212 A, M. Mayer—Researches in Hlectro-Magnetism. 
action had no influence on the intensity of the megneliaing 
effect. Iam therefore of the opinion that the increased effec 
of the helix was due to superior insulation. 
Ex. e combination of 50 spirals was separated into 
two, each containing 25 spirals. Between the spirals of one 
combination were introduced the 25 spirals of the other, so that 
the current is now passed through one of the combinations and 
the two terminal wires of the other combination joined, Faraday 
has shown, that the “extra-current” in the first combination is 
P 
conclusively showin g that an a combination of spirals or ina 
lia the inductive action of the wire on itself or of 2p Billed 2 
or turns on each other has no effect on the power of thet nett 
zation and therefore no effect on the intensity of the eShiatie oe 
ae them. 
not remember ever having seen a solution of this ques- 
tion, sie these experiments have given it under conditions of a 
very strong inductive action, and with a very delicate apparatus 
for detecting any effect which might have been produced. e€ 
result is one which has an important theoretic bearing on dy- 
namical inductive action, au I reserve for another communi- 
cation my views on that point 
In bringing this research to a conclusion I think I ma safely 
say that these results and experiments have shown the delicacy 
and precision of this method of comparing and measuring the 
electro-magnetic forces; and at a future time I propose using it 
to solve the problems which relate to the variation of the geen 
sities of cores with their diameters and with their surfaces 
to examine the varying magnetizing effects of helices of different 
, diameters, and number of turns of wire, and traversed 
by ¢ currents of cies intensities. 
of the above ar Bee yg As which relate to the inverse 
polarity given ‘ cores placed inside of taagnetiz d 
wires placed outside of helices, are very estive as to an €X- 
lanation of diamagnetism, but I reserve for the present the 
ypothetical notions which ‘they have originated in reference to 
those phenomena. 
South Bethlehem, Pa., June 2,1870. 
