The Suns of Caresh - Paul Saint

US screenwriter and author of some sf interest for at least two of his series of adventures for boys: the Mystery Boys series of adventures for boys, all five volumes – including The Mystery Boys and the Inca Gold (1931), a Lost Race tale – being published simultaneously

Contents
The Mystery Boys and the Inca Gold (1931)
The Ghost of Mystery Airport
The Mystery Boys and the Secret of the Golden Sun
The Mystery of the Fifteen Sounds
The Haunted Hangar
The Mystery Boys and Captain Kidd's Message
The Mystery Crash

The Haunted Hangar-
Second entry in series of teen aviation stories, filled with lots of scientific jargon, a jewel heist, and adventure. Van Powell is a pseudonym of early Hollywood screenwriter, Ardon Van Buren Powell

The Mystery Boys and the Inca Gold -
It's a generic boy's adventure novel along the lines of something the Stratemeyer Syndicate might write. Or more accurately the male equivalent of the Mystery of Carlitos, except in Peru instead of Mexico. Really, that's all you need to know.

The Mystery of the 15 Sounds-
When Roger's uncle offered him an opportunity to help in his scientific laboratory while the boy's parents were in Europe, Roger jumped at the chance. His uncle's laboratory—one of the most perfectly equipped—was the most fascinating place in the world.

Even the latest scientific devices, however, could not keep out the "Voice of Doom" which sounded hollowly through the laboratories in the dead of night, or prevent the ghostly antics of the phantom kangaroo and his ape-like companion. These and many other occurrences make THE MYSTERY OF THE 15 SOUNDS one of the best boys' mystery stories of the year.