404 HAYES— U. S. NAVY MV TYPE OF HYDROPHONE. 



determine the direction of a submerged submarine enables it to 



serve as a powerful aid in safeguarding navigation in times of peace, 



and it is the confident belief of those most familiar with its operation 



that this device is destined to save more vessels and lives than were 



destroyed during the war by the U-boats that brought about its 



development. 



Engineering Experiment Station, 

 U. S. Naval Academy, 

 Annapolis, Md. 



