H4

Went to the Royal Museums at Greenwich today to visit the longitude exhibition that closes next Sunday after a six months run.
This is H4, made by John Harrison between 1755 and 1750, incredibly complex yet brilliant in its simplicity - the balance wheel and escapement.
The 5 ticks per second has been a feature of every chronometer since until the advent of Bulova and quartz.
A great story well told.
Harrison took 4 years to make it. A couple of modern day watchmakers made a replica and it took 10 years! Mind you they probably had to earn a living while they did it!