# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: what is a second?
From: Bill B
Date: 2006 May 9, 22:50 -0500

Good question as to whom invented the whole system. As a start, visit

http://en.wikipedia.org/wiki/Sexagesimal

"The sexagesimal (base-sixty) is a numeral system with sixty as the base. It
originated with the ancient Sumerians in the 2000s BC, and was transmitted
to the Babylonians."

Bill

> I ask this question of the list, after having looking into time divisions 24
> hour day, 60 minute hour and 60 second minute but how the second was defined
> eludes me.   I have seen that a pendulum of 1 meter length has a period of a
> second so if that is how the second was defined I am ok with it.
> Still I wonder if the definition of the second might have preceded the metric
> system defintions?
>
> The problem as I see it is that  to have a clock of accuracy in the seconds,
> before electricity, quartz, and atomic, there had to be some way to decide how
> long a second should be.  Also there had to be some way to set ones instrument
> or clock so that the second reflect the divisions of the day with some
> reasonable accuracy.    I  dont have a problem with  variations in  the rate
> of  a clock  since that is easily compensated.
>
> Longitude being the measurement affected particularly by variations in the
> length of the second and the number from uct.
>
> So to recap, when was the second defined and when was it possible to create
> instruments that could count off seconds accurately?

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