The Secret of Tibet, by William Dixon Bell

A rollicking tale of the Hope brothers as they travel across the hidden mountains of Tibet. The twins ardent aviators in the twenties the time of the great depression encounter disappointment as they receive news that no prizes are being offered for a round the world flight. The twins Dave and Will decide that no prizes are necessary for them to complete their dream. They live out their dream and this leads them into an adventure that takes them across China and Tibet.