Spanish merchant ships, called Manila Galleons, made the roundtrip between the Philippine Islands and the ports on the west coast of what is now Mexico, almost every year for the 250-yr period between 1565 and 1815. The log books of these galleons contained weather information which was thought to be of value in the study of the historical climatology of the tropical and midlatitude areas of the Pacific Ocean. A search was made for the log books of the Manila Galleons to determine how many are still extant and the nature of the weather data that they contained. The search was made with the assistance of expert historians and paleographers who were experienced in searching archives where the log books were thought to be on file. The following archives were searched: the Museo Naval in Madrid, Spain; the Archivo General de Simancas in Simancas, Spain; Archivo De Indias in Seville, Spain; Archivo General de la Nación in Mexico City, Mexico; and the National Archives in Manila, The Philippine Islands. Only sixteen log books were on file in the archives in Madrid and Seville. All of the logs that were found were from the period between 1766 and 1808. The inevitable conclusions that were reached were that log books for some of the earlier voyages may never have been written and that most of the log books that were written were either physically lost or were lost due to the ravages of time, moisture, insects or war.

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1A draft of the manuscript of this paper was reviewed by Dr. Harry Kelsey, formerly chief curator of the Natural History Museum of Los Angeles County, California, and now with the Huntington Library, in San Marino, California. In his review, Kelsey stated that “I don't think that historians who specialized in the study of the early Pacific voyages ever believed that there were great masses of logs available” and “I think that at most (during the 15th and 16th centuries) the pilots kept notes on their charts or on scraps of paper, largely for use in revising their charts, but also to record the major events of the voyage in the unlikely event that this might be required later. The few ‘logs’ that exist for the 16th century are just this sort of thing-reports drawn up after the voyage, rather than accounts kept as the voyage progressed.”

Professor Iris Engstand, Head of the Department of History at the University of San Diego, also reviewed this paper. She suggested that a draft of the paper should be sent to Robert F. Marx, a well-known submarine archeologist from Indialantic, Florida. She described him as “ . . .a marine archeologist who located many lost galleons and searched for their logs.” Marx reviewed a draft of this paper. After the review he wrote “I've been searching for the same log books and you found some of the ones I had found and some others as well. I still feel that somewhere in Spain or Mexico more must exist and will continue my search, especially for those of the 16th and 17th centuries.” Marx stated that he had spent a great deal of time searching for log books in the National Archives in the Philippines and agrees that the archives are in very poor condition. He also stated that “I found a great deal on ship losses in a section dealing with agriculture and also in two bundles listed as Revenue Records.” Thus the question may still be open as to whether more Manila Galleon log books are still extant.