Dr. Otis, the elder, in order to be able to treat each patient from the standpoint of that individual, resorted to the comparison by measurement of the circumference of the urethra with the circumference of the penis. This he did in hundreds of cases, and he found that they bore a nearly fixed relation one with the other—not exactly, but near enough for the purpose of forming a working basis. After the measurements of these hundreds of cases, when he had become sure of his premises, he made the results of his labors and investigations known. He found that a penis measuring three inches in circumference gave a urethral circumferential measurement of thirty millimetres, and for every eighth of an inch difference in the circumference of the penis there was a difference of one millimetre in the circumference of the urethra.
J Cutan Genito-Urin Dis.
THOMAS JD. THE MANAGEMENT OF FILIFORM STRICTURE OF THE URETHRA, WITH SOME OBSERVATIONS ON STRICTURE. Arch Dermatol. 1996;132(5):502. doi:10.1001/archderm.1996.03890290028004