120 M. F. Kohlrausch on the Determination of the Absolute 



the ratio of whose axes is equal to 1*056, and that the annular 

 space occupied by the wire has a circular section of 36 millims. 

 diameter. 



Hence it follows that the desired surface 



F = 29,7 74,300 square millims. 



(2) The semidiameter of the coils of the tangent- compass, 

 also determined from the length of the coiled wire, is 



r = 401,606 millims. 



(3) To ascertain by means of oscillations the directive force 

 of the wires of the bifilar galvanometer, the moment of inertia 

 of the latter must be known. It was found (determined by 

 Gauss's method) to be 



K = 432331. 10 6 . 



(4) The torsion-coefficient of the cocoon -thread to which the 

 needle of the tangent-compass is suspended, compared with the 

 directive force of the earth's magnetism, was found to be 



% =0002528. 





(5) The distance of one pole of the needle from the axis of 

 rotation can be taken with sufficient accuracy as 



/=20 millims. 



As a specimen of a measurement of intensity and of currert, 

 two successive determinations made on the 23rd of October, 

 1868, are here given. 



The time of oscillation of the solenoid was observed to be : — 



Before the deflections . . =33*8082 seconds. 

 After the deflections . . =33*7963 „ 

 Hence the mean £ = 33*8023 seconds. 



From this is calculated the directive force of the suspending- 

 wires, 



2 



D = K^ =37344. 10 5 . 



The current of a Grove's element (a resistance of three mercury 

 units being inserted) was simultaneously passed through both 

 instruments. A special series of experiments had shown that 

 the directive force of the suspending-wires underwent no change 

 even with a far stronger current. The bifilar galvanometer was 

 deflected 429*78 millims., measured on a scale at a distance 

 of 3960*8 millims. from the mirror; the needle of the tangent- 

 compass 458*57 millims., on a scale at a distance of 3681*6 



