flo6 Professor Weber's Description of' an 



of rarefaction of the air, which takes place on high mountains, 

 be such that the diminished pressure may be no longer suffi- 

 cient to support the weight of the bone, and if we should thus 

 be justified in attributing the fatigue to sucli a derangement 

 of the mechanism of the organs of motion. — We have really per- 

 formed this experiment during our residence in Berlin. 



A fresh pelvis, together with the thigh-bones, for which we 

 were indebted to Professor Schlemm, was divided through the 

 OS sacrum^ and the fragments of the pelvis, as well as the 

 thigh-bones, so cut as to admit of the hip-joints being easily 

 suspended under the receiver of an air-pump. Perpendicularly 

 above the hip-joint a hole was bored through the bone of the 

 pelvis, and a cord passed through it, in order by that means 

 to hang up freely the hip-joint. A second hole was bored per- 

 pendicularly under the joint through the thigh-bone; so that 

 a weight might be attached to it, which should come in place 

 of the bone that had been cut away. 



After having made these preparations in the laboratory of 

 Professor Magnus ; and assisted by him, and in presence of 

 Professor MiJller and my brother, I performed the following 

 experiment : — 



On the one hip-joint, the capsular membrane was cut through 

 close round the thigh-bone, so that it no longer united the tvvo 

 bones with each other. Those present convinced themselves 

 that this had really completely taken place, and still the two 

 surfaces of the joint were not only in perfect contact, but (by 

 the pressure of the air) were held fast together. Afterwards 

 the bone of the pelvis was secured by the upper cord to a hook 

 in the cover of the receiver. The apparatus was thus sus- 

 pended freely from the cover of the receiver, and high above 

 the plate on which the receiver was placed. To the thigh-bone 

 a heavy weight of two pounds was attached by a cord. The 

 height of the lowest hanging weight above the plate was mea- 

 sured by Professors Miiller, Magnus, and Weber ; and then 

 the air was withdrawn from the receiver, till its pressure was 

 diipinished to three Parisian inches of mercury. By this the 

 blood was driven out of the vessels of the bones, but the head 

 of the thigh-bone, together with the attached weights, pre- 

 served their original position. Scarcely, however, was the 



