488 
The Measurements of the Pelvis 
against the skin so that the only part of the blade protruding from it was that 
extending from the skin to the bone. The length of this was read off and gave 
the thickness of the soft parts covering the bone. This was measured over the 
ischial tuberosity, and over the iliac crest in vertical and horizontal directions. 
The first two measurements, subtracted from the measurement already obtained 
for the height of the hip bone covered with tissues, will give the height of that 
bone in the moist state. By subtracting the thickness of tissues over the ilium 
in a horizontal direction from the maximum inter-cristal diameter previously 
measured, the length of that diameter in the moist pelvis free from tissues can 
be ascertained. 
The instrument was designed and made for us by Mr H. E. Soper of the 
Biometric Laboratory. 
(2) The relationship of the diameters and bone measurements to one another. 
The relationship of the diameters to one another was studied by means of the 
coefficient of correlation. As a preliminary, the average length and variability, 
as measured by the standard deviation, were found for each one. Emmons has 
already given the averages. Our results differ from his in some cases, probably 
owing to the fact that we divided the data into a larger number of groups. The 
diameters and bone measurements considered, together with the average and 
standard deviation of each, are shown in the following table. For the purpose 
of comparing the variabilities, the coefficients of variation are also given. All 
measurements in this and subsequent tables are expressed in centimetres. 
TABLE I. 
Average 
Standard 
Deviation 
Coefficient 
of 
Variation 
Inter-cristal... 
25-77 + 
•07 
1-44 + 
•05 
5-57 + 
•18 
Inter-spinous 
22-66 + 
■08 
1-65 + 
•05 
7-28 + 
•24 
Transverse (brim) ... 
12-97 + 
•03 
•72 + 
•02 
5-56± 
•18 
Diagonal conjugate 
12-14 + 
•05 
1-02 + 
•03 
8-44 + 
•28 
Obstetric conjugate 
10-32 + 
•05 
1-10 + 
•04 
10-62 + 
•35 
Antero-posterior (outlet) ... 
11-61 + 
•04 
•90 + 
•03 
7-76 + 
•25 
Inter-tuberal 
9-78 + 
•04 
-90 + 
•03 
9-22 + 
•30 
Posterior sagittal ... 
7-56 + 
•04 
•82 ± 
•03 
10-89 + 
•36 
Pubic height 
2-81 ± 
•02 
•52 ± 
•02 
18-30± 
•62 
Right hip — height ... 
19-26 + 
•05 
1-02 + 
•03 
5-27 + 
•17 
,, ,, breadth 
Left hip — height 
14-52 + 
•04 
•87 + 
•03 
5-97 + 
■19 
19-32 + 
•05 
1 -03 + 
•03 
5-32 + 
•17 
„ ,, breadth ... 
14-49 + 
•04 
•83 + 
•03 
5-72 + 
•19 
Sacrum — height 
10-00 + 
•05 
1-15 + 
•04 
11-52 + 
•38 
,, breadth ... 
11-47 + 
•03 
•66 + 
•02 
5-71 + 
•19 
The pubic height is the most variable of all the measurements. Of the 
diameters the transverse and inter-cristal show the least variability. The height 
