This rather desultory anthology gathers some 72 sessions of C-SPAN's popular author-interview series, this time covering prominent nonfiction books on American history. As in the three previous Booknotes anthologies, the interviews are edited to remove host Lamb's side of the dialogue; at their best, they read like chatty, informal essays. But the fact remains that no amount of editing can impart to conversational exchanges the kind of structure, focus and polish that makes an essay readable. In consequence, these pieces--lacking the orienting and framing clues that the host's questions provide to the TV audience--tend to lurch from one topic to another, rarely settling down to a coherent theme. It doesn't help that so many of the books discussed are biographies, which can give rise to perfunctory first-he-did-this-and-then-he-did-that narrative rehashes. The most coherent and interesting pieces are the polemical ones, like Victor Davis Hanson's diatribe against American immigration policy and James Loewen's critique of high school American history texts, both of which have the vigorous drive of an oft-rehearsed stump speech. But none of them really surmounts the problem that, no matter how lively it may sound on TV, conversational English can be very tedious to read--coarse and flat, stripped of inflection and rhythm, full of stammering repetitions and the sort of vivacious colloquialism (""For example, Union Station in Washington D. C., in 1909, she busted up a saloon and who knows? I'm not sure why she did that"" blurts Fran Grace about temperance crusader Carrie Nation) that comes off as discombobulated rambling on the page. There are eminent personages aplenty in here, but they're not shown in their best light.