| Year | 1940 |
| Date | 03-Oct |
| Volume | 83 |
| Issue | 2,056 |
| Page | 263 |
| Category | Hot Air |
| Part | |
| Title | Practical Notes on Hot Air Engines |
| Author | "Artificer" |
| Notes | Side elevation and section of Heinrici engine, diagrams showing relative piston and displacer positions at various phases of the cycle, efficiency of hot-air engines |