The Application of the Sixth Sense to Ships 



" The air associated with fog is, as a general rule, highly homo- 

 geneous and favourable to the transmission of sound. The notions 

 hitherto entertained regarding the action of fog are untenable." 



The most unfavourable weather for sound is when the sun 

 is shining brightly and when the air is optically perfectly clear. 

 Under these conditions, we have heated air rising up from the 

 earth, and cooler air descending ; this produces a kind of a 

 glimmer in which it is very difficult to sight a gun at long range 

 with any degree of exactness, but my apparatus would not be 

 needed in this kind of weather. 



It is well known that the air around a large iceberg is 

 extremely cold in fact, so cold that certain scientific men have 

 thought that it might be possible to detect the presence of 

 icebergs by the use of a delicate thermometer ; but the cold 

 air does not extend far enough around the iceberg to make this 

 practical. Cold air, however, lends itself admirably to the use 

 of my apparatus, because the air itself about the iceberg, being 

 of a different density from the surrounding air, acts as a re- 

 flector returning the vibrations to the ship. 



In Professor Tyndall's experiments I find the following : 



" In the experiments at the South Foreland, not only was it 

 proved that the acoustic clouds stopped the sound, but that the 

 sounds which had been refused transmission were sent back by 

 reflection." 



