Page:Graphic methods for presenting facts (1914).djvu/266

 The Engineering Magazine

Fig. 198. Proposed Routes for a Comprehensive System of Passenger Subways for the City of Chicago

On this map each dot is carefully located to represent 200 of the population. A spot map of this kind, made to some scale whereby one dot represents several people, is essential to any reliable study of transit facilities. After the spot map is made, the transit routes can be laid out to give the best service possible. Short map pins with heads touching the paper can be used for dots on the original map