| 1931 WALDEN HAROLD Game Apparatus Patent Print |
| 1931 HYLAND Life Boat Launching Apparatus Patent |
| 1931 HEIDBRINK Football Game Apparatus Patent |
| 1931 RICHARDS Signaling Apparatus Patent Print |
| 1931 LA RIZZA Amusement Apparatus Patent Print |
| 1931 BAHR Ship Raising Apparatus Patent Print |
| 1931 MEARS Speed Control Apparatus Patent Print |
| 1931 STOKER Train Indicating Apparatus Patent |
| 1931 BUTLER Electric Signaling Apparatus Patent |
| 1931 ERNST Sound Transmitting Apparatus Patent |
| 1931 COLEMAN Railway Interlocking Apparatus Art |
| 1931 EVANS Car Stopping Apparatus Patent Print |
| 1931 YOUNG Railway Track Circuit Apparatus Art |
| 1931 JOSEPH Game Apparatus Patent Print Art |
| 1931 MAHONEY Amusement Apparatus Patent Print |
| 1931 WATLING Amusement Apparatus Machine Patent 18059 |
| 1931 HERRICK Initiating Apparatus Patent Print |
| 1931 WOLFGANG Speed Responsive Apparatus Patent |
| 1931 GEBERT ALBERT Game Apparatus Patent Print |
| 1931 FRED J BROWN Life Saving Apparatus Patent |
| 1931 ALLEN Train Indicating Apparatus Patent |
| 1931 SPAFFORD LEWIS Game Apparatus Patent Print |
| 1931 HERBERT Train Control Apparatus Patent |
| 1931 CLAUSEN Exercising Apparatus Patent Print |
| 1931 ALEXANDER Game Apparatus Patent Print Art |
| 1931 DAVID Protective Apparatus For Athletes Art |
| 1931 MALLARD LOGAN Game Apparatus Patent Print |
| 1931 TALBERT Pin Resetting Apparatus Patent |
| 1931 YOUNG Electrical Controlling Apparatus Art |
| 1931 ARMAND NADEAU Game Apparatus Patent Print |
| 1931 LUSSE Amusement Car Apparatus Patent Print |
| 1931 CLIFFORD Speaking Tube Apparatus Patent |
| 1931 MAURITZ Game-Scoring Apparatus Patent Print |
| 1931 GRAY Railway Switch Apparatus Patent Print |
| 1931 RENN GEORGE Game Apparatus Patent Print Art |
| 1931 DAVIS JR Siphon Apparatus Patent Print Art |
| 1931 MAY FINN Submergible Apparatus Patent Print |
| 1931 BUTRIDGE Railway Signaling Apparatus Patent |
| 1931 DARRAH Light Measuring Apparatus Patent 11087 |
| 1931 ROBINSON Submarine Safety Apparatus Patent |
| 1931 JOSEPH LEBLANC Swimming Apparatus Patent |
| 1931 EDWIN Electrical Fishing Apparatus Patent |
| 1931 FRIEDRICH Filled Bag Closing Apparatus Art |
| 1931 ANDRE Aquatic Amusement Apparatus Patent |
| 1931 TRUST Pin Setting Apparatus Patent Print |
| 1931 LEVITT DAVID Game Apparatus Patent Print |
| 1931 SPARKS Apparatus For Manufacturing Bags Art |
| 1931 HICKS RAYMOND Timing Apparatus Patent Print |
| 1931 ABRAHAM Submarine Salvage Apparatus Patent |
| 1931 WILLIAM TURRALL Game Apparatus Patent Print |
| 1931 SHOEMAKER Exercising Apparatus Patent Print |
| 1931 O'HAGAN Railway Track Circuit Apparatus Art |
| 1931 PARRILL Train Indicating Apparatus Patent |
| 1931 VANHORN Remote Control Apparatus Patent |
| 1931 SWAIN RODNEY Golf Game Apparatus Patent |
| 1931 HARRIS Air Circulating Apparatus Patent |
| 1931 VINCENTY SZAMIER Diving Apparatus Patent |
| 1931 VANHORN Railway Interlocking Apparatus Art |
| 1931 MCGEE Life Saving Apparatus Patent Print |
| 1931 GILSON Motor Control Apparatus Patent Print |
| 1931 HOPPES Playground Apparatus Patent Print |
| 1931 HARRY Educational Game Apparatus Patent |
| 1931 PETER CLAUSEN Game Apparatus Patent Print |
| 1931 ROBERDS Cycle Driving Apparatus Patent |
| 1931 RIMEDIO Plant Spraying Apparatus Patent |
| 1931 ADVANCE MACHINE CO Game Apparatus Patent |
| 1931 ZIERDT Electrical Apparatus Patent Print |
| 1931 MCKEEN Wheel Counting Apparatus Patent |
| 1931 DOS SANTOS Amusement Apparatus Patent Print |
| 1931 HOWCOTT HARLEY Pumping Apparatus Patent |
| 1931 MELCHER Air Conditioning Apparatus Patent |
| 1931 KOHLER Staff For Rotating Apparatus Patent |
| 1931 CRAGO Electrical Translating Apparatus Art |
| 1931 LUZERN Amusement Apparatus Patent Print Art |
| 1931 HARTLEY Railway Signaling Apparatus Patent |
| 1931 HEINA Portable Radio Apparatus Patent Print |
| 1931 LIGHT Sanding Apparatus For Locomotives Art |
| 1931 EARLEY MARTIN Game Apparatus Patent Print |
| 1931 MCGARRY Railway Switch Apparatus Patent |
| 1931 MCGINNESS Freight Handling Apparatus Patent |