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The cataract knives of Richter, Wenzel, Ward, and others, being intended to perform the section of the transparent cornea, are so shaped as to exactly fill the small wound made by them; and thus to prevent the discharge of the aqueous humour, until the section is completed. The blade of the knives of Wenzel and Ward resembles a very narrow lancet, blunt in the posterior five-sixths of one of its edges. The blade of that of Richter is pyramidal, cutting through the whole length of its inferior edge, and also blunt in the five-sixths of the upper.