Sun-Dial, Portable—Made in different shapes and upon different plans small enough to carry about. The most common form was the ring dial, consisting of a metal ring with a hole in it through which the light fell upon an inside ring adjustable to the day and month. It required careful orienting to be dependable as a time-indicator.
Sun-Dials, Roman—The first dial in Rome was set up B. C. 293 near the temple of Quirinus by Papirius Cursor. It served ninety-nine years; then one more accurate was set up beside it. Before that, no time was noted except the rising and setting of the sun. Emperor Augustus erected a dial at Campus Martius. A dial captured in Sicily during the first Punic war was set up in the Forum about 263 B. C. and used for years before they learned that it was inaccurate in that latitude, being designed for the latitude of Sicily.
Sunk-Seconds—A dial in which the seconds circle is sunk below the rest of the dial. It allows the hour hand to be placed closer to the face thus making a thinner model possible.
Supplementary Arc—See: "Lifting Arc."
Sweep-Seconds—See: [Center-Seconds].
Table Roller—The roller of a lever escapement which carries the impulse pin.
Tell-Tale Clock—A clock by which a record is left of periodical visits of some one as a night-watchman.
Template or Timplet—One of the four facets that surround a cut gem.