A whole issue of Popular Mechanics could be filled on the subject of dials and even then only give a general outline. Astronomy, geography, geometry, mathematics, mechanics, as well as architecture and art, come in to make “dialing” a most charming scientific and intellectual avocation.
Fig. 7—“Time-Boy” of India
During the night and also in cloudy weather the sundial was useless and we read that the priests of the temples and monks of more modern times “went out to observe the stars” to make a guess at the time of night. The most prominent type after the shadow devices was the “water clock” or “clepsydra,” but many other methods were used, such as candles, oil lamps and in comparatively late times, the sand glass. The fundamental principle of all water clocks is the escape of water from a vessel through a small hole. It is evident that such a vessel would empty itself each time it is filled in very nearly the same time. The reverse of this has been used as shown in [Fig. 7], which represents the “time-boy” of India. He sits in front of a large vessel of water and floats a bronze cup having a small hole in its bottom in this large vessel, and the leakage gradually lowers this cup till it sinks, after which he fishes it up and strikes one or more blows on it as a gong. This he continues and a rude division of time is obtained,—while he keeps awake!
Fig. 8—“Hon-woo-et-low” or “Copper Jars Dropping Water”—Canton, China
