WITHDRAWN FROM THE ACTION OF GRAVITY. 655 



In the above series, neither of the results appears to be very- 

 regular; but we can readily understand that the mean of the 

 values of the third column will approach the normal length of 

 the divisions. This is moreover confirmed by the tables in §§ 54 

 and 55: if we take in the former the respective means of the 

 values of the two series, we find for one 6'77 niillims., and for 

 the other 7*17 millims., quantities, the first of which is nearly 

 equal to the length 6*67 millims., which may be considered as 

 the normal length, and from which the second does not diflfer 

 much ; and if likewise we take the relative mean in the following 

 table, we find 13*15 millims., a quantity very near the length 13*33 

 millims., which in the case of the second table may also be re- 

 garded as the normal length. Now, the corresponding mean 

 in the above table is lO'Sl millims.; consequently, in the case 



10'81 

 of two lines of contact we have ^ ^. =10'29 as the approxi- 



1'05 



mate value of the proportion of the normal length of the divi- 

 sions to the diameter of the cylinder, whilst in the case of a 

 single line of contact we found only 6*35 . Hence the propor- 

 tion between the normal length of the divisions and the di- 

 ameter of the cylinder increases by the eflfect of an external 

 resistance. 



59. Let us proceed to the influence of the nature of the liquid. 

 All liquids are more or less viscid, i. e. their molecules do not 

 enjoy perfect mobility with regard to each other. Now this 

 gives rise to an internal resistance, which must also render the 

 transformation less easy ; and as external resistances increase the 

 length of the divisions, we can understand that the viscidity will 

 act in the same manner, consequently all other things being 

 equal, the proportion now under consideration will increase with 

 this viscidity. But on the other hand, with equal curvatures, the 

 intensities of the forces which produce the transformation vary 

 with the nature of the liquid ; for these intensities depend, in 

 the case of each liquid, upon that of the mutual attraction of the 

 molecules. Now it is clear that the viscidity will exert so much 

 more influence upon the length of the divisions as the intensities 

 of the forces in question are less. Thus, leaving external re- 

 sistances out of the question, the proportions of the normal length 

 of the divisions to the diameter of the cylinder will be greater in 

 proportion to the viscidity of the liquid and the feebleness of the 

 configuring forces. 



2 Y 2 



