92 THE POPULAR SCIENCE MONTHLY. 



face, wliicli were conveyed from the water "by a cylindrical tube 

 of tin some nine feet long and six inches in diameter, one end of 

 which terminated in an orifice for insertion in the ear, and the 

 other was spread out somewhat in the form of a spoon, its open- 

 ing being closed by a flat, elliptic plate of tin, about two square 

 feet in area. By attaching a suitable weight to the lower end of 

 the tube it was easily retained in a vertical position with about 

 four fifths of its length submerged, its flat plate being turned 

 toward the boat carrying the bell. With this simple apparatus, 

 CoUadon was able to hear with perfect distinctness the blows of 

 the hammer on the bell across the widest part of Lake Geneva, 

 when the calculated distance between the two boats was not less 

 than eight miles. 



The sounds heard by Colladon appeared as if they had been 

 caused " by some metallic body striking the bottom of the tube," 

 and they were " as distinct and brief at 13,000 metres as at 100 

 metres from the bell." One set of observations were made dur- 

 ing a strong wind : " The lake, which was at first calm, became 

 violently agitated, and it was necessary to keep the boat in posi- 

 tion by means of several anchors ; yet, in spite of the noise of 

 the waves which struck the tube, he took other observations 

 with the same accuracy as when the air and water were still. 

 And he states, "I am convinced that by employing a bigger 

 bell, and improving or enlarging the hearing apparatus, easy 

 communication could be effected under the water of a lake or of 

 the sea up to fifteen or twenty leagues." 



In February, 1883, Prof. Lucien I. Blake,* now of the Uni- 

 versity of Kansas, but then in Berlin, while investigating the 

 experiments of Colladon and also of Sturm, as to the velocity 

 of sound through the waters of Lake Geneva, thought of mak- 

 ing a practical use of water as a means of communication be- 

 tween vessels at sea. He then devised several methods, assisted 

 by Dr. Konig, of the Physical Laboratory at the Royal Univer- 

 sity, which he tried on his return to this country, and he has 

 been experimenting in that direction from time to time since 

 that date, as opportunity served. 



His plan, in brief, was as follows : A sound-producing appara- 

 tus was to be attached to each vessel, and to be worked under the 

 surface of the water. In times of fog or at night a code of sig- 

 nals would be produced by it which would be transmitted in all 

 directions through the water, with a velocity four to five times 

 that in the air. Each vessel, in addition to the sound-producing 

 apparatus, would be provided with a sound-receiving apparatus, 



* Prof. Blake read a paper on this subject before the American Association for 

 the Advancement of Science, at the meeting in New York, in August, 1887, from which, 

 with his kind permission, this abstract has been made. 



