On October 15, 1973, Peter Jenkins set out with his dog Cooper to walk across the country, a beguiling idea; but he's such a limited observer and trite writer that this record of the trip so far (Colorado, June 1978) never goes anywhere. Just divorced, a college grad with no direction or goal, he sounds disingenuous from the start (""My problem was that I thought all towns in America were just like Greenwich"") and, despite several maturing experiences, he never seems to grow beyond superficialities and platitudes. ""This was my dream come true."" . . . ""My life flashed before me."" . . . ""That bit of wisdom would stay with me forever."" True, he stumbles on unforgettable characters like Homer the mountain man; observes at some length the black Olivers in North Carolina and the communal Farm in Tennessee; enjoys a royal welcome from George Wallace and a surprising religious moment at a revival meeting. He also calls home collect once a week. But his descriptions are barely adequate. Every noun has a standard adjective--like a Howard Johnson's menu--and most sentences sound forced and lifeless. ""This priceless gift from that unknown man totally renewed my tired body and desolate spirit."" And what he makes of these encounters is hardly revelational. ""This young policeman in his darkblue uniform and me with my weather-torn clothes, beard, and backpack both felt similar things about our 197-year-old country."" Reader's Digest will condense it and the publisher will promote its cherry-on-top pieties; we'll just admire the plan and regret its empty treatment.