Dear Frank,
You're right - the timeline casts doubt on the premise of the enquiry.
Well spotted!
For anyone who's interested, here's a snippet from/Enclopaedia
Britannica/ (7th ed.)
"The first [Equation Clock] was made about the year 1693 by Mr Joseph
Williamson, an English artist then working for Mr Daniel Quare
watchmaker in London, who sold it to go to Charles II King of Spain
about the year 1699. It went 400 days with one winding and had two fixed
and two movable circles for the hands to mark the time on : the former
giving the hours and minutes of mean time; and the latter, which were
concentric with the former, apparent time. [...] Father Alexandre, a
Benedictine, had laid a project of this sort before the Academy of
Sciences in 1698 which is mentioned in their Memoirs for 1725 but
nothing of the kind seems to have been practised in France till a clock,
the equation work of which scarcely differed from Williamson's, was made
by Lebon in 1717. This was soon after followed by another by Leroy."
I found a 1737 publication /Regle artificielle du temps /by Henry Sully,
an English clockmaker in Paris and clockmaker to the Duc D'Orleans,
which has fairly extensive instructions on how to regulate clocks using
either a sundial or by observing transits of stars, and how to convert
a mean time reading to solar time by use of Equation of Time tables. I
didn't notice any mention of equation clocks when I looked through
Sully's treatise, so I assume they remained rather rare even 20 years
after Le Bon and Le Roy had introduced them.
Thanks to everyone who has responded to my enquiries.
Steve
On 2017-04-26 5:44 AM, Frank King wrote:
Dear Steve,
I have read the replies to your enquiry and I
am not yet convinced by the responses to either
Part 1 or Part 2!
I'll restrict myself to Part 1, where it is
asserted...
...that Louis XIV issued some kind of edict
that all clocks manufactured in France were
to be Equation Clocks (that is, clocks that
showed solar time through a mechanical
Equation of Time 'reversal' adjustment).
One point of note is that Louis XIV reigned
from 1643 to 1715 so this edict must have been
sometime in those 72 years.
Roderick Wall's reference...
https://books.google.com.au/books?id=d1oUAAAAQAAJ&pg=PA462&lpg=PA462&dq=all+clo
cks+manufactured+in+France+were+to+be+Equation+Clocks&source=bl&ots=ih4yWalJ9E&
sig=6u-sTxpfyTqZNPxRjfbAn7Q_ECk&hl=en&sa=X&ved=0ahUKEwjW9oruqrbTAhVEGJQKHU-NDrs
Q6AEIIzAD#v=onepage&q=all%20clocks%20manufactured%20in%20France%20were%20to%20b
e%20Equation%20Clocks&f=false
says on page 462...
Equation clocks were first made in France,
about the year 1717, by Le Bon and Le Roy.
It seems unlikely that Louis XIV could have
insisted on something that didn't exist in
his time.
As king, Louis XIV no doubt had up-market
clocks in his palaces and he could simply
have instructed his clock-keepers to set
the clocks using a convenient sundial.
The solar day typically differs from 24 modern
hours by a small fraction of a minute and it
is unlikely that the clocks early in his reign
kept time to anything like that precision.
Frequent setting to sundial time would have
been required.
When he upgraded to pendulum clocks he may
have noticed that his clock-keepers had
changed their procedures...
I think the first EoT tables used for
"correcting" clocks were published by
Huygens in 1665 and better tables were
published by Flamsteed about 7 years
later.
Enthusiastic clock-keepers may have used
these tables and the king may not have
approved. The only edict that he need
have issued would have been of the form:
"Do not use the equation of time when
setting the clocks."
I know how to dig out ancient English Acts
of Parliament but I do not know how to find
old French edicts.
Please can someone nail down this edict?
Until I can read this edict in 17th century
French, I shall deem this to be another
example of a much-repeated falsehood
gaining widespread acceptance.
Now to ponder part 2!
Frank
Frank H. King
Cambridge, U.K.
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