Ship's clocks @ The Royal Society
With the benefit/handicap of Adam Savage (cross out the not wanted)
https://www.youtube.com/watch?v=cj3ZUeMVPCs
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
Hi Poul:
Do you have any information about the tripod platform John Emeaton designed for the clock?
https://en.wikipedia.org/wiki/John_Smeaton
It's my understanding that the clock would need to be regulated as to it's rate because of local gravity and set to the
correct time prior to making Venus/Sun transit measurements. All that done by astronomy I'm guessing this would be made
more fool proof if sidereal time was used.
PS Part of the design of the Western Union clocks is a parking space for the pendulum to be used when shipping. It's
too bad that people today don't know about it and in some cases destroy clocks.
https://prc68.com/I/SWCC2.shtml#mickiecat1
https://en.wikipedia.org/wiki/Transit_of_Venus#History_of_observation
--
Have Fun,
Brooke Clarke
https://www.PRC68.com
axioms:
- The extent to which you can fix or improve something will be limited by how well you understand how it works.
- Everybody, with no exceptions, holds false beliefs.
-------- Original Message --------
With the benefit/handicap of Adam Savage (cross out the not wanted)
https://www.youtube.com/watch?v=cj3ZUeMVPCs
On Sat 2023-07-01T14:48:22-0700 Brooke Clarke via time-nuts hath writ:
It's my understanding that the clock would need to be regulated as to it's
rate because of local gravity and set to the correct time prior to making
Venus/Sun transit measurements. All that done by astronomy I'm guessing
this would be made more fool proof if sidereal time was used.
The clock would not need to be regulated any more than a chronometer
on board a ship was regulated. Through the end of the 20th century
the Navy manuals for Quartermaster said that a ship's chronometer is
set at the maintenance shop before being carried to the ship and
it is never reset. The quartermaster must keep a log of how much
the chronometer deviates from true time.
For the timing of the transit the clock only needed to be regular, not
to be correct. The logs of the observations before and after would
allow the transit contact times to be determined by interpolation
using the clock and the logs of how far off that clock was in the days
before and after the transit.
--
Steve Allen sla@ucolick.org WGS-84 (GPS)
UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855
1156 High Street Voice: +1 831 459 3046 Lng -122.06015
Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m
On 7/2/23 7:54 AM, Steve Allen via time-nuts wrote:
On Sat 2023-07-01T14:48:22-0700 Brooke Clarke via time-nuts hath writ:
It's my understanding that the clock would need to be regulated as to it's
rate because of local gravity and set to the correct time prior to making
Venus/Sun transit measurements. All that done by astronomy I'm guessing
this would be made more fool proof if sidereal time was used.
The clock would not need to be regulated any more than a chronometer
on board a ship was regulated. Through the end of the 20th century
the Navy manuals for Quartermaster said that a ship's chronometer is
set at the maintenance shop before being carried to the ship and
it is never reset. The quartermaster must keep a log of how much
the chronometer deviates from true time.
For the timing of the transit the clock only needed to be regular, not
to be correct. The logs of the observations before and after would
allow the transit contact times to be determined by interpolation
using the clock and the logs of how far off that clock was in the days
before and after the transit.
As we say in the interferometric measurement business: Knowledge not
control.
On Sat, Jul 1, 2023 at 2:06 PM Poul-Henning Kamp via time-nuts
time-nuts@lists.febo.com wrote:
With the benefit/handicap of Adam Savage (cross out the not wanted)
https://www.youtube.com/watch?v=cj3ZUeMVPCs
At 12:06, I wonder if Adam is prompting the curator to explain the
fusee? Unfortunately, he doesn't know.
The conical shape of the cylinder the chain wraps around is meant to
equalize the torque from the mainspring as it winds down. It was a
major horological invention and used for hundreds of years. The size
and thickness of the fusee mechanism, and the cost and durability of
the tiny chain, were major disadvantages in pocket watches and
wristwatches. The development of escapements that were less sensitive
to the driving torque replaced it.
Also at 3:52 Adam says one metal expands and the other contracts with
temperature. Actually they both expand but at different rates. The
"gridiron" pendulum developed by Harrison is arranged so that the
expansions cancel out and its length and thus its period stays constant
over a range of temperatures.
https://en.wikipedia.org/wiki/Gridiron_pendulum
--Jim Harman