The set of ten rods is thus equivalent to four sets of slips as described above, and by their means we may multiply every number less than II,**irr**, and also any number (consisting of course FIG.

Dividing **irr** 2 p by this length we obtain zpr as the value of the intensity of the surface-tension, and it is plain from equation 8 that this is equal to T.

13) are the disks, and if x the distance between the disks is equal to **irr** half the wave-length of the harmonic curve, the disks will be at the points where the curve is at its mean 1 3.

If A 1, C 1 are the disks, so that the distance between them is less than **irr**, the curve must be produced beyond the disks before it is at its mean distance from the axis.