| Year | 1920 |
| Date | 18-Nov |
| Volume | 43 |
| Issue | 1,021 |
| Page | 414 |
| Category | Electrical |
| Part | |
| Title | Electric Welding with Direct and Alternating Current |
| Author | Calculus |
| Notes | Spot welder fitted with seam welding attachments, another type by A1 Manufacturing Co., a large butt welder |