Precision Regulators

Precision Regulators

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18th Century


- The average mechanical clock could meet the general public's timekeeping needs.

- The scientific community, however, needed a much higher level of precision in their laboratories and observatories. Clockmakers sought to make ever more precise clocks.
- It was already known that temperature affects clock metals, diminishing timekeeping accuracy.

- In 1715, George Graham, an English clockmaker, did a great deal of research into the thermal reactions of different metals, hoping to find two metals whose rates of expansion would "compensate," or cancel one another out. He found that steel and the viscous metal mercury canceled each other out. He introduced a mercury-compensated pendulum in 1722.
- As clockmakers combined the technology of metals with new technological designs, timekeeping accuracy continued to improve.

- Thomas Tompion, the father of English clockmaking, made his first precision clock in 1676 for the Royal Observatory in Greenwich, England. It kept time to within two or three seconds per day.

- About fifty years later, John Harrison, inventor of the marine chronometer, built a regulator that was allegedly accurate to within one second per month.




- The Riefler Company of Germany was making timekeepers accurate to within .01 seconds per day. This was due to improved mechanics and materials, and new case designs.

- In order to keep pressure, temperature, and humidity as constant as possible, manufactures put precision clock movements in airtight cases called tanks. These tanks were then often placed in designated clock vaults.

- The accuracy of these clocks was not fully appreciated right away, as scientists had not yet defined sufficiently small increments of time. For instance, precision clocks produced by W.H. Shortt in the 1920s were believed to keep time within two milliseconds (.002) a day, but when one of these was tested in 1984, it was found to keep time to within 200 microseconds a day, or ten times more accurate than previously believed.