786 THE POPULAR SCIENCE MONTHLY. 



Tlie bulletins of the census furnisli, to some extent, the sta- 

 tistics relating to rapid transit in cities, and of the relative econ- 

 omy of different motive powers used on street railways. These 

 bulletins have been prepared by Mr, Charles H. Cooley, special 

 agent for rapid transit facilities in cities, under the immediate 

 direction of that skillful statistician and economist, Mr. Henry C. 

 Adams, special agent for transportation, and from them we learn 

 the growth of rapid transit facilities during the ten years from 

 1880 to 1889, inclusive, in cities having over fifty thousand in- 

 habitants. The special experts have selected cities on a basis of 

 an estimate of population made at the time the compilation of the 

 tables was begun. 



The full reports of the statistics of the equipment of all roads 

 furnishing rapid transit facilities, and of their operations for the 

 single fiscal year ending 1890, are being collected, and the census 

 authorities will present them in future exhibits. 



Prof. Adams announces, and with truth, that street railways 

 have never before been brought within the scope of the census 

 statistics of transportation, and he points out the peculiar difficul- 

 ties which were met with in collecting the facts already presented. 

 Some of these difficulties arose from the ambiguity of designa- 

 tion, as " length of line," " length of single track," and " length of 

 double track," when applied to street railways ; and on account of 

 such ambiguities the attempt has been made to fix upon some 

 definite nomenclature by which careful returns can be secured. 

 The conclusion is, that " length of line " means length of road- 

 bed, or, in case of railways running entirely upon streets, the 

 length of street occupied ; that " length of single track " means 

 the length of that portion of the road-bed or street laid with one 

 track only ; and that " length of double track " means the length 

 of that portion of the road-bed or street laid with two tracks. In 

 determining the total length of tracks, switches and sidings have 

 been included, and thus double track has been reckoned as two 

 tracks. 



On December 31, 1889, 476 cities and towns in the United 

 States possessed rapid transit facilities, the total number of rail- 

 ways in independent operation being 807. Many railroads, how- 

 ever (and the number is stated at 286, having a total length of 

 3,150-93 miles, and 13, having a total length of 13575 miles), have 

 as yet made no report ; while in six the returns received were so 

 imperfect that it was necessary to supplement them by approxi- 

 mations. This statement accounts for the bulletins not present- 

 ing statistics for a series of years for the whole number of rail- 

 roads in the country, and m cities have been selected for which 

 the reports are comparatively complete. Suburban lines tribu- 

 tary to large cities, but without their corporate limits, as well as 



