John Ridgway got the idea of navigating the Amazon from its highest source in Peru to its mouth while he was rowing a 20-foot dory from North America to Ireland in 1966. Five years later he managed to assemble three others for the adventure and they set out for Lima, all of them strangers--could strangers weld themselves into a team under these stringent conditions? Ridgway himself is something of a student of adventure, and the others were an entomologist, a photographer, and a girl identified as ""the third fastest downhill skier of all time."" (All the men, it should be said, were happily married while Anna, strained by the rigors of the journey, had to assume a lofty, separatist attitude just to keep up and keep going.) The journey moves from the arctic conditions of the Andes at 15,000 feet to the habitat of maddeningly dense insects and vampire bats in the equatorial region. The travelers arrive at the heights too quickly and get sick from oxygen starvation while trying to locate the big river's origins (maps are very poor indeed). But push on they must in a race against the rainy season. Thanks to good planning, they manage to overcome their own blunders and the language problems with Indians along the way. They cope so well, indeed, that the story is more a National-Geographic cultural study than it is a perilous adventure. There is less river travel too, than you might expect, though the highpoint is a briefly calamitous raft wreck. A lively travelogue with some burrs and scratches.