Train operation by signal indication.
Subtitle: I. The two principal methods of directing train movements.  II. Directing train movements by signal indication.
By: By Henry M. Sperry.
Publisher: H. M. Sperry
Published: 1920
Place of publication: New York
Language: eng
Number of pages: 28
Subjects: Railroads -- Trains; Railroads -- Signaling
Notes: "First published in the Railway age of June 4 and June 11, 1920."--p. 3.
Lettered on cover: Bulletin no. 3.