E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
A generic name for a quack or charlatan. Katerfelto was a celebrated quack or influenza doctor. He was a tall man, who dressed in a long black gown and square cap. In 1782 he exhibited in London his solar microscope, and created immense excitement by showing the infusoria of [muddy] water. The doctor used to aver that he was the greatest philosopher since the time of Sir Isaac Newton.