Tidal Investigations on the West Coast of South America

UNTIL recently, tidal information for the west coast of South America was meager and systematic observations were lacking entirely. In a publication issued in I937 a chart picturing the status of tidal investigations in the Pacific Ocean showed no station in operation on the west coast of South America and only one where such observations had been made.' Thanks to a program sponsored by the United States Department of State, this lacuna is now being filled. This program contemplates systematic observations and is noteworthy in that it is a cooperative undertaking on the part of the government of the United States and the governments of the South American countries concerned. The Coast and Geodetic Survey was named as the United States agency for these investigations, and early in I94I, under orders from the Director of the Survey, the writer proceeded to South America and established four tide stations: at Buenaventura, Colombia; Guayaquil, Ecuador; Matarani, Peru; and Valparaiso, Chile. At each of these places some local governmental agency was designated by the government to cooperate in the installation of the station and to continue the observations systematically. At each station a standard automatic tide gauge was set up and five bronze disk bench marks were installed. The tide record is in the form of a continuous curve representing the rise and fall of the tide on a suitably reduced scale, and once a month this record is sent to the Washington office of the Survey for tabulation and analysis. Copies of the tabulations and analyses are then forwarded to the cooperating agencies in South America. Under an extension of this program, four additional stations were established by the writer in the latter part of I94I and early in I942; at Talara and Callao in Peru and at Puerto Montt and Punta Arenas in Chile. The