Dating french clocks
This type of hood top carried on from 1740 right to the end of the brass dial period.
Japanned, or Lacquered cases were fashionable from 1725 to 1770, some Northern examples are around, but many were stripped back to the wood years ago, when our climate caused the finish to deteriorate badly.
One-handed clocks continued to be made in country areas for a long time, so one hand is not an absolute guarantee of an early clock, but is a good guide.
Village life was very conservative, and the people living in villages at this time still had no real need of to the minute time.
Very few Northern makers used this movement, it was essentially the same as the even earlier Lantern Clock movement.
Northern makers had no tradition of making these clocks, so used the normal plated movement (vertical plates, horizontal pillars) from the start of their clockmaking.
From now on the timekeeping of clocks improved by a huge amount using the longer pendulum and "anchor" escapement.
Around the same period, with a slightly larger dial and a wooden hood to keep the dust out of the clock movement.
There are exceptions to these sizes of course, but they are a good general guide when taken with other features.
A "bird-cage" movement (it has vertical pillars and the plates are horizontal top and bottom) is often taken to be a sign of an early clock.
This is not guaranteed however, in Southern England the clockmakers continued to make this type of movement from the start right through to 1820.
If your grandfather clock has a brass dial, it was probably made in the period between 16, and most likely between 17. Most of them only had one hand, because the average person had no need of knowing the time to the nearest minute, and with a bit of experience you can tell the time to the nearest five minutes on one of these early clocks.
By 1730 the vast majority of grandfather clocks had two hands, for the hours and minutes.