500 



WEBER ON THE MEASUREMENT 



moreover be rendered complete by the case, in which the centre 

 of the two coils coincided. 



Simultaneously with the observations made on the dynamo- 

 meter, the intensity of the current which was transmitted through 

 the two coils of the dynamometer was measured by another ob- 

 server with a galvanometer. By these auxiliary observations I 

 was enabled to reduce all the observations made on the dyna- 

 mometer in accordance with the law shown above, (that the elec- 

 tro-dynamic force is in proportion to the square of the intensity 

 of the current,) to an equal intensity of the current, and thus to 

 render the results obtained comparable. 



The following table gives the reduced mean values which were 

 obtained in the different instances. The first vertical column 

 shows the distance of the two coils of the dynamometer; 

 above the other columns, the direction foi'med by the line uniting 

 the two centres with the axis of the bifilarly-suspended coil 

 directed towards the magnetic meridian is given : — 



It is at once seen that when the centres of the two coils of the 

 dynamometer coincide, or their distance apart is = 0, the dif- 

 ference dependent upon the change of the direction in which the 

 multiplier is removed from the bifilarly-suspended coil, va- 

 nishes. The result obtained in this case therefore could only 

 be repeated in the above table in the various columns. 



Moreover, the above table shows that the results obtained for 

 an equal distance in opposite directions varying 180°, agree 

 together as far as the observations could be depended upon. 



These values, when reduced by taking their means, after con- 

 verting the divisions of the scale into degrees, minutes and 

 seconds, yield the following table : — 



