| 1921 DODD ALVIN Audible Signal Patent Print Art |
| 1921 SUBMARINE SIGNAL CO Submarine Signaling Art |
| 1921 AUTOMATIC APPLIANCE Signal Mechanism Art |
| 1921 KRUPP AG Long Distance Signal Control Art |
| 1921 KRUPP AG Long Distance Control Signal Art |
| 1921 FRANK ROME Railroad Signal Patent Print Art |
| 1921 FINCH Signal Operator Spreading Rails Art |
| 1921 COLUMBIA Railway Signal Torpedo Art Print |
| 1921 DOWNEY Theft Signal Motor Vehicles Art |
| 1921 MORIN FRANK Fishing Signal Patent Print Art |
| 1921 HINCKLEY Signal Lantern For Locomotives Art |
| 1921 BOYD Classification Signal Locomotives Art |
| 1921 FRED Support For Signal Lamp Brackets Art |
| 1921 WILLIAMS Signal Railroad Crossings Art |
| 1921 SADIE WIDEMAN Car Signal Patent Print Art |
| 1921 WALTHER Long Distance Control Signal Art |
| 1921 SUBMARINE SIGNAL CO Diaphragm Mounting Art |
| 1921 PURITON MFG CORP Signal Patent Print Art |
| 1921 MARSICO GERARD Signal PURITON MFG CORP Art |
| 1921 WALTHER Long Distance Signal Control Art |