Slow beat conversion.
MOVEMENT : Signed (THOS. YATES, Preston) and numbered 710. The balance cock foot is marked “PATENT”. Lever fusee movement, in good condition and running well though missing the removable brass dustcap.
DIAL : Signed cream enamel. Perfect condition and marked :
SOCIETY OF ARTS
CASE : Silver case, hallmarked for Chester, 1848, maker CJ. Gold hinges.
The case is in good condition. The bezel and cover close nicely and the hinges are fine. No damage or repairs, just even wear to the back and milled band. The mineral crystal has one small chip right on the bezel.
Thomas William Yates patented a variety of slow beat watches between about 1846 and 1880, with beat speeds ranging from 7200 to 11200. The earlier examples (as this) used the slowest (half second) beat of 7200. The serial number for this watch (710) places it correctly for 1848, for the documented Yates slow beat serial numbers. The train counts are as follows :
2nd wheel 64
3rd wheel 60 3rd pinion 8
4th wheel 56 3rd pinion 8
escape 15 escape pinion 7
which gives a standard beat of 14400. A number of Yates watches are known to have been converted from 7200 to 14400, to update the escapements. I believe this watch has been converted from a half second slow beat, by reducing the escape wheel pinion to 7 leaves (from 14) and probably replacing a heavier balance wheel. See Antiquarian Horology, Vol. 15, p144.