Pat Naughtin wrote in USMA 25917:
Emu
Emu meaning English mixture of units has the same problems as English units
and Ye Olde English Mixture of units.
emu stands for Electromagnetic Units. They include
abfarad = 1 GF
abcoulomb = 10 C
abampere = 10 A
abvolt = 10 nV
abhenry = 1 nH
abohm = 1 1 n�
These are centimetre-gram-second units. The international electrical
units are metre-kilogram-second units. The electrostatic units are
also centimetre-gram-second units and are connected to the emu units
by conversioin factors of c or c^2, where c is the velocity of light.
the inch, the foot, and the yard did not have standard
lengths until 1959; and even then they were only standardised for English
speaking nations. The pouce, or French inch, still has no definition.
The British yard was measured and found to be 0.914399 m,
or . 1 British inch = 25.399956 mm.
The American yard was defined (in 1893?) as 3600/3937 m. This gives
1 US inch = 25.400 050 8 mm.
By an international conference in 1959 the inch was redefined as 25.4
mm. This value was used by Canada since 1951 and by ISO and probably
by ISA before that.
Talleyrand in 1790 in proposing that a new system of measures be
developed, listed 13 different values of the pied in use in various
regions of France. The Paris pied or the pied du Roi was 324.8 mm.
This value is legal in Quebec. Any legal document there that mentions
the foot of 304.8 mm must describe it as "mesure anglaise".
--
Joseph B. Reid
17 Glebe Road West
Toronto M5P 1C8 Telephone 416-486-6071
