| 1937 FORD Automobile Lighting Signal System Art |
| 1937 SIGNAL ENGINEERING COMPA Electromagnetic Bell |
| 1937 UNION SWITCH SIGNAL CO Track Circuit Art |
| 1937 HAY CLARENCE Signal Switch Patent Print Art |
| 1937 UNION SWITCH SIGNAL CO Recording Mechanism |
| 1937 FREDERICK P HOCKLAND Warning Signal Art |
| 1937 GEN RAILWAY SIGNAL CO Relay Patent Print |
| 1937 JOHNSON Railroad Crossing Signal Patent |
| 1937 WAGNER GEORGE Hotel Alarm Signal Patent |
| 1937 WESTERN RAILROAD SUPPLY COMPAN Traffic Signal |
| 1937 NEW YORK AIR BRAKE CO Pneumatic Signal System |
| 1937 SUBMARINE SIGNAL CO Depth Measurement Art |
| 1937 SIGNAL ENGINEERING COMPA Sound Producer Art |
| 1937 ELMER JOHNSON Warning Signal Patent Print |
| 1937 UNION SWITCH SIGNAL CO Signaling System Art |
| 1937 SUBMARINE SIGNAL CO Depth Sounding Art |
| 1937 DAVIS MOORE Light Signal Patent Print Art |
| 1937 GODFREY GORT Traffic Signal Patent Print |
| 1937 UNION SWITCH SIGNAL CO Railway Signaling System |
| 1937 UNION SWITCH SIGNAL CO Time Measuring Art |
| 1937 NEW HAVEN CLOCK Audible Signal Clock Art |
| 1937 KEITH JOHN Wigwag Signal Means Patent Print |
| 1937 GEN MOTORS CORP Sound Signal Patent Print |
| 1937 LEWIS Warning Signal Device Patent Print |
| 1937 SECO MFG COMPANY Wigwag Signal Means Patent |
| 1937 SUBMARINE SIGNAL CO Sound Producer Patent |
| 1937 WESTERN Reflector Type Signal Switch Stands |
| 1937 ELLIOT Distress Signal Electricallyoperated Clocks |
| 1937 HANNA Sound Producing Signal Art Print |
| 1937 WILLING JOSEPH Relay GEN RAILWAY SIGNAL CO |
| 1937 UNION SWITCH SIGNAL CO Railway Track Circuits |
| 1937 GODFREY Reflector Type Signal Switch Stands |
| 1937 AUTO FLAGGER CORP Railroad Crossing Signal |
| 1937 UNION SWITCH SIGNAL CO Railway Switch Controller |
| 1937 UNION SWITCH & SIGNAL CO Control System Art |
| 1937 BURRESS Vehicular Traffic Control Signal |
| 1937 UNION SWITCH SIGNAL CO Railway Switch Operating |
| 1937 SPARKS WITHINGTON CO Warning Signal Patent |
| 1937 CAMPBELL Pneumatic Signal System Patent |
| 1937 UNION SWITCH & SIGNAL CO Light Signal Art |
| 1937 GEN RAILWAY SIGNAL CO Switch Machine Railroads |
| 1937 WILSON MERCER Crossing Signal Patent Print |
| 1937 UNION SWITCH SIGNAL CO Railway Braking Art |
| 1937 GREGORY Railroad Crossing Signal Patent |
| 1937 PORTER Audible Signal Clock Patent Print |
| 1937 GEN RAILWAY SIGNAL CO Train Describer System |
| 1937 UNION SWITCH SIGNAL CO Speed Responsive |
| 1937 GEN ELECTRIC Signal System Patent Print Art |
| 1937 SUITS CHAUNCEY Signal System Patent Print |
| 1937 GEN RAILWAY SIGNAL CO Railway Signaling System |
| 1937 MOORE EDMUND Light Signal Unit Patent Print |
| 1937 UNION SWITCH SIGNAL CO Track Rail Contactor |
| 1937 UNION SWITCH SIGNAL CO Railway Signaling |
| 1937 GEN RAILWAY SIGNAL CO Light Signal Unit Art |
| 1937 UNION SWITCH SIGNAL CO Interlocking Control |
| 1937 SUBMARINE SIGNAL CO Sound Producing Mounting |
| 1937 SUBMARINE SIGNAL CO System Submarine Signaling |
| 1937 GENERAL RAILWAY SIGNAL CO. TRAFFIC CONTROL MANUAL |
| SMALL 1937 photo ~ SIGNAL HILL OIL WELLS Long Beach, CA |