A. B. Emmons 
39 
as possible- For simplification the oblique diameters of the inlet, which cannot 
be measured on the living, were not included. 
Outlet. The pelvic outlet is commonly of very secondary importance as 
compared to the inlet. The space is a complicated one of irregular outline, 
and has received much less attention for these reasons. Occasional extreme 
contractions of this space have been recorded, usually, however, only after 
disastrous results of labour have occurred. The subject has lately been thoroughly 
reviewed historically from an obstetrical standpoint by Williams (8), who gives 
also his clinical observations on 1200 women. In analyzing this complex space 
a few special measurements were taken in the hope of rendering more simple 
and more exact the observations necessary for its estimation (see Plates III, VI, 7, 
VII, 8, 9, 10, and Diagrams I, II, and III). 
Diagram I (traced from Plate VI, 7, pelvis J 106). 
Diameters of the Inlet. Planes of the Outlet. 
A. Promontory. 
K. Nearest point of pubic symphysis to promontory. 
A — E. Inlet, obstetric diameter, or vera. 
P. Nearest point of pubic symphysis to sacrum. 
K — P. " Height of Pubic Kesistance." 
A — P. Diagonal conjugate. 
N — E. Perpendicular from diagonal conjugate to obstetric conjugate. 
N — P. Amount subtracted from diagonal conjugate to obtain obstetric conjugate. 
S. Tip of sacrum. 
T. Tuberosity, point of impingement. 
S — P. Antero-posterior diameter of the outlet. 
0 — T. Perpendicular from antero-posterior diameter of outlet to inter-tuberal diameter. 
S — T. Posterior sagittal diameter. 
P — 0. Pubic symphysis to foot of perpendicular. 
