HYDROGRAPHIC OFFICE PUBLICATIONS.—To those mariners who contribute marine data relating to this or other publications of the Hydrographic Office, the Pilot Charts, Notice to Mariners, and Hydrographic Bulletins are given in exchange free of cost. In American ports in which a Branch Hydrographic Office is established mariners of every nationality should call for them in person and receive in addition the latest information regarding charts, sailing directions, dangers to navigation, etc. All services free. Office hours 9 a.m. to 4.30 p.m. To other American ports and to foreign ports the Pilot Charts will be forwarded by mail upon application to the Hydrographic Office or to the nearest Branch Hydrographic Office. In such cases state clearly for which ocean and for which months they are desired and the post-office address to which they should be sent. OTHER PLACES OF SUPPLY.—The above-named publications and observers’ blanks will also be furnished upon application to the Harbor-master at Manila and the American Consular Offices in the leading seaports abroad. MARINE DATA REPORTS.—These should be handed or mailed promptly upon arrival in port to the nearest Branch Hydrographic Office, or to the Main Office, in the franked envelope supplied for that purpose. At places outside of the United States or its possessions such communications may be handed to the American Consul who will mail them free of cost. OBSERVER’S ADDRESS.—Mail for captains and officers of the merchant marine is frequently returned because the ship has sailed from the port named in the address. Those who desire their Pilot Charts, Notices to Mariners, and Hydrographic Bulletins to reach them regularly should make arrangements to have their mail follow them, or else give the Hydrographic Office an address at which such mail will be held for them until they return. =13.= LAG IN U.S. NAVAL RADIO TIME SIGNALS The U. S. Naval observatory during the year 1925, determined the lag of the Annapolis and Arlington signals to be about nine hundredths of a second (.09). The error of the time signal is generally less than one-tenth of a second (.1). =14.= FOG. The dotted blue lines show the percentage of days on which fog was observed in November from 1901 to 1906, inclusive. =15.= HYDROGRAPHIC OFFICE PUBLICATIONS OBTAINABLE AT THE PANAMA CANAL