WITHDRAWN FROM THE ACTION OF GRAVITY. 679 



quently at the commencement is extremely small. In conse- 

 quence then of this original minuteness and of the velocity of 

 the movement of transference in the vein, the effects of the gra- 

 dual transformation cannot begin to become obvious until a 

 greater or less distance from the contracted section has been 

 attained. Up to this distance the rapid passage of the dilata- 

 tions and constrictions before the eye cannot give rise to any 

 effect \dsible to the simple sight ; so that this portion of the vein 

 will appear in the form which it would affect if it had no tendency 

 to become divided. Beyond this distance the dilatations will 

 begin to acquire considerable development ; the vein will appear 

 to continue enlarging until another distance has been attained 

 beyond which the diameter will appear constant. Such is^ in 

 fact, as the observations of Savart have shown, the form pre- 

 sented to direct observation by a vein withdrawn from the in- 

 fluence of any disturbing cause. 



Lastly, we know that from the orifice to the point at which it 

 appears to begin to enlarge, the vein is seen to be limpid, whilst 

 further on it appears more or less turbid ; and Savart has per- 

 fectly explained these two different aspects, as also some other 

 curious appearances which the ti'oubled part presents, by attri- 

 buting the limpidity of the upper portion to the slight deve- 

 lopment of dilatations and constrictions which are propagated 

 in it; and the turbidity, as also the other appearances of the 

 remainder of the vein, to the rapid passage before the eye, at 

 first of the dilatations and constrictions which have become 

 more marked, then lower down, of the isolated spheres and the 

 interposed spherules. We must refer for the details to the 

 memoir quoted above. 



71. But we may go further : two consequences spring directly 

 from our explanation of the constitution of the vein. In the 

 first place, as the divisions become transfoi'med during their 

 descent, it is clear that the space traversed by a division during 

 the time it is effecting a given part of its transformation, will be 

 as much greater as it descends more rapidly, or, in other words, 

 as the charge, i. e. the height of the liquid in the vessel, is more 

 considerable ; whence it follows clearly, that, the orifice being 

 the same, the length of the continuous part of the vein must in- 

 crease with the charge. Now this has been confirmed by Savart's 

 observations. In the second place, since the transformation of 

 a cylinder is slower in proportion to the size of its diameter, the 



