| Year | 1921 |
| Date | 01-Sep |
| Volume | 45 |
| Issue | 1,062 |
| Page | 176 |
| Category | Electronic |
| Part | |
| Title | Spark Coils for Wireless Telegraphy |
| Author | |
| Notes | The core primary and tube, showing construction of primary tube, condenser making, lathe polishing head used as a section winder, wax trough, waxed paper section papers, apparatus for winding, former & front plates |