Rear view of block signal post, showing transformer and instrument cases with doors open.

subways new york state new york railroad facilities illustrations rare book division interborough rapid transit the new york subway its construction and equipment rear view instrument cases interborough rapid transit company author rear view block post transformer instrument cases doors interborough rapid transit new york subway subway new york city high resolution new york public library

1904

New York Public Library

http://digitalcollections.nypl.org/

Creative Commons CC0 1.0 Universal Public Domain Dedication ("CCO 1.0 Dedication")