374 Miss Pearson, Note on an Attempt to Detect a Difference, etc. 



per minute whether the magnetic field was off or on. Such a 

 deflection was found to be produced if, in the conditions of the 

 experiment, 5'5 °j^ more of one ion than the other reached the 

 Faraday Cylinder. Although an exact limit cannot be set, it is 

 certain that a readjustment of ions sufficient to change the rate of 

 deflection of the needle by "5 scale divisions could not have escaped 

 detection. The magnetic field used cannot therefore have pre- 



5'5 °/^ ions of either sign from 



escaping beyond it to the cylinder. The magnetic field employed 

 was found to be about 6000 gauss at its maximum, and its greatest 

 rate of variation was 5000 gauss per centimetre. 



vented more than '8 



= 3^"^ 



