"The Pony Rider Boys in the Grand Canyon; Or, The Mystery of Bright Angel Gulch" is a juvenile adventure novel written by Frank Gee Patchin. This book is part of the "Pony Rider Boys" series, a series of adventure stories for young readers.The "Pony Rider Boys" series follows the adventures of a group of boys who embark on various journeys, exploring different regions of the United States. In this particular installment, the boys find themselves in the Grand Canyon, and the storyline likely involves mysteries, challenges, and exciting encounters as they explore the natural wonder.Frank Gee Patchin was a prolific writer of juvenile fiction in the early 20th century, and the "Pony Rider Boys" series was among his popular works. These stories typically combine elements of outdoor adventure, friendship, and a sense of exploration.