"Hand me that wrench, Mark," called Professor Amos Henderson to a boy who stood near some complicated machinery over which the old man was working. The lad passed the tool over. "Do you think the ship will work, Professor?" he asked. "I hope so, Mark, I hope so," muttered the scientist as he tightened some bolts on what was perhaps the strangest combination of apparatus that had ever been put together. "There is no reason why she should not, and yet-"...