at 6600 volts, 25 cycles, three-phase. Owing to the diversified feeding system it is not possible to estimate the portion used by the elevated and surface lines. Power for the operation of the Manhattan lines is purchased from the Interborough Rapid Transit Co. _Substations_ For supplying 600 volts to the entire system the B. R. T. has in operation 98 synchronous converter units aggregating 142,500 kw. These units range in size from 500 to 4000 kw. each. Many of the stations feed both elevated and surface lines so that it is difficult to approximate the capacity available for the rapid transit service. _Distribution_ Current collection on all elevated and subway lines is from an over-running third rail. The following sizes of third rail are in use: Early Elevated lines 55 lb. (to be replaced with 80 lb.) Subway lines 80 lb. New Subway 150 lb. _Rolling Stock_ The New York Consolidated R. R. Company operates in subway and elevated service a total of 1550 cars each equipped with two motors and multiple unit control. These include the equipment operated over the New York Municipal lines through the new subways. 900 of the newest cars use GE-248 motors and weigh, fully equipped, about 45 tons with seats for 72 passengers. These new cars are operated in all motor car trains. Trains up to seven cars are operated in rush hour service and the minimum headways approximate two minutes. The maximum length of ride possible for a single fare is from Corona through the Broadway subway to Coney Island, about 21 miles. The maximum grade on the system is 5 per cent on the New York Municipal line. [Illustration: 4000-KW. SYNCHRONOUS CONVERTERS INSTALLED IN SOUTH 6TH STREET SUBSTATION] ------------------------------------------------------------------------ CHICAGO ELEVATED RAILROADS The present Chicago Elevated Railroads are an amalgamation of the four systems which up to 1911 were operated as independent lines. Under the unified system of operation a single fare takes the passenger from one end of the system to the other, except that north of Howard Street on the Evanston line an additional fare is collected. The longest continuous ride without change is from Wilmette to Jackson Park, a distance of 24 miles. The first elevated road, afterward known as the South Side Elevated, started operation in June, 1892, with steam engines. After the successful demonstration on the Intramural Railway this line was electrified; all steam equipment being withdrawn in 1898.