The Block Signal and Train Control Board, seeing the need for accurate data in the signal field, started the tabulation of such statistics when it compiled and issued Block Signal Statistics as of January 1, 1908. After this board went out of existence, the Bureau of Safety of the Interstate Commerce Commission continued the collection and publication of these data yearly. Perhaps no better word picture can be given of what Dr. Robinson's invention has meant to the railroads than to present the story in the form of a table showing the miles of road and the track equipped with the track circuit since January 1, 1908. In addition to the table, the accompanying chart presents the information in a graphical form. [Illustration: Progress Chart of Automatic Signal Installations Since January 1, 1908.] Track Circuit Mileage for Automatic and Controlled Manual Signals in the United States as Taken from I.C.C. Reports ----------+-------------------+--------------------------------------- | Automatic | Controlled Manual +---------+---------+-------------------+------------------- | | | Miles of Road | Miles of Track | Miles | Miles +--------+----------+--------+---------- | of | of | Track |Continuous| Track |Continuous | Road | Track |Circuits| Track |Circuits| Track | | | at | Circuits | at | Circuits | | |Station | |Station | ----------+---------+---------+--------+----------+--------+---------- January 1,| 1908 | 10,819.3| 18,534.1| 726.7 | 212.0 | 2118.0 | 410.8 1909 | 12,174.3| 20,590.9| 407.6 | 572.2 | 978.0 | 1413.0 1910 | 14,238.9| 23,771.3| 385.8 | 491.5 | 953.5 | 1371.3 1911 | 17,709.8| 29,151.6| 483.9 | 439.4 | 1119.3 | 739.9 1912 | 20,300.0| 33,343.8| 402.0 | 295.9 | 955.6 | 496.0 1913 | 22,196.6| 36,873.0| 370.2 | 228.3 | 868.9 | 380.3 1914 | 26,569.3| 44,461.2| 275.7 | 180.3 | 625.3 | 281.6 1915 | 29,863.5| 49,442.1| 250.5 | 145.1 | 549.3 | 185.7 1916 | 30,942.5| 51,119.7| 255.1 | 125.1 | 549.6 | 179.3 1917 | 32,954.6| 53,799.8| 230.3 | 132.0 | 524.8 | 155.5 1918 | 35,193.1| 57,083.6| 208.1 | 131.2 | 451.6 | 154.8 1919 | 36,989.4| 59,458.2| 221.2 | 256.9 | 483.8 | 441.2 1920 | 37,968.8| 60,992.3| 196.3 | 129.2 | 413.3 | 151.4 1921 | 38,543.9| 61,744.5| 206.8 | 125.7 | 422.6 | 166.4 ----------+---------+---------+--------+----------+--------+----------