Admiral William S. Benson, Chief of Naval Operations, to Vice Admiral William S. Sims, Commander, United States Naval Forces Operating in European Waters
Follow up Copy
Cablegram Received August 11, 1917
Origin Opnav Serial No. Opnav 139
Via N C B Date No. 15011
Copies to File No.
Action referred to:
Pay Inspector Tobey
Opnav 139 The best listening device developed called C tube is being shipped to the following address period D A S D Admiralty London England period It is good for one mile radius all machinery stopped period extremely simple device period The twelve trawlers under officer whose signal number is 114 and accompanying twelve submarine chasers for the French are equipped with this device 15011
Source Note: Cy, DNA, RG 45, Entry 517B.