The greater width of the pubic arch in the female pelvis is seen by comparing its angle with that of the arch in the male pelvis. In the female it has been estimated to form an angle varying between 90° and 100°, whereas in the male it is not more than between 70° and 80°. (Osiander, _Handbuch der Embindungs-kunst_, cap. iv. p. 58.) From the greater width of the female pelvis, the acetubula are farther apart, and the great trochanters of the thigh-bones more projecting; hence the greater motion of the hips in the female when she walks, which is still more visible when she runs, for the motion is communicated to the whole trunk, so that each shoulder is turned more or less forwards as the corresponding foot is advanced. The thigh-bones, which are so far apart at their upper extremities, approach each other at the knees, contributing to produce that unsteady gait which is peculiar to the sex. "The woman," says Mr. John Bell, "even of the most beautiful form, walks with a delicacy and feebleness which we come to acknowledge as a beauty in the weaker sex." (_Bell's Anat._ vol. i.) These characteristic marks of the female figure, upon which its beauty in great measure depends, are well seen in all great works of art, whether of sculpture or painting. "The ancients," as Mr. Abernethy has observed, "who had a clear and strong perception of whatever is beautiful or useful in the human figure, and who, perhaps, delicately exaggerated beauty to render it more striking, have represented Venus as measuring one-third more across the hips than the shoulders, whilst, in Apollo, they have reversed these measurements." (_Physiological Lectures._) _Diameters of the pelvis._ It is of the utmost importance to the obstetrician, that he should be thoroughly acquainted with the various dimensions of the female pelvis, for, without this, he can form no correct idea of the manner in which the presenting part of the child passes through its brim, cavity and outlet during labour; indeed, unless he be thoroughly versed in this necessary point of obstetric knowledge, he will remain in almost total ignorance of the whole mechanism of parturition, which must, in great measure, be looked upon as the basis of practical midwifery. The dimensions of the brim cavity and outlet of the pelvis may be given with sufficient correctness for all practical purposes, by measuring three of their diameters,--1. the _straight_, _antero-posterior_, or _conjugate_; 2. the _transverse_; and 3. the _oblique_. At the brim they are as follow:--the straight diameter, drawn from the middle of the promontorium sacri to the upper edge of the symphisis pubis, 4·3 inches; the transverse diameter, from the middle of the linea-ilio-pectinea of one ilium to that of the other, 5·4 inches; and the oblique diameter, from one sacro-iliac synchondrosis to the opposite acetabulum, 4·8 inches. The oblique diameters are called right and left, according to the sacro-iliac symphysis from which they are drawn.