KATTERFELTO (or KATERFELTO), GUSTAVUS (d. 1799)  , quack doctor and conjurer, was born in Prussia . About 1782 he came to London, where his advertisements in the newspapers, headed " Wonders ! Wonders ! Wonders!" enabled him to trade most profitably upon the credulity of the public during the widespread influenza epidemic of that year . His public entertainment, which, besides conjuring, included electrical and chemical experiments and demonstrations with the microscope, extracted a flattering testimonial from the royal family, who witnessed it in 1784 . The poet William Cowper refers to Katterfelto in The Task; he became notorious for a long tour he undertook, exciting marvel by his conjuring performances .