During these pioneer experiments with the phonograph among the Zuñi and Hopi he became deeply interested in primitive religion, and for four years was engaged in studies of the ritual of the latter, in the employ of the late Mrs. Mary Hemenway. In order better to appreciate Indian mythology and ritual, he was initiated into the Antelope and Flute priesthoods of the Hopi, from which relationship many secret ceremonies of this tribe were witnessed and described for the first time. The archæology of the Zuñi and Hopi also interested him, and while connected with the Hemenway Southwestern Expedition Dr. Fewkes gathered in Arizona a large collection of Indian objects which is now on exhibition in the Peabody Museum at Cambridge. In 1892-93 Spain held an Historical Exposition at Madrid in commemoration of the fourth centenary of the discovery of America by Columbus. The Hemenway Expedition was requested by the Spanish Government to participate in this celebration, and Dr. Fewkes had charge of the Hemenway exhibit and served on the jury of awards. Up to the year 1894 our knowledge of the Walpi Snake Dance was fragmentary; since that date a large literature on it has accumulated. The account of this startling festival published that year by Dr. Fewkes is recognized as the most exhaustive on the subject that has yet appeared. After the death of Mrs. Hemenway in 1894 the Hemenway Southwestern Expedition was given up and in 1895 Dr. Fewkes was invited to conduct archæological exploration in Arizona for the Smithsonian Institution. He moved to Washington and for several years engaged in field work for that Institution, during which time extensive collections were made of prehistoric pottery and other objects, the more striking specimens of which are now installed in the United States National Museum. The publication of this material marks the beginning of intensive archæological work on southwestern cliff-houses and pueblos. At the close of the Spanish war there was a demand for more scientific literature on Porto Rico and the West Indies, which led to field work in the islands and publication of the Report on the Aborigines of Porto Rico and Neighboring Islands. In 1904 the Smithsonian Institution began an archæological survey of the Gulf coast of Mexico, the results of which appeared in “Antiquities of the Gulf Coast of Mexico.” In the winters of 1906 and 1907 Dr. Fewkes had charge of the excavation and repair of the ruin Casa Grande in southern Arizona, an illustrated report on which was published in the Twenty-eighth Annual Report of the Bureau of American Ethnology. In the summers of 1908 and 1909 he excavated and repaired Spruce-tree House and Cliff Palace, and in 1915 and 1916, Sun Temple and Far View House, all situated on the Mesa Verde National Park, in southwestern Colorado. In 1909 and 1910 he visited large undescribed cliff-houses in the Navaho National Monument, northern Arizona.