DEVELOPMENT OF THE TELEPHONE 



the efficiency of the instrument over those in which the 

 vibrations of the voice-impulses are sent forth. The 

 scientific explanation of why such an arrangement is 

 more efficient, is so complicated as to mean little to 

 the average layman. A recent writer explains it by 

 metaphor as follows: 



"Imagine a man standing on the bank of a small 

 pond, throwing bricks into the water. These create 

 big waves at broken intervals which can be managed 

 to convey signals of a code. That is the old spark of 

 telegraphy. 



"Now, instead of a man with bricks, picture a huge 

 funnel containing sand, which allows one grain at a 

 time to fall to the water at a high rate of speed. The 

 waves sent forth are barely perceptible, but are none 

 the less existent. Each time the man wants to send a 

 signal or impulse he shuts off the flow of sand. He can 

 do this with infinitely greater speed than the man can 

 throw bricks. Hence it follows that the number of 

 waves or impulses transmitted in a given time is only 

 limited by the grains of sand that can be dropped. Re- 

 sults are convincing. Under the old system about forty 

 words a minute could be transmitted. Under the new, 

 40,000 words an hour are possible, could they be sent 

 so rapidly." 1 



The infinite advantage of wireless over wire tele- 

 phones has been demonstrated recently on many oc- 

 casions. Storms and accidents of all kinds are forever 

 putting connecting wires out of commission, completely 

 isolating whole regions for hours or even days at a time. 

 Even submarine cables have the advantage over ordi- 



