I erred. I knew about K20 and K4 , which the U.S. received in 1890. K20
arrived first as was designated as the official U.S. copy of the
prototype kilogram (IPK). K4 arrived later (still in 1890) and was
designated as a "check standard" to monitor K20.
What I did not know was that the U.S. acquired a third copy in 1996, K79.
See
http://findarticles.com/p/articles/mi_m0IKZ/is_1_106/ai_82777386/
and a later page
http://findarticles.com/p/articles/mi_m0IKZ/is_1_106/ai_82777386/pg_9/
Jim
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James R. Frysinger
632 Stony Point Mountain Road
Doyle, TN 38559-3030
(C) 931.212.0267
(H) 931.657.3107
(F) 931.657.3108
On 2012-01-19 16:46, James Frysinger wrote:
NIST. Both U.S. copies of the one prototype kilogram.
Jim
