above the trackless heart of Africa, how they found the hidden hoard of priceless ivory secreted by slavers in the wonderful Moon Mountains, what strange things came about through their being hunted by the vindictive Arab slave trader, with many other interesting adventures, you can do so by procuring The Boy Aviators in Africa.

Through the coaxing of their warm chum, Billy Barnes, the boys were next induced to enter in a competitive race across the continent, and it can be easily understood that the pages of this book, The Boy Aviators in Record Flight, fairly teem with exciting incidents and thrilling adventures. Crossing the great Western cow country, they met with many difficulties from sand storms to treacherous cowboys and renegade Indians that threatened to end their game voyage. But the same indomitable spirit that had carried Frank and Harry through so many trials allowed them to meet with the glorious success they so richly deserved.

From one series of adventures like this it was easy for the wide-awake young air pilots to engage in others. A story of an old Spanish galleon caught in the grip of that mysterious Sargasso Sea, where the circling tides have held vessels amidst the floating grass for centuries, fascinated them, and they set out to explore the dismal region that has been the graveyard for countless ships. Of course, the lure lay in the fact that a vast treasure was said to be aboard this old galleon; and the hunt for it, together with the opposition caused by a rival expedition, makes great reading for boys who have red blood in their veins. It is all set down in The Boy Aviators’ Treasure Quest, which has been voted one of the best of the entire series.

The Boy Aviators’ Polar Dash was possibly the most remarkable example of Young America’s nerve ever written. How the brothers came to plan the trip to the Antarctic region, and what amazing things happened to them while carrying it out, you will certainly appreciate when you read the book. The object of the expedition was fairly covered, and they came back in safety; but only for the aëroplane the result could never have been attained, which proved how valuable an airship might be amidst the eternal ice of the frozen zones.

In the volume following this, the boys again found themselves caught in a swirl of exciting events. They had become engaged to Doctor Perkins, who was not only a scientific gentleman of note but particularly an aviator bent on startling the world through the agency of a monster seaplane which he had invented. He believed that a voyage across the ocean could easily be made in one of his safe aircraft, which combined many features not as yet in common use among the most advanced aviators. On Brig Island in Casco Bay, within sight of the Maine coast, they erected their factory, and manufactured various types of aëroplanes for the market. So far this wonderful seaplane had not been given to the world, for Doctor Perkins was shrewd enough to first get his patents in all foreign countries in order to protect his interests. In The Boy Aviators’ Flight for a Fortune have been related a series of remarkable adventures that befell the young air pilots when trying out the first of these enormous hydro-aëroplanes, that would skim along the water or sail through the air with equal swiftness and safety.

One of these enormous seaplanes had been boxed in sections and shipped over to France, with the design of giving the Government officials an actual exhibition before they would agree to making a large contract with the firm.

Then the terrible world war had broken out, and for some months it was not known just what had become of the precious machine.

Finally word was received that it