PEIRCE. — MANNER OP GROWTH OP A CURRENT. 



527 



suddenly deflected to the end of its scale, but this fact did not affect 

 records of the kind used here. This instrument consisted merely of a 

 mirror galvanometer in which the extremely minute magnet and mirror 

 were fastened to a piece of fine stretched gimp damped in oil. I had 

 four drums for carrying the sensitized paper, or the film when this had 

 to be used, and any one of these could be driven very uniformly at almost 



Figure 10. 



any rate up to a rim velocity of a meter per second by means of chrono- 

 graph clock-work. Most of the paper used was in strips from 16 to 20 

 centimeters wide and some of the curves are about a meter long. The 

 deflections of each oscillograph were strictly proportional to the current 

 in its coil. A large zinc template, which carefully kept the irregularities 

 of the record, was made for each curve ; this template was used in draw- 

 ing a large diagram and the figures here given are copies of these dia- 

 grams very much reduced. A few of the larger records were redrawn 



