56 MOTION OF THE 



either using such a fillet as is employed in bloodletting, or 

 grasping the limb lightly with his hand, the best subject for it 

 being one who is lean, and who has large veins, and the best 

 time after exercise, when the body is warm, the pulse is full, 

 and the blood carried in larger quantity to the extremities, for 

 all then is more conspicuous ; under such circumstances let a 

 ligature be thrown about the extremity, and drawn as tightly as 

 can be borne, it will first be perceived that beyond the ligature, 

 neither in the wrist nor anywhere else, do the arteries pulsate, 

 at the same time that immediately above the ligature the artery 

 begins to rise higher at each diastole, to throb more violently, 

 and to swell in its vicinity with a kind of tide, as if it strove 

 to break through and overcome the obstacle to its current ; the 

 artery here, in short, appears as if it were preternaturally full. 

 The hand under such circumstances retains its natural colour 

 and appearance ; in the course of time it begins to fall somewhat 

 in temperature, indeed, but nothing is drawn into it. 



After the bandage has been kept on for some short time in this 

 way, let it be slackened a little, brought to that state or term 

 of middling tightness which is used in bleeding, and it will be 

 seen that the whole hand and arm will instantly become deeply 

 suffused and distended, and the veins show themselves tumid 

 and knotted ; after ten or fifteen pulses of the artery, the hand 

 will be perceived excessively distended, injected, gorged with 

 blood, drawn, as it is said, by this middling ligature, without 

 pain, or heat, or any horror of a vacuum, or any other cause 

 yet indicated. 



If the finger be applied over the artery as it is pulsating by 

 the edge of the fillet, at the moment of slackening it, the blood 

 will be felt to glide through, as it were, underneath the finger ; 

 and he, too, upon whose arm the experiment is made, when the 

 ligature is slackened, is distinctly conscious of a sensation of 

 warmth, and of something, viz., a stream of blood suddenly 

 making its way along the course of the vessels and diffusing 

 itself through the hand, which at the same time begins to feel 

 hot, and becomes distended. 



As we had noted, in connexion with the tight ligature, that 

 the artery above the bandage was distended and pulsated, not 

 below it, so, in the case of the moderately tight bandage, 

 on the contrary, do we find that the veins below, never above, 



