The fact that the temporary closure of blood vessels by means of instrumental compression requires careful regulation of the pressure employed is fully recognized in the idea embodied in the Crile artery clamp. In this instrument the pressure brought to bear on the vessel is regulated by means of a small thumb screw acting against a spring resistance. In order either to apply or to remove this clamp the thumb-screw must be turned several times, the number depending on the size of the vessel and the thickness of its wall. This is the antithesis of the non-adjustable spring clamp commonly used in experimental work which may be instantly applied or removed by compressing it with the thumb and forefinger, but which always has the same pressure whether too strong or too weak, and which is, therefore, entirely unsuited to clinical work.
As a result of clinical observation and of work