“Three stars is enough for a fix,” he shouted above the engines’ thunder. “Just wait till I shoot Venus.” “Better not—it might really be Sirius!” punned Barry. “Anything I can do to help?” “Thanks,” replied the navigator, as he prepared to step down, “Just open your mouth again and I’ll put my foot in it.” Barry dodged, just in time to tumble over Fred Marmon who “accidentally” happened to be crouched just behind him. As he picked himself up, even sad-eyed Tony Romani laughed. The crew’s tense nerves were relaxing. Whistling a few bars from _Pagliacci_, the mustachioed navigator went back to his desk. Curly Levitt was still a bit worried, however. On the accuracy of his reckoning depended the life of every man on board. If he failed, the chances were excellent that _Sweet Rosy O’Grady_ would plunge to a watery grave the moment her gas supply gave out. At best she would crash in the Venezuelan jungle—unless, of course, the clouds broke up farther on and showed her crew a landing field. “Check this reckoning with me, will you, Blake?” Levitt invited. “Then if there should be an error we can blame it on the wallop my octant took in the storm.” “Okay!” Barry agreed. “If your octant is off, we’ll probably find it out too late to help ourselves. So don’t worry.” Reckoning the fix is really a simple matter. At a given time only one point on the earth’s surface can be directly under any star. Using his octant, the navigator “shoots” or measures the elevation of two or more stars, and then figures out just where each “substellar” point is on the earth’s surface. His next step is still easier. With his substellar points located on the map, he draws circles around them. One of the places where these circles intersect is the place where his plane was at the time the stars were “shot.” There is no real difficulty in guessing which intersection is the right one: the others are apt to be thousands of miles from his last known position. Everything, of course, depends upon the accuracy of the star-shooting octant. This expensive and delicate instrument will not always stand abuse such as Curly Levitt’s had taken. There was reason for the young ex-lawyer to be worried. He slipped on his headset and switched on the interphone. The click in his ears told him that it still worked. “Pilot from navigator,” he said. “If I’m right we’re fifty miles due north of Cayo Grande. Our present compass course would take us just past the southern tip of Trinidad. That checks pretty well with my dead reckoning. I haven’t had an accurate drift reading since we banged into that front.” “Navigator from pilot,” came the drawling reply. “_Rosy_ says she’ll take your word for it. She likes your style, hombre, even if you _are_ a lily-fingered product of the effete East. A man who can keep _any_ sort of dead reckoning in a storm like the one we just rode through will do to cross the river with.”