J. LeConte—Horizontal Motions of Floating Bodies. 307 
* 
Arr. BER VI =i Horaondil Motions of small Floating Bodies 
tm relation to the Validity of the Postulates of the Theory of 
Capillarity ; by Joun LeConre. 
as pointed out in the articles of Mr. J. T. Riley an ir A. 
Worthington,+ served to fix my attention on the difficulties 
and ambiguities which invest one the most obscure an 
a. 
A more careful and somewhat prolonged consideration of 
these difficulties has led me to question the validity of one or 
more of the fundamental postulates of the generally accepted 
physical theory of capillarity, and to seek for a solution of some 
of these perplexities in the erroneous assumptions, 
hese postulates, as enunciated by the late Prof. J. C 
Maxwell (ncyc. Britannica, ninth edition, Article “ Capil 
ction”), may be stated as follows: : 
1. “For any given liquid surface, as the surface which sepa- 
fates water from air, or oil from water, the surface-tension 18 
the Same at ever int of the surface and in every direction. 
It is also practically independent of the curvature of the surface, 
although it appears from the mathematical theory that there is 
4 slight increase of tension where the mean curvature of the 
Surface is concave, and a slight diminution where it 1s convex. 
€ amount of this increase and diminution is too small to be 
Clerk- 
l 
ary 
breadth, that is, it must exert surface-tension. 
the sheet of india-rubber, however, depends on the extent to 
Which it is stretched, and may be different in different ese 
tions ; whereas, the tension of the surface of a liquid remains the 
- This Journal, III, vol. xxiv, pp. 416-425, December, 1882. Also Phil. Mag., 
Vol. xv, pp. 47-56, January, 1883. 
t Phil. Mag., for March, 1883, p. 191 et p. 198. 
+ Phil, Mag., for October and November, 1883, p. 309 et p. 339. 
