The Radio Boys at Mountain Pass: or, The Midnight Call for Assistance

Ralph, the Train Dispatcher: or, The Mystery of the Pay Car

Fenn Masterson's Discovery: or, The Darewell Chums on a Cruise

The Radio Boys at Ocean Point: or, The Message that Saved the Ship

Ralph on the Engine: or, The Young Fireman of the Limited Mail

Tom Fairfield's Hunting Trip: or, Lost in the Wilderness

Tom Fairfield in Camp: or, The Secret of the Old Mill