316 Intelligence and Miscellaneous Articles. 
certain particular cases, so that its experimental verification has been 
confined within very narrow limits. 
To effect this verification in a more general manner, I have ope- 
rated as follows :—I commenced by observing the asymptotic curve 
generatrix of the surface of the meniscus raised by a plane; having 
measured the corresponding values of the ordinates above the level, 
for abscissz very close to each other, this curve was afterwards con- 
structed by points, and the area and position of the centre of gravity 
of the surface comprised between this curve and the two axes were 
determined hy experiment. The same determinations were effected 
for menisci raised by a great number of convex cylinders of different 
diameters, and by means of Guldin’s theorem the volumes of the 
solids generated by the revolution of these surfaces round the axes 
of their cylinders were calculated. In the same way the capillary 
surface of the liquid included between two parallel planes, placed at 
different distances (2a), was found: let h be the height above the 
level of the lowest point of this curve, 6 the area of the section of 
the semi-meniscus, and / the breadth of one plane; 2/(ha+6) will 
be the volume of the liquid raised. 
The quotients of all the volumes which we have just found for 
one liquid at the same temperature, divided by the corresponding 
contours of the solid bodies, must be equal amongst themselves 
if the hypothesis be correct, and must furnish the constant of 
capillarity 5 sin ¢ (in which ¢ is the designation of the complement 
of the angle formed by the extreme element of the curve with the 
wall). 
This process does not apply to concave cylindrical surfaces; in 
these we can only observe the elevation / of the lowest point of the 
surface, and this is what I have done with a great number of tubes 
of very small or very large diameter; in these two limiting cases the 
constant of capillarity is deduced from the value of / alone, by means 
of the well-known formulz of Poisson. 
Lastly, in order to avoid being entirely deprived of data with regard 
to tubes of middle size, I had several drawn in zinc; and after coat- 
ing their inner surfaces with wax, I immersed one extremity in a 
capsule filled with fused wax, and maintained at a temperature 
slightly superior to that of fusion. The ascension took place, and 
after cooling, the interior column retained very nearly its primitive 
height, and the meniscus its original surface ; so that after dissolving 
the wall by dilute sulphuric acid, there remained a cylinder of wax 
terminated above by this surface, and below by a plane, the position 
of which in relation to the level had been previously determined: h 
was then measured, and the value of 4 determined upon a vertical 
section passing through the axis. The following Table contains the 
averages of all the results which I have obtained :— 
