"Tom Swift and His Atomic Earth Blaster" The New Adventures of Tom Swift Jr. by Victor Appleton II

Tom Swift Jr. invents a powerful atomic drill that can bore deep into the earth. But enemy agents want it too, and Tom and Bud Barclay are soon fighting sabotage far below the surface. This is Book 5 of the 1954 series, and the hardcover is in good vintage condition at Dead Tree Dreams.