The first measurement is of the external conjugate (" C. ext."), frequently known as D.B., the diameter of Baudelocque. Now, the external conjugate is measured from what you judge to be the first spine of the sacrum, or from a hollow that is generally found below the last lumbar spine, to the mons veneris in front of the symphysis pubis. In a healthy woman that measurement is from seven and a half to eight inches ; I shall put it down at seven and a half. There are sources of variation which will easily suggest themselves to you, such as the different amount of fat in different women. Now for the judgment you form from this. You take off two and a half for the thickness of the sacrum ; you take off fully an inch for the thickness of the pubes and the soft parts — that is, you substract quite three inches and a half from seven and a half. If you had nothing else to rely upon, and you found the measurement seven and a half, you would say a four-inch pelvis — a healthy pelvis so far — four inches. But you will find in practice that this is not a very reliable measurement, therefore you take other measurements by which to correct this. It so happens that in the most interesting case I have to mention to-day the measurement proved correct, or as nearly correct as was to be expected. In this poor woman, whose pelvis I have in my hand, the external conjugate was five and a half ; take off fully three and a half, and you have left two inches, or somewhat less.
The next dimension you take is the measurement of the spines, as it is called. This measurement is from the external margins of the anterior superior spinous processes of the ilia, and it is known by the marks I show you here, " Sp. il." In healthy women this measurement varies greatly, and it is about ten inches. Then you take another measurement between the most distant parts of the crests of the ilia, and this is known in books as " Cr. il./ J and in healthy women generally measures eleven inches, or fully c
