| Year | 1941 |
| Date | 21-Aug |
| Volume | 85 |
| Issue | 2,102 |
| Page | 158 |
| Category | Workshop |
| Part | |
| Title | Notes on Square Hole Drifts |
| Author | G.G. |
| Notes | Method of milling, sketches explaining the correct form of a square hole drift, dividing, under-raked edges, machine-made drifts |