[Test-Equipment] OLD lab instrumentation

[Dale H. Cook]

At 07:34 PM 5/30/2004, Brian Clarke wrote:

>Just because millions of people poured their non-biodegradable dish- and
>clothes-washing water into the River Thames in England for many years,
>aided and abetted by the soap manufacturing companies, and killed all the
>aquatic life in the Thames for 30 years or so, doesn't make it right.

No, but the reasons why that was done have nothing to do with the 
principles upon which were based the electrical reference standards of the 
first half of the twentieth century.

For those who would appreciate further information on standard cells (the 
reference standard at NBS was a bank of 40 saturated cells), see W. J. 
Hamer, "Standard Cells, Their Construction, Maintenance, and 
Characteristics" (National Bureau of Standards Monograph 84, January, 1965).

For a brief discussion of saturated and unsaturated cells in a more readily 
available source, see Arthur W. Smith, "Electrical Measurements in Theory 
and Application" (New York: McGraw-Hill, 1934), pp. 137-140.

Note that the standard cells we are used to seeing are unsaturated cells. 
The reference standard at NBS used saturated cells. Those must be 
maintained more carefully than unsaturated cells, but are more accurate. 
Independently manufactured Weston normal saturated cells are accurate to 
better than .01 percent of their theoretical value.

Dale H. Cook, Chief Engineer, WWWR Roanoke VA, WCQV Moneta VA, WKBA WZZI 
Vinton VA, WKPA WLNI WZZU Lynchburg VA, WMNA/WMNA-FM Gretna VA
http://members.cox.net/dalehcook/starcity.shtml