THE INFLUENCE OF SECONDARY RESISTANCE 93 
the small inductorium than in the larger one, so that 
while there are many sorts of experiments in which the 
investigator using a large coil is justified in disregarding 
secondary resistance, to do so would nearly always be 
unsafe if a small coil were being employed.* 
* The Porter inductorium with which this experiment was per- 
formed is of the old, or student, type. The new form, which is 
constructed in accordance with the Kronecker specifications, is well 
adapted for quantitative work. 
