258 Professor Weber's Experiment on the Thigh-bone, ^c, 



the thigh, together with the attached weights, could be safely 

 supported. 



We had intended to perform this experiment on the other 

 hip-joint in a still more modified form. It turned out, how- 

 ever, that in taking out the joint the incisura acetahuli had 

 been too much exposed, so that the air had penetrated into the 

 fat and cellular tissue contained in it, when we loaded the thigh- 

 bone without the receiver ; so that the weight even in the open 

 air separated somewhat the surfaces of the joint from each 

 other. Those present, however, convinced themselves that 

 these surfaces were closely drawn together, and could only be 

 torn asunder by great violence, whenever we covered the inci- 

 sura with the finger, and thus kept off the pressure of the air. 



These experiments not only confirm generally the accuracy 

 of Humboldt's supposition, but may also serve more particu- 

 larly to decide, if the rarefaction of the air on high mountains 

 be sufficient to produce this phenomenon. For they have 

 proved that about two and a half pounds (the weight of the 

 cut off thigh bone, and the attached weight of two pounds), 

 supported when the barometer marked three inches, could no 

 longer be supported when there was a small diminution of the 

 pressure. If we reckon the weight of the whole bone at twenty 

 pounds, that is eight times greater, then a pressure of twenty- 

 four inches quicksilver would be sufficient to support the whole 

 bone. If, therefore, the barometer sinks below twenty-four 

 inches on high mountains, so during walking the muscles of the 

 bone that is raised, and is swinging above the ground, can 

 no longer be idle, but must be so exerted, that for every inch 

 the mercury sinks, they must carry five-sixths of a pound ad- 

 ditional. In consequence of this unusual continued straining, 

 the muscles will not only become fatigued, but, as this strain- 

 ing is opposed to the swinging which ha? to be performed by 

 the bone, a feeling of uneasiness and inconvenience occurs in 

 walking, which seems to explain the described sensation of fa- 

 tigue. 



It deserves to be remarked, that in spontaneous lameness, — 

 where the bone is no longer held in its place by the pressure of 

 the atmosphere, but even in the beginning of the disease, sinks 

 so far out of the socket, as is permitted by the capsular mem- 

 brane — also a speedy and considerable fatigue is perceptible in 



