| Year | 1956 |
| Date | 23-Feb |
| Volume | 114 |
| Issue | 2,857 |
| Page | 325 |
| Category | Correction |
| Part | |
| Title | Case-Hardening in the workshop |
| Author | Duplex |
| Notes | An electric muffle furnace and pyrometer, suitable steel, preparing the work, heat treatment, preventing rust, tempering, case-hardened knurling wheel and cutter, toolmaker's clamp |