A Sixth Sense 



The energy employed by the bat is certainly not more 

 than one - thousandth part of a horse-power, but it serves 

 the bat's purpose perfectly well. 



Suppose, now, that we construct an apparatus that will 

 produce atmospheric vibrations of about the same frequency 

 as those produced by the bat, but instead of using the 

 infinitesimal amount of energy employed by the bat, we 

 use two or three hundred horse-power that is, we send out 

 waves that have an amplitude and energy at least three hundred 

 thousand times as great as those sent out by the bat. These 

 vibrations, although of great energy, will not be audible to 

 our ears, but they will shake up and agitate light objects 

 for a considerable distance, and will travel at least twenty 

 miles, so that they could be received and recorded by a 

 suitable apparatus at that distance, and would be able to 

 travel at least five miles and send back to the ship a reflected 

 echo that would be strong enough to be detected. 



The quantity of steam required would not be very great, 

 because the valve would not be opened very often, and 

 when open w r ould not remain open more than a second at 

 a time ; therefore, the total amount of steam required while 

 signalling was actually going on would certainly not exceed 

 ten horse-power. 



The apparatus could also be used for communicating with 

 other ships by giving off long and short blasts representing 

 the dots and dashes of the Morse system. 



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