In late 1922, he began writing longer works, which were serialized in Adventure. The first ones, featuring a trio of adventurers called McKay,Ryan and Knowlton, and other characters, were "The Pathless Trail" "Tiger River", "The King of No-Man's Land" and "Mountains of Mystery".A later story in the sequence "In the Year 2000" (Adventure 1928) was not published in book form; it is a science-fiction novel with racist overtones.
After returning from the Venezuela trip, many of his stories were set in that environment. He remained a popular writer in Adventure throughout the '20s and '30s. Most of his longer works were republished in hardback. In the '30s, he started appearing more regularly in the adventure pulp Short Stories with stories set in Venezuela.
He was a member of the American Geographical Society
He died in New Hampshire in 1959, the state where he had grown up.
Links: Reviews of the Pathless Trail and Tiger River