534 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



When the gap is relatively narrow the shapes of the curves for direct 

 and reversed currents differ little from those of the corresponding curves 

 when the gap is closed, though the time required after the closing of the 

 circuit for the current to attain (say) 99 per cent of its final value slowly 

 increases with the gap- width. Figures 15, 16, 17 show curves for direct 

 and reversed currents when the width of the air gap was 1.6 mm., 

 6.6 mm., and 28.3 mm. For gaps much wider than the last, the two 

 curves of each diagram fall closely together. When with the same 

 battery a sufficiently large non-inductive resistance was introduced into 

 the circuit to reduce the current to 8.5 amperes, the building-up curves 

 for gaps of width 1.6 mm. (full lines) and 25.0 mm. (broken lines) had 

 the forms shown in Figure 18. 



