M. F. Reich on Diamagnetic Action. 253 



rent of from 1 to 4 of DanielFs elements to pass through the 

 spiral. In the circuit a tangent-compass was introduced, and 

 from two tixed points of the circuit a branch current was sent 

 through the multiplier of a sine-compass. The tangent-compass 

 was only divided into single degrees, and admitted therefore of 

 no very accurate measurement of the strength of the current. 

 The sine-compass, constructed by (Ertling of Berlin, is a very per- 

 fect instrument, and permitted of a safe observation of the de- 

 tiection of the needle to single minutes. It was, however, formd 

 that after the circuit was broken the needle did not return exactly 

 to zero, a consequence of the construction which materially in- 

 terferes with the exactitude of the instrument. The observations 

 gave as follows : — 



We have therefore as mean result, — 



Fourth experiment. — In the arrangement nothing was changed, 

 except that the tangent-compass and sine-compass were placed in 

 another room, so as to avoid all attraction of the electro-magnet 

 upon the instruments. M. Fritzschc had the kindness to lend 

 me his assistance in making the observations. We observed as 

 follows : — 



