1902.] 



the Question of Blaze Currents. 



213 



it had broken, or made, the primary circuit. The distance between 

 this contact and one in the primary circuit was of course so chosen 

 that the induction current itself should produce no effect in the 

 measuring instrument. As the sudden letting in of a resting 

 current would have caused great disturbances in the measuring instru- 

 ment when the short-circuit was broken, it was necessary to com- 

 pensate this very carefully beforehand. By means of the key Ko the 

 compensation could be tested immediately before letting go the 

 myograph. The myograph-stand itself was placed in an adjoining 

 room in order that the movement of its steel rod might not affect the 

 galvanometer. It could however be set in motion from the table on 



which the rest of the apparatus was placed. The secondary coil could 

 be short-circuited by the key K 3 ; the measuring instrument by the 

 key Kj, the keys K 5 and K G allowing of the introduction of either galva- 

 nometer or capillary electrometer to serve as such, in order that the 

 results obtained with the one instrument might be quickly checked by 

 the other. Although the arrangement was well adapted for concordant 

 observations, it was defective, not only in the absence of the apparatus 

 for recording the movements of the electrometer, but also in another 

 more important respect. The necessity of distinguishing what is due 

 to polarisation in the study of "blaze currents" has already been 

 pointed out. With this in view observations ought to be made in 

 such a way as to eliminate the effects of polarisation as much as 

 possible, as would be accomplished by using, to produce a single exci- 



