| Year | 1930 |
| Date | 08-May |
| Volume | 62 |
| Issue | 1,513 |
| Page | 435 |
| Category | Horology |
| Part | |
| Title | A Perpetual Calendar |
| Author | Geo. Gentry |
| Notes | With some notes on making it, and driving it electrically. Dial, details of the movement, case showing operating knob, counting gear, day-date registering action, week-day register gear, star ratchet, month-wheel gear, lunar year gear, month-wheel, leap-year turret, month-wheel control finger on the notched wheel, proportions of the lunar work disc |