KENNELLY. — BUILDING UP VOLTAGE AND CURRENT. 



709 



stands vertical. The shutter must be geared with the shaft 0', so as 

 to move uniformly and uncover one complete turn of the spiral in the 

 interval of one complete rotation of the shaft. The shadow of any pin 

 P on a horizontal plane at /> beneath would then indicate the wave 

 motion at that point from the moment of the wave's first reaching it 



^UilliiitUJj>' 



Figure 4. — Diagram of model for exhibiting the propagation of the first 

 outgoing wave-train along a uniform line. 



until reflected waves disturbed the distribution. The spiral of pins 

 thus constructed would just fit into the arrangement of Figure 2, con- 

 sidered as a hollow cylinder or logarithmic trumpet of revolution. 



In the case of an indefinitely long circuit, as above outlined, the 

 initial current strength at the sending end A would remain the final 

 steady current strength. In other words, there would be nothing to 

 disturb the original simple harmonic voltage and current. At the 

 origin A we should always have : 



or 



also 



or 



E = Ea sin (Jit 



V2 



instantaneous volts (30) 

 effective volts (31) 



E, 



*o 



/„ = /o^ sin wt =■ — sin mt instantaneous amperes (32) 

 Jo 



A 



a/2 



effective amperes (33) 



