> "...However, the system was repaired and pneumatic clocks continued to work until 1927, when the invention of accurate mechanical and electric clocks made the

> "...However, the system was repaired and pneumatic clocks continued to work until 1927, when the invention of accurate mechanical and electric clocks made the need for a central synchronization clock obsolete..." This is not really true, in that you may remember from your elementary or high school days that many places still have centrally synchronized clocks. When there are about 100 clocks distributed around a building, and not yet migrated to individually-kept radio/GPS/network time, the only staff-sanity preserving method of keeping them together is to use a central electronic pulse transmitted over the power lines (which the clocks are plugged into). If I recall right, there is an hourly pulse that tells the clocks to wait/speed up until the top of the hour is reached. Then there's a daily pulse that tells them to wait/speed up to reset to midnight!