[time-nuts] Standards for units
Dr Bruce Griffiths
bruce.griffiths at xtra.co.nz
Tue Apr 3 05:16:46 EDT 2007
James Cloos wrote:
>>>>>> "David" == David Dameron <ddameron at earthlink.net> writes:
> David> (I was taught that 1 meter was 39.37 inches, to define the
> David> inch, but now I see more of 1 inch = 2.54 cm, as someone just
> David> referred to.)
> That was the old inch. It was changed back around 1954 or so. They
> decided they didn't want to have an SI unit looking like it was
> defined in terms of a legacy unit, and so changed from 1 meter = 39.37
> inches to 1 inch = .0254 meters so that the inch was defined in terms
> of the meter.
> Or, as likely, from 1 meter = 3937/1200 feet to 1 foot = .3048 meters.
> The old length is still used for so called survey feet in the US.
> Many conversion routines -- including unix's units(1) and HP's line of
> RPL calculators -- call them US feet.
The change occurred in July 1959.
At which time the UK, USA, NewZealand etc officially adopted the new
definition of the inch.
Canada had adopted it somewhat before this.
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