The Operation and Use of the Apparatus 



miles per hour, and travelling towards us slightly to our 

 starboard. Our next blast shows us that the ship is only a 

 mile distant, and very much to the starboard ; we follow 

 her direction, and when she is in a position to present her 

 broadside to us we find in sending out a blast that the echo is 

 very strong, the bells at the receiver ring violently, and the 

 recorder makes a large and distinct marking on the paper 

 strip. The weather has been so thick that we have not 

 seen the ship, but we have a fair idea of her ; we know 

 her speed and the direction in which she is sailing. 



The next day is fine and clear ; we meet several ships and 

 send out blasts and note the readings. Amongst these ships 

 is a large fully rigged sailing ship with all sail on. When 

 she is off our beam, we turn our indicator and recorder in 

 her direction and send out a strong blast of two seconds' 

 duration ; this is followed in six seconds by a ringing of all 

 our bells, and the recorder has a clear record showing that 

 the object sending back the waves or vibrations is of great 

 size and high out of the water. 



We are now off the New England coast ; night is coming 

 on and there is a slight mist, so that a ship's lights cannot 

 be seen more than half a mile distant. Suddenly the two 

 smaller bells at our indicator ring violently ; we have not 

 sent out a blast, and so we know it is the blast from another 

 ship's vibrator. We answer by a blast and then liberate the 

 clockwork, so that the paper strip is fed out continuously, 

 and very soon our recorder shows the letters A B C to be 

 followed by a message and a reply. The ships are now 30 

 miles apart, and we find that the primary blast will work 

 our recorder at that distance, or more than twice as far 



