. . . . . . . . . . . . . . . . . . . . . "1740" . . . . . . . . . . "1827" . "John Haygarth" . . "John Haygarth" . "John Haygarth's" . . . . . . "the (1799) investigations of Chester physician John Haygarth (1740-1827) into the efficacy of Perkins' \\\"tractors\\\"" . . .