A WOLVERINE IS ATTACKING MY LEG: <i> by Tim Cahill (Vintage / Random House: $8.95) </i>

Why venture down dangerous Himalayan rapids or up 40-story-high underground precipices? To stir up enough endorphins to foster a feeling of exhilaration, Tim Cahill explains, and to escape inner demons. Cahill’s demon was the serial killer, which he studied for a book he wrote prior to taking some of the trips described in these pages: “Looking inside the mind of a murderer was terrifying. . . . In those bad, shaky times, when I realized that one more morbid detail, one more sordid fact, would send me screaming around the bend, I knew it was time to go out and risk my life for no very good reason.” Unlike many Gonzo travel adventures, though, these stories are not so obsessed with walking on the “razored precipice separating rational behavior from irrational” that they lose sensitivity to other people, animals and places.

While Cahill mitigates armchair reader envy through bad puns (“We have always depended on the kindness of rangers”) and bizarre quips (“In diving . . . you get to go around wearing tight rubber suits, and nobody thinks you’re weird: this is our little secret”), a few of these adventures are better experienced than read about. Several pieces, however, are as substantial as they are absorbing. “Love and Death in Gorilla Country,” for example, is an original, insightful look at an old story--Dian Fossey’s work with gorillas in Rwanda. Cahill is silly at times (he finds gorilla life to be “incredibly slow moving and predictable . . . like ‘Dallas’ on downers”), but he describes the apes vividly (they smell “skunky with a splash of vinegar”) and he sensitively portrays the political power struggles that doomed Fossey.

An impressive collection, exploring the way the beauty and the darkness of the physical world is mirrored in the human psyche. Cahill seeks out stress, quoting author Ralph Keyes, “to enjoy the subsequent tranquility . . . . Risk is a part of therapy; you can put your life on the line in order to save your soul.”