#11 in the Tom Swift Jr. series. Grosset and Dunlap hardcover publication. Copyright 1958. Printed around 1958. Internal book list and rear jacket flap both list to #13 Space Solartron (1958), so this book is a very early, maybe 2nd or 3rd, printing. Author "Victor Appleton II." Victor Appleton the first was the Stratemeyer Syndicate pen name for the initial Tom Swift series. Very good, clean, square blue tweed book. Sturdy spine and hinges. Blue and white space lab endpapers. "100100" designation on upper right corner of dust jacket front flap. No writing/markings. Good page blocks. Very nice wrap-around dust jacket with minimal small closed-tear damage at bottom edge, slight jacket wear at spine top and bottom. In this one, Tom develops inventions based on his repelatron principles, dealing with the selective matter repelling - which in this case can be used to repel seawater for easier transportation. He discovers helium at the sea floor, and is able to harness it. A mysterious submarine and the discovery of a booby-trapped pirate treasure add to the adventures. Note to New York state residents: an 8.75% sales tax is applicable. (TSB11)