"The tale of a trip to the frozen North with a degree of reality that is most convincing." or, The Strange Cruise Of The Submarine Wonder
"The vessel moves from the coast of Maine to the boiling sea of the South Pole, and during the trip the voyagers visit the bottom of the ocean--the graveyard of many ships--and have numerous stirring encounters with deep-sea monsters." or, The Mystery Of The Center Of The Earth
"A craft is built which will sail in the air and under the water, and in this the adventurers descend to the interior of our globe by means of a hole found on an island in the ocean."
or, The Most Wonderful trip On Record
"A thrilling tale of a visit to the planet Mars. The adventurers meet with many happenings out of the ordinary. The volume reads like the record of a real trip." or, In Quest Of The Field Of Diamonds
"In a like manner to their visit to Mars, the heroes visit the Moon. They search for a field of diamonds and find the moon to be a land of desolations and silence. They almost perish from cold and hunger. A startling romance that will hold and charm very reader." or, Captives Of The Great Earthquake
"After a tremendous convulsion of nature the adventurers find themselves captives on a vast 'island in the air.'"
or, Captured By Red Dwarfs
"The City Beyond The Clouds is a weird place, full of surprises, and the impish Red Dwarfs caused no end of trouble. There is a fierce battle in the woods and in the midst of this a volcanic eruption sends the Americans sailing away in a feverish endeavor to save their lives." or, Captives Of A Strange People
"Our heroes are captured by strange inhabitants of the inside world and have a series of adventures as wonderful as they are absorbing." or, Exploring The Ringed Planet
"After a rocket ship race to Saturn, two boys have harrowing adventures with snakes at the Boiling Lake in this Land of Vapors."
One of the first products of the Stratemeyer Syndicate and its earliest venture into science fiction.
This series is somewhat of an oddity due to the huge time gaps that occurred between the release of volumes 6 & 7 and volumes 8 & 9.
All volumes originally published by Cupples & Leon.
In the late 30's or early 40's, Whitman Publishing Company reprinted volumes 3, 4, 5, 6, 8 and 9. New dustjackets were designed and the illustrated bindings were eliminated as were the internal illustrations.
In the mid-30's, Cupples & Leon released a 4-in-1 book, Mystery and Adventure Stories for Boys, containing the first story of this series along with Billy Smith - Exploring Ace, The Boy Ranchers & Baseball Joe Of The Silver Stars.