Rockwood Roy

Dismantling the dirigible-ship Monarch & the submarine Porpoise, our crew constructs from the combined parts the Flying Mermaid which is both airship & submarine. They leave their home in Maine & head for a region of the South Polar sea where they previously found an opening into the Hollow Earth & fly right in. Deep below the earth they discover a lost race of giants & experience a tremendous lot of adventures involving a murderous plant, weird animals, & a subterranean temple of treasure. Using parts taken from the dirigible-ship Monarch and the submarine Dolphin our crew constructs the Flying Mermaid, an airship-submarine! They take their new vehicle to the South Polar sea and discover an entrance in the Hollow Earth, where they find a lost race of giants, murderous plants, weird animals, and a temple full of treasure...

After learning of a diamond field on the Moon, our crew heads for the satellite, where they discover a petrified city populated by petrified people.

Jack and Mark build an airship and head North, hoping to find a rare plant that grows only in Alaska. But a freak earthquake causes a chunk of the Earth, along with our protagonists, to fly into outer space.

The adventuresome crew builds a submersible craft, the Dolphin, that runs on sea water and chemicals. On the maiden voyage they battle sea monsters, pass through a sunken graveyard, and discover an opening that leads to the center of the Earth!

Mark and Jack enroll in the Universal Electrical & Chemical College, and meet the inventor Santell Roumann. Santell has discovered a new fuel source called Etherium, and together the group builds a rocket ship and travel to Mars.

Orphans Mark and Jack are fostered by Professor Henderson, with help from the professor's assistant Washington White and his friend Andy Sudds, the big game hunter. In their first adventures the Professor builds a unique boat/dirigible called the Monarch, which they use to visit the North Pole.