160 
the resistance offered by solid materials. In the second 
place I have to describe certain experimental results which 
as far as they go completely verify these conclusions and 
subvert the general ideas previously mentioned as to the 
limits to the height to which mercury can be suspended in 
a tube or water raised by suction. And in conclusion I 
shall endeavour to explain the nature of the circumstances 
which have resulted in the practical limits to these phe- 
nomena. 
The Separation of Liquid is not caused by Rupture. 
Although the smallness of the force generally requisite to 
separate a mass of liquid into parts leads to the supposition 
that the parts of the liquid have but little coherence, it may 
be seen on close examination that this supposition is not 
altogether legitimate. For such separation of a liquid as we 
ordinarily observe takes place at the surface of the liquid — 
is caused by an indentation or running in of the surface, and 
not by an internal rupture or simultaneous separation over 
any considerable area. Thus, when we see a stream of liquid 
break up into drops, the drops separate gradually by the con- 
Fig 2 ^ rac ^ on the necks joining them, 
as shown in fig. 1, and not suddenly 
as in fig. 2. And the ease with 
which portions of a liquid may be 
separated by the forcing or drawing 
in of the surface affords no ground 
for assuming that the liquid is with- 
out coherence, any more than does 
J • the ease with which we may cut a 
piece of string, cloth, or metal with 
sharp shears, or even tear some of these bodies by beginning 
at an edge, prove that they are without strength to resist great 
force when these are applied uniformity so as to call forth 
the resistance of all the parts of the body simultaneously. 
It is true that under certain circumstances we observe the 
Fig. 1. 
