44 OF THE PELVIS. 



the superior strait. If the symphysis be at the same time depressed, 

 we may affirm that the sacro-pubic diameter is shortened, and that 

 the strait is bilobated, or of the figure of an oo . Hips uneven or 

 too much elevated, and depressed external iliac fossae disclose a 

 fault of the bis-iliac diameter. The approximation of the ischia, 

 the convexity of the sacrum, and the forward inclination of the coc- 

 cyx need only to be hinted at to render it easy even to the least 

 skilful person to recognise them in an instant. 



1 12. As it is essential to the happiness of families that we should 

 arrive at mathematical results, and as the employment of the hand 

 yields them only in a vague and approximative manner, the ac- 

 coucheurs have invented an infinity of instruments for the purpose 

 of exactly measuring the pelvis, whether externally or internally; 

 these instruments are called pelvimeters or mecometers. 



113. Only two of them can be applied externally; one, the {com,' 

 pas cVepaisseur) calliper of Baudelocque, which is almost exclu- 

 sively employed, on account of its simplicity; and the other, the 

 meconieter of Chaussier, which is scarcely used except at the Mater- 

 nite of Paris. The calliper serves to measure, 1. The sacro-pubic 

 diameter, by placing one of the buttons in front of the symphysis 

 pubis, and the other on the first spinous process of the sacrum; 2. 

 The oblique diameters, by placing one of the ends of the calliper 

 on the external surface of the great trochanter, and the other on the 

 projecting portion of the opposite sacro-iliac junction. In the first 

 situation, the cursor must measure seven inches; so that by deduct- 

 ing two inches and a half for the sacrum and half an inch for the 

 pubis, there may remain four inches for the antero-posterior diameter 

 of the superior strait. For the oblique diameters, it should measure 

 nine inches, for we must deduct two inches and three quarters for 

 the trochanter, the neck of the femur and the acetabulum, and one 

 inch and three-quarters for the posterior symphysis. 



114. Baudelocque has asserted that the thickness of the bones 

 rarely varies more than one or two lines in the antero-posterior dia- 

 meter, and that the results obtained by the calliper may be relied on. 

 Madame Lachapelle, on the contrary, regards this mode of proceed- 

 ing as very deceptive, and thinks the thickness of the sacrum may 

 vary from four to five lines. Madame Boivin goes still farther, for 

 she says the thickness indicated by Baudelocque varies from four to 

 twelve lines. One thing certain is, that leanness or fatness does not 

 diminish or increase in a sensible degree the thickness of the soft 

 parts, on the points to be touched by the instrument, and that the 

 differences of thickness of the sacrum and pubis mentioned by Mes- 

 dames Lachapelle and Boivin, are at least extremely rare. 



