a geometrician, celebrated on account of the invention of the curve called conchoid, which is equally useful in resolving the two famous problems of doubling the cube and trisecting the angle. It appears that he lived soon after Eratosthenes, for he rallied that philosopher on the mechanism of his mesolabos. Geminus, who flourished in the second century before Christ, has written on the conchoid, though Nicomedus was always esteemed the inventor of that curve. Those who place him four or five centuries after Christ must be ignorant of these facts, by which we are enabled to ascertain approximately the time at which he lived.