A. B. Emmons 
37 
measured in life without difficulty in small pelves by means of two fingers through 
the vagina. To calculate the vera after obtaining the diagonal conjugate the inner 
surface of the pubic symphysis is palpated and two points observed ; first, the height 
of the point nearest the promontory above the symphysis (Diagram I, R — P); 
second, the angle which the line on which these two points lie makes with the 
diagonal conjugate (Diagram I, R — P — A). From these data we may calculate 
in each case the amount to be subtracted from the diagonal conjugate to give 
us the obstetric conjugate or vera (Diagram I, AP - NP '= AR). This difference 
(NP) was calculated in the dried specimens, and found to vary from 0'8 cm. to 
3'2 cms. in my series. 
The following table gives the data used in the living for estimating the 
"obstetric diameter" or the conjugata vera. The pubic height was taken from 
the point on the pubic symphysis nearest the promontory, as an upper limit, to 
the point on the pubic symphysis nearest the tip of the sacrum, as the lower limit, 
which space may be called the length of pubic resistance (see Plate VI, 6 and 
Diagram I, R — P). 
Oblique Diameter 
Freq. 
Obstetric Diameter 
Freq. 
Difference 
Freq. 
Pubic Height 
9-4 to 9-9 cms. 
4 
7 "5 to 8 "9 cms. 
14 
0-8 to 1-4 cms. 
46 
1-1 to 1-9 cms. 
9 
10 to 10-9 „ 
17 
9 to 9-9 „ 
60 
1-5 to 1-9 „ 
98 
2 to 2-9 „ 
109 
11 to 11-9 „ 
74 
10 to 10-9 „ 
75 
2 to 2-4 „ 
58 
3 to 4-3 „ 
95 
12 to 12-9 „ 
73 
11 to 11-9 „ 
54 
2-5 to 3-2 „ 
14 
broken 
4 
13 to 13-9 „ 
38 
12 to 12-9 „ 
10 
14 to 14-9 „ 
10 
13 to 14 „ 
4 
Average 11 '78 cms. 
Maximum 14'9 „ 
Minimum 9 - 4 ,, 
10-68 cms. 
14 
7-5 „ 
1*76 cms. 
3-2 „ 
0-8 „ 
2 - 8 cms. 
4-3 „ 
1-1 „ 
The antero-posterior distance being thus estimated, we turn to the measure 
of the width of the inlet, the transverse diameter. This distance cannot be 
satisfactorily measured in the living. Estimates of this diameter made in the 
usual way from the maximum inter-cristal and inter-spinous diameters are suggestive 
but unreliable, as demonstrated by Scheffer (6), who reported a difference of 
3'3 cms. in the inter-cristal measures of two pelves with equal transverse diameters. 
My series contains two rather narrow pelves (#62 and # 200), the comparison of 
which bears on this point ; one a generally contracted or " pygmy " pelvis, the 
other simply narrow. Three pelves, moreover, with nearly equally broad inlets, 
show wide variations in their inter-cristal diameters : — ■ 
362 crests 20 '8 cms. 
spines 17 "2 
transverse 10 - 7 
obstetric diameter 8*5 
8200 „ 23 „ 
„ 19-5 
10-3 
11 
&30 „ 25-5 „ 
„ 23-25 
14 
9-8 
5112 „ 29-1 „ 
„ 25 
14-1 
12 
(143 „ 25-5 „ 
„ 22 
14 
9-2 
