| Year | 1931 |
| Date | 26-Feb |
| Volume | 64 |
| Issue | 1,555 |
| Page | 204 |
| Category | Electrical |
| Part | 4 |
| Title | Simple Electrical Measurements |
| Author | A.H.A. |
| Notes | Diagram of gravity control, triangle of forces in gravity control movement, spring-controlled instrument movement, damping by fluid friction, by air dash-pot, by induced eddy currents |