44 



RESEARCHES ON 



II. 



The means are not very far from those already found, but only a little greater, 

 which, however, must be the case, since the pole cannot be exactly in the middle 

 of the wires. 



After having thus determined the action of the polar diameter, we proceeded to 

 examine that of the other two principal axes. What follows is a table of the 

 intensity of action of the current on the horizontal diameters, which join the 

 middle of the two lunary surfaces covered by the currents, and lying in the mag- 

 netic meridian. 



Table C. 



Position of 

 needle. 



1st series. 



2d. 



3d. 



4th. 



5th. 



General 

 mean. 



Difference between 

 max. and min. 



. centre. 



1.000 



1.000 



1.000 



1.000 



1.000 



1.000 



1.000 



2 tenths. 



1.001 



1.021 



1.015 



1.021 



1.017 



1.017 



0.010 



4 " 



1.035 



1.067 



1.071 



1.071 



1.062 



1.058 



0.036 



6 " 



1.223 



1.142 



1.137 



1.163 



1.136 



1.140 



0.040 



8 " 



1.188 



1.222 



1.222 



1.202 



1.194 



1.205 



0.033 



The rate of increase here is rather slow on account of the spreading of the wires, 

 and the different distances of both poles. To calculate this exactly is very labori- 

 ous, because the action of two circles equally inclined, is also in the case of the 

 experiments not so very far from being equal to their sum collected on the meridian, 

 as in the case of the polar axis. 



Table for the Intensity of Action of the Current on a Diameter perpendicular 

 to the preceding one. 



Table D. 



Position of 

 needle. 



1st series. 



2d. 



3d. 



Means. 



Difference. 



centre. 



1.000 



1.000 



1.000 



1.000 



1.000 



2 tenths. 



0.923 



0.932 



0.972 



0.939 



0.049 



4 " 



0.788 



0.844 



0.830 



0.821 



0.033 



6 " 



0.621 



0.638 



1.683 



0.648 



0.014 



7 " 



0.498 





0.501 



0.499 



0.014 



The rapid diminution of force is due to the shortness of the needle, in conse- 

 quence of which a tenth of the radius of the circle sets both poles out of the circle, 

 and their action becomes contrary. 



Finally, we find the intensity outside the globe in the prolongation of the polar 

 axis, as follows : — 



