PEIRCE. — COKRECTION FOR COUNTER ELECTROMOTIVE FORCE. 1G9 



of short period, when a very sudden impulse from a magneto-inductor 

 was sent through it ; the curve starts very abruptly at 0. Figure 2 is 

 a photographic reduction, on the same scale as that of the other figure, 

 of the record, just as it was removed from the drum, of an excursion 

 of the same galvanometer when a condenser discharge was sent through 

 it. The straight line through K represents the zero position of the 

 coil ; the curve begins at X, but not so abruptly as before. When the 

 paper was on the drum, the points A, B and the points F, G fell to- 

 gether. It will be noticed that the time of the first swing of the coil 

 on one side of its zero is nearly the same, about 2.34 seconds, in both 

 diagrams. 



Thb Jefferson Laboratory, 

 Harvard College, Cambridge, Mass. 



