WANDERING HOUR DIAL. Sometimes called a 'Floating Hour Dial'. A semi-circular slit opening in the upper half of the dial reveals roman hour numerals, appearing one at a time and in ordinary succession. On the outer edge and beyond the slit are the minute graduations occupying the corresponding half-circle to the inner slit for the hour numerals, and marked 0 - 60 minutes. The hour numeral travels from left to right, indicating the minutes in its passage. On reaching the 60 minute mark, it disappears beyond the slit and is succeeded by the next hour numeral following in its wake. A third, and innermost semi-circle, is marked off in quarter-hours.

Wandering-hour watches were quite popular during the last quarter of the 17th century and during the earlier years of the 18th. A few were also produced at the end of the 19th and early 20th century. They are also called 'chronoscopes.'

WARNING. The preparatory operation of the striking mechanism occurring a few minutes before the striking is released on the hour. A wheel in the striking train (the 'warning wheel') carries a pin which is arrested and then released by the 'warning piece'.

WATCH PAPER. Embroidered cambric or muslin or printed papers that were placed in the backs of the outer case of pair-case watches. These served to prevent the back of the inner case becoming scratched and also took up any slackness between the two cases. Towards the end of the 18th century they also served as advertisements of the watchmaker or repairer. Many have sentimental rhymes or admonishing proverbs, and some gave the equation of time.

WINDING SQUARE. The squared end of the barrel or fusee arbor on which the key is fitted in order to wind the watch. A similar squared end is on the arbor carrying the hands, by which the hands may be set in key-winding watches; this is called the 'set-hand square'.

WORM WHEEL. See TANGENT SCREW.