Who was the “Einstein” behind COSC standard?

[77T]

So I took a little poetic license with this thread’s title...and chose the reference library as the place to post it. The latter reason to reduce the number of jackwagons who would simply say, “who cares”?

I realize my question is more of a trivial pursuit that resulted from reading a few recent threads elsewhere on TRF. Those threads were aimed at Rolex’s new -2 / +2 goal and warranty work, etc. That really wasn’t the place for a rational discourse of the foundational COSC mark of -4 / +6.

I also realize opinions will vary - so I was looking for a reliable citation in the history books.

Here’s my question for the horological historians...if Einstein is best remembered for E = mc2 then who should we remember as the author of -4 / +6 ?

And maybe more importantly, why is the chronometer certification measure stated as -4 / +6 ? Why not -5 / +5 ? Or almost any other range that equals 10 seconds of variation to be measured over 16 days in different positions and temperature.

I have written to both COSC and ISO (ISO 3159 is the international standard). And I reached Directors at both organizations. Their replies are circular in logic. In other words, COSC states they comply with ISO 3159. ISO states the technical committee set an international standard that expanded a COSC measure beyond Swiss manufacturing.

As for history, COSC predates the ISO working group. And before COSC, there were Swiss Observatories and watch cantons that toiled over different chronometer certification levels. I don’t have any better information to share...but somewhere there is a name, or maybe a group of names, who birthed a standard we simple call -4 / +6...

It’s like John Harrison and his Marine Chronometer - and the pursuit of measuring longitudinal progress upon the open sea in the 18th Century. But for horologist Rupert Gould’s
obsession to revive it in the 20th Century - Harrison’s name might have been lost to modern mariners and horologists.

So who can add any knowledge and facts?




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[77T]

BTW see https://journal.hautehorlogerie.org/...a-chronometer/

A good discussion with COSC...

And this link explains how some watchmakers are going above and beyond: https://www.watchtime.com/wristwatch...quality-marks/


And an excerpt from Worn and Wound:

The standard the COSC developed was stringent, a demanding regimen of tests nearly on par with the grueling Neuchatel trials.

Encompassing 16 consecutive days of testing, the COSC’s method winds and measures the movement once every 24 hours. Over the course of these 16 days, each candidate watch is tested in five different positions and at temperatures ranging from eight degrees Celsius (46.4 degrees Fahrenheit) to 38 degrees Celsius (100.4 degrees Fahrenheit).

During these tests, the watch must remain accurate to within -4/+6 seconds a day on average with a maximum allowed rate variation of seven seconds a day between test days.

Five other criteria are also judged, creating a standard so strict only three percent of annual Swiss watch production (a figure slightly over 1,000,000) qualifies for the chronometer label.

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[Sgt. Henry]

I’m curious to know if the median range of deviation for movements fall within more the +6 range. It would appear that most run fast rather than slow. Was it divised for automatic movements or mechanical?

Years ago I took a celestial navaigation course and became intrigued with the history. I guess it’s a nerd subject but I’m interested