in 1906 In 1904, Slevin was hired by the Academy of Sciences and trained by
John Van Denburgh as a scientific collector. In June 1905 the academy embarked upon a 17-month research expedition to the
Galápagos Islands and other Pacific islands with a crew of eight scientists led by
Rollo H. Beck; Slevin was in charge of reptiles. The purpose of the voyage was to study the geology of the islands as well as collect plants, mollusks, insects, birds, mammals, and reptiles, and, as Van Denburgh wrote, "to spare no effort to secure specimens or remains of those races of the
gigantic land tortoises which long had been thought extinct." Slevin, aided by 18-year-old assistant herpetologist Ernest Samuel King, took detailed notes on the biology of the animals he collected. Biologists Thomas and Patricia Fritts, who later edited and published Slevin's field notes, write that although he was "first and foremost a collector of reptiles, he was also a conscientious naturalist who recorded observations in a manner uncharacteristic of the times." During the expedition, the academy was nearly destroyed by the
1906 San Francisco earthquake and subsequent fires, and the collection of reptiles and amphibians was reduced from over 8,000 specimens to only 13. After a full year of exploring the islands, the expedition left the archipelago on September 25, 1906, and returned to San Francisco on November 29 of that year. Slevin, King, and others had collected over 4,500 reptiles–nearly 4,000 from the Galápagos alone–which Van Denburgh called "by far the largest and most important collections ever gathered on these islands." In addition to his field observations, Slevin published the ship's logbook, which is of historic value to students of the Galápagos. Slevin returned to the Galápagos Islands to collect again in 1928–1929. ==Other work==