| Year | 1931 |
| Date | 30-Apr |
| Volume | 64 |
| Issue | 1,564 |
| Page | 414 |
| Category | Testing |
| Part | 2 |
| Title | The Use and Construction of a Simple Stroboscope |
| Author | Harold E.Cowley |
| Notes | An instrument which enables the observer to perceive the motion of rapidly moving mechanisms. Finish, operation, disc or shutter, component parts |