371 
of Edinburgh, Session 1870-71. 
tained, is of course a measure of the power employed ; at least, it 
would afford a valuable result as to the limits of the power. Like 
statements might be made regarding the laceration of the margin 
of the cervix uteri, as a test of the power exerted at the completion 
of the first stage of labour. Many methods were available, but 
none were till very recently worked out. 
It is probable that many intelligent and thoughtful accoucheurs 
had some rough ideas as to the amount of power exerted in partu- 
rition. They could not fail, in attending on ordinary labours, to 
observe the strength of hand and arm required to keep back the 
head too rapidly advancing over a delicate perineum. This power 
is, under certain conditions, a measure of the force of the labour, 
but I am not aware that any one has hitherto made the simple 
and proper dynamometrical experiments to decide the amount of 
force so exerted by the accoucheur. The problem may be more 
exactly stated as follows : — If in an unobstructed and powerful 
labour, the accoucheur, by the directly opposing pressure of his 
hand on the foetal head, arrests its progress for one or several 
pains, he has in the pressure of his hand a force which, added to the 
small amount required to effect parturition, exceeds all the com- 
bined powers of labour in this case. He may then estimate by 
dynamometrical experiment what was the force he used, or what 
force he is capable of applying in the way in which he actually 
applied it to arrest the progress of labour. This experiment may 
be varied in different ways, of which I may mention one. Let us 
suppose a case of rigid vulva, the perineal resistance being over- 
come, and the head retroceding during the interval between 
powerful bearing down pains. Now, it is well known that in such 
a case a little manual pressure from above may be enough to push 
the head down again on the perineum, or to resist retrocession, or 
that the first and painless part of the next pain will make the head 
that has retroceded, again bulge out the perineum, before it is 
forced by the powerful acme of the pain against the resisting 
vulva. If, then, the practitioner opposes the advance of the head 
even so far as to bulge out the perineum, he must have a nearly 
exact measure of the force which the labour could bring to bear 
against the vulvar obstacle. 
In such experiments or practice, what force does the accoucheur 
