| Year | 1917 |
| Date | 19-Apr |
| Volume | 36 |
| Issue | 834 |
| Page | 250 |
| Category | Electrical |
| Part | |
| Title | Variable Speed Dynamos |
| Author | "Calculus" |
| Notes | Compounded dynamo, with opposing winding connected across a resistance, variation of field strength, auxiliary brush method of regulating, resistance between main & auxiliary brushes, dynamo with wound & unwound poles, vibrating contact method |