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Setting Clocks 100 Years Ago

from the Time-Nuts mailing list (Nov 4, 2010):

—-Original Message—-

Subject: [time-nuts] Setting clocks 100 years ago

This evening I happened to hear the nearby church's bell tolling 10 pm, and thought that 100+ years ago this could have been the “official” time of the town, which maybe was used by people to set their own clocks (if any). But then I wondered, who told the priest what time it was? To what extent the clocks of two towns were expected to be close to one another? Does anybody know?

Antonio I8IOV


From: “Bill Hawkins”


The earliest purpose for mechanical clocks was religious, so they appeared in church towers in the 1600's. They were set by sundials. The 1800's brought the telegraph and precision telescopes. Once it was possible to transmit time signals at near the speed of light, and to determine star crossings with millisecond precision, time could be synchronized among those clocks the could be set electrically.

See “Einstein's Clocks, Poincare's Maps: Empires of Time” by Peter Louis Galison for a fascinating history of this era. Accurate maps could not be made without an accurate sense of time, provided by telegraph cables from a central clock in Paris.

The accuracy of pendulum clocks increased dramatically once true time could be known, leading to the Riefler and Shortt free pendulum clocks, where the free pendulum swung in a vacuum. These mechanical marvels gave way to the crystal oscillator in the 1930's.

Church clocks were fine with local sundial time until the railroads discovered the need to accurately schedule trains on the same track to avoid collisions, say in the 1850's. Central time standards were necessary to enforce a common sense of time over a wide geographic area, like the United States at the time. Paris had a pneumatic system for setting tower clocks across the city using pipes under the streets that carried pressure pulses from a central clock in 1880.

Synchronization was done with star-crossing observatories and telegraph signals driven by precision clocks that could keep steady time between one night's star crossing and the next. One of these was Goodsell Observatory at Carleton College, in Northfield, Minnesota, USA. See http://www.carleton.edu/departments/PHAS/astro/pages/history2.html

“From the 1870s until the Second World War the Carleton observatory was among the best and most prominent in the United States. It set time for all the major railroads from Chicago to Seattle.”

I visited the observatory a few years ago with a group of time enthusiasts. The remains of the telegraph board that distributed time far and wide were still there, but our guides couldn't tell us anything about them. Several accurate pendulum clocks were set around the concrete base of the telescope on the floor below it, but they were not in good repair. There was a Riefler clock in the basement that was missing the lower vacuum chamber because someone drilling holes for a computer network had drilled through a wall without looking to see what was on the other side. Corrosion has had its way with the mechanism since then.

The observatory building had been turned into classrooms and a faculty lounge in the room with the star crossing detector. No one seemed to know what they were treading on, or what prevented them from having more room. No one knew the purpose or value of the spare parts stores. I can't bear to go back there.

In short, church bells stopped being the time standard about 300 years ago. Heck, 100 years is only 30 years after I was born. I used to think my grandfather, born in 1880, had seen a lot of change. Now I've seen a lot of change, and lately none of it seems to be for the better.

Bill Hawkins

I hope someone appreciates the last two hour's work . . .

precision_timing/setting_clocks_100_years_ago.txt · Last modified: 2013/01/08 19:00 (external edit)
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