Here's a brief tour of the oldest known mechanical clock, which is at the Salisbury Cathedral in the UK. It's both simple and elegant, considering what tools and technology were available in 1386!
For the striking side, the big part at the end of the wheel train, with the two blades, is the “fan fly” or just “fly”, and serves as an air brake to keep the strike train from over speeding when it is running. The part which actually counts the hours is the “count wheel”, and the lever which falls into it to shut off the striking train after it has counted the hours, is the “count lever”. Count wheel striking is very simple and early, but can get out of sync with the time train if it fails to trip on the hour, or is tripped more than once before the next hour, so in the 1600s an English clockmaker invented “rack and snail” striking which works off the hour hand to keep the striking in sync with the hands. Both count wheel striking and the verge and foliot escapement are so old, we don’t know who invented them or what year. I’m not sure they’re even sure the name of the builder of this clock. Thanks for sharing!
The top part is called a “verge and foliot” escapement. The arrangement of the two escape pallets on their arbor is called the “verge” and the escape wheel in this kind of escapement is called a “crown wheel” due to the shape. The actual swinging timekeeper at the top is the actual “foliot”. This system predated the invention of the pendulum by at least 350 years, and was considered good enough for those days.
Apparently, when this clock was discovered the original escapement was replaced with a pendulum. I don't necessarily understand the point since there's no dial and it just rings a bell. Why would there need to be minute by minute accuracy? If the bell chimes 12 and it's around noon, isn't that good enough?
Looks like it was the great grandfather of the industrial revolution of the 18th century, and with those different sized notches - rudimentary programming. Impressive
I just found an old film from 1956 when this clock was first restored back to its original state, here: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-BBHvAzkXaKc.html
The earliest mechanics clocks did not have dials. At their best, they were only accurate to within about 15 minutes per day. What they did was strike a bell on the hour. The earliest ones probably did this once an hour from the time train, called a “passing strike”. Later, someone invented the striking train, and there are documents telling of the existence of a striking clock in Italy in the early 1300s that could count up to 24 strikes on the bell per hour for 24 hours a day. This must have been tedious however, so shortly thereafter most clocks only struck up to 12.
Dials with a single hour hand (and sometimes also astronomical functions showing movements of the stars/heavens, Moon etc) were introduced to mechanical clocks probably around the 1300s. Of course both sundials and mechanical hand cranked astrolabes such as the Antikythera Mechanism, date back to antiquity. But non water powered, automatic mechanical clocks were new in the late Medieval period. Clocks were not accurate enough to justify minute hands until the 1600s. Seconds hands were introduced around the 1700s. An outstanding exception is the clock made in the 1500s for/by Mr Burgi, I think (don’t have my books with me), which features a “cross beat” escapement. But that clock was basically a one off.
