LIST OF ILLUSTRATIONS. 



Curve to represent electrical induction . 



Do. do. ... 



Do. do. ... 



Diagram showing the effect of a favoring wind on sound 

 Diagram showing effect of adverse wind on sound 

 Diagram showing the effect of a compound wind on sound 

 Sketch map of Block Island 

 Curve of audition, August 10th, 1875 . 

 Sketch map of Little Gull Island and vicinity 

 Curve of audition, September 2d, 1875 



Do. 

 Do. 

 Do. 

 Do. 

 Do. 



3d, 



4th, 



6th, 



7th, 



8th, 



Paoe. 

 175 



176 

 181 

 449 

 449 

 450 

 459 

 468 

 470 

 475 

 478 

 479 

 480 

 481 

 482 



