TOM SWIFT AND his GIANT CANNON

Alec Petersen is tryin g to convince Mr Swift, Tom's father, to finance an exhibition to locate a hiddenn opal mine. Tom, flying one of his airships, gets tangled up in power lines and is rescued by Mr Petersen. In gratitude, Tom Swift offers to finance the expedition. Meanwhile, Tom is busy inventing a giant cannon, which he hopes to sell to the United States government for use in protecting the Panama Canal...This is volume 16 in the original Tom Swift series