Two page spreads each containing a project having to do with time. Some are pretty challenging. The principles are not explained fully, but there are other books for that. The later projects are a bit of a stretch because too conceptual. The instructions for the projects are kind of incomplete, but the book compensates by having a large number of pictures.

1. A year long calendar showing duration of day and night.
2. A simple orrery without a drive train.
3. A perpetual calendar, good from 1600 to 2299. This kind of design is actually marketed as a desk toy here and there.
4. A paper globe.
5. A time zone cylinder. It is another mechanical computer, allowing the determination of relative time.
6. A quadrant, to determine elevations generally, and also latitude from the elevation of the north star.
7. A sundial.
8. A universal sundial.
9. A nocturlabe.
10. A candle clock.
11. A water clock.
12. A pendulum clock.
13. An electronically driven large face clock, you need to cannibalize a smaller clock from this.
14. Running video images backwards.
15. An activity log.
16. Make your own time capsule.
17. A geologic time spiral, showing the various eras.
18. A potted plant.
19. A project about the speed of light.
20. A project about relativity. ( )