Hal Murray wrote:
> where do you get the time?
The new years celebrations last night remind me of another source of
time: time balls.
Although a bit of nostalgia these days or even a joke, time balls were
clever, precise, and a critical part of naval infrastructure in the 19th
century, lasting well into the 20th century, and still operational daily
in Greenwich (not right now due to refurbishment). It falls into the
category of "time dissemination"; you know, WWV, GPS, UTC, NTP, and all.
The sound of church bells gave approximate time, partly because their
use case didn't require high precision and partly because sound travels
only one foot per millisecond. Related: starter pistols at track events;
clapperboards on movie sets; timing thunderstorms with lightning.
But light, as you know, travels literally a million times faster, one
foot per nanosecond. Thus the optics of a time ball solved the latency
problem of setting chronometers onboard ships in the bay. Fun fact: The
Beagle (of Charles Darwin fame) carried 25 chronometers. This is every
time nuts justification for having so many clocks at home. ;-)
----
If you want a fun timely project I'm waiting for a time nut to make a
GPS controlled desktop Arduino time ball. With clever design it could
re-arm itself and mark the precise time as often as once a minute
instead of once an hour or once a day.
Alternatively, if you allow the ball to free-fall 16 feet it takes
exactly one second. With clever design and multiple balls you could make
a continuous 1BPS (one ball per second) clock where each ground hit
exactly triggers the next ball release. This would get you front page on
hackaday. Lots of time nut fun looking at jitter and drift, at
temperature and pressure effects. And of course the ADEV would be
priceless. Seriously, some mechanical clocks teach you more about the
art of clock measurement and data analysis than a boring atomic
frequency standard or GPSDO.
Welcome to 2022, and may we all have a better time this year.
/tvb
Time ball rabbit hole:
https://en.wikipedia.org/wiki/List_of_chronometers_on_HMS_Beagle
https://en.wikipedia.org/wiki/Ship%27s_chronometer_from_HMS_Beagle
https://en.wikipedia.org/wiki/Time_ball
https://www.bbc.com/news/uk-england-humber-58559814
"Time balls: The rise and fall of a timekeeping icon"
https://www.nytimes.com/2004/12/30/opinion/a-brief-history-of-time-balls.html
"A Brief History of Time Balls"
https://nmmc.co.uk/wp-content/uploads/2016/04/120330_The_Falmouth_Timeball.pdf
"The Falmouth Time Ball", by Ronald S Hawkins [ superb historical &
technical details ]
https://hs-ny.org/schedule/2019/5/6/the-ups-and-downs-of-the-greenwich-time-ball-an-overview-of-its-history-mechanics-and-upkeep
https://youtu.be/ubvmCWet6iU
https://journals.sagepub.com/doi/abs/10.1177/002182868101200301
"The First Time Balls"
Journal for the History of Astronomy
https://adsabs.harvard.edu/full/1970JBAA...80..208H
"The Story of Greenwich Time"
https://www.bbc.com/travel/article/20191212-the-invention-that-inspired-a-new-york-tradition
"The invention that inspired a New York tradition"
https://www.xyht.com/gnsslocation-tech/the-clocks-at-the-center-of-the-universe/
"The Clock(s) at the Center of the Universe"
----
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