272 TABLE 305. 



VARIOUS DETERMINATIONS OF THE VALUE OF THE OHM. 



The legal value of the ohm is the resistance of a column of mercury of uniform cross-section, 

 weighing 14.4521 gms., and having a length of 106.30 cms. This is known as the international 

 ohm. Mercury ohms conforming to these specifications have been prepared in recent years at 

 the Physikalisch-Technische Reichsanstalt, the National Physical Laboratory, and the Bureau of 

 Standards. The wire standards of resistance at the above-named laboratories agree in value to 

 within two parts in 100000. Hence there is a very close agreement in the values of precision 

 resistances calibrated at these laboratories. 



SMITHSONIAN TABLES. 



