THE INFLUENCE OF SECONDARY RESISTANCE 91 
four times and Z B greater than Z N nine times. The 
small average percentage difference between the two 
coils, a difference only slightly greater than the probable 
experimental error, coupled with the fact that not all the 
variations are in the same direction, seems to me to 
show that in coils differing no more than these the in- 
fluence of inductorium construction as a special factor 
can be disregarded without serious error. 
An important effect of inductorium construction be- 
comes manifest when coils B and H are compared. The 
average difference between Z B and Z H in twelve experi- 
ments was 1 6 per cent; in four of the twelve cases, more- 
over, the difference exceeded 24 per cent. Analyzing the 
series of experiments with reference to the secondary re- 
sistances it appeared that the high average difference is 
due to large differences in the experiments with high sec- 
ondary resistance. Thus five experiments with second- 
ary resistance above 10,000 ohms show an average differ- 
ence between Z B and Z H of 25.7 per cent, while seven 
experiments with secondary resistances below 10,000 
ohms show an average difference of only 4.5 per cent. 
In all five experiments with high secondary resistance 
Z H was greater than Z B . In the seven experiments with 
low resistance Z H was larger than Z B three times, smaller 
than Z B twice, and equal to it twice. 
This series of experiments shows that in inductoria 
differing even so widely as do coils B and H, inducto- 
