The only thing easier than throwing together a book on the presidency in an election year is to paste together one you've already written. Hersey, novelist and journalist, spent a few days hanging around the White House in 1950 and '51 watching Harry Truman at work, and looked in again in 1975 when Jerry Ford was there. The first visit was written up in The New Yorker, the second in The New York Times Magazine. What's more, Hersey has already gotten double-duty out of the Ford material--it was published in 1975 as The President. The only faint excuse for combining these stories is that both Truman and Ford happen not to have reached the White House by election, though Truman was already in his second term when Hersey showed up. Aside from this coincidence, the only other similarity is the tedium of hour-by-hour reconstructions of a day in the life of a president. Hersey went walking with Truman before breakfast and watched Ford exercise at 6 a.m. (to judge by this account, the first qualification for president is getting up at 5:30). He got such hopeful insights as the news that Ford ate the same lunch every day: cottage cheese with Al sauce, onion or tomato, and butter pecan ice cream. ""Eating and sleeping,"" Ford explains, ""are a waste of time."" Truman comes across as preoccupied with his career and the responsibilities of office, while Ford works on his joke delivery and legislative vetoes. Hersey's sympathies are clear, but his purpose is not; there's no real point here other than opportunism.