Manual of recommended practice for railway engineering and maintenance of way (1905)
American Railway Engineering and Maintenance-of-Way Association · Chicago, Ill. : The Association · leaf 152
for either two or three indica-tions, and is suitable for those roads having red for stop, green forcaution and white for proceed or no orders. Furthermore, it isadaptable for roads desiring to be more economical and put two armson one mast for both directions, because the top of the mast can… … <^ H: i3 ^ Semaphore Arm for TelegraphBlock Signal. Two Position.
Railroad engineering · Railroads
Internet Archive · Northeastern University Library · Public Domain Mark 1.0. Free to use for anything.
