The reappearance of chimney sweeps, combined with their earlier incarnation as pitiable small boys, makes for an appealing, instructive mix of technological, economic, and social history. After juxtaposing a pair of modern, vacuum-cleaner-equipped sweeps with yesteryear's scrambling, bare-chested lad (emerging jubilantly from the chimney, in Margot Tomes' puckish picture), Giblin explains why and how chimneys were first built, and the need for sweeps arose. In Germany, we learn, sweeping became a regular, regularized profession in the 1400s when twice-yearly cleaning of chimneys was mandated. (On the Continent, mandatory sweeping, and greater respect for sweeps, has been the norm.) But it was in England, in the 1700s--when flues grew smaller and more crooked, and sooty coal replaced cleaner-burning wood--that recourse was had to young boys, ""small enough to crawl up the new chimneys and clean out the soot by hand."" Giblin reconstructs a climbing boy's day; recounts the efforts of reformers to improve their lot or, best of all, ban child sweeps; chronicles the different history of sweeps in America (where ""the boys were usually treated better""--except for the many who were black); and concludes with particulars on sweeps today. (Most do it in their spare time; women as well as men are involved; the pay can be very good.) As narrator, Giblin is commendably relaxed and precise--and there are curiosity-piquing present-day photos, as well as the storybookish illustrations.