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piece of ice is brought under water against the side of another float- 

 ing piece, it will stick to that piece like a leech. He showed that if 

 the pieces be allowed to remain for a few moments in contact, their 

 adhesion will become rigid, so that on a force being applied sufficient 

 to break through the joint, the rupture will occur with a crackling 

 noise, though the pieces may still continue to hold together, rolling 

 on one another with the flexible adhesion. He made some other ex- 

 periments nearly the same as these, but in which he showed the 

 flexible and rigid adhesion to occur while there is constantly a decided 

 tensile force applied externally tending to pull the pieces asunder 

 instead of any external force tending to press them together. He 

 thinks that the phenomena of flexible and rigid adhesion " under 

 tension" go towards showing that pressure is not necessary to " rp- 

 gelation." He then gives his own idea of the flexible and rigid 

 adhesion in the following words : " Two convex surfaces of ice come 

 together ; the particles of water nearest to the place of contact, and 

 therefore within the efficient sphere of action of those particles of ice 

 which are on both sides of them, solidify ; if the condition of things 

 be left for a moment, that the heat evolved by the solidification may 

 be conducted away and dispersed, more particles will solidify, and 

 ultimately enough to form a fixed and rigid junction, which will 

 remain until a force sufficiently great to break through it is applied. 

 But if the direction of the force resorted to can be relieved by any 

 hinge-like motion at the point of contact, then I think that the union 

 is broken up amongst the particles on the opening side of the angle, 

 whilst the particles on the closing side come within the effectual 

 regelatiou distance ; regelation ensues there and the adhesion is 

 maintained, though in an apparently flexible state. The flexibility 

 appears to me to be due to a series of ruptures on one side of the 

 centre of contact, and of adhesion on the other, the regelation, 

 which is dependent on the vicinity of the ice surfaces, being trans- 

 ferred as the place of efficient vicinity is changed. That the sub- 

 stance we are considering is as brittle as ice, does not make any dif- 

 ficulty to me in respect of the flexible adhesion ; for if we suppose 

 that the point of contact exists only at one particle, still the angular 

 motion at that point must bring a second particle into contact (to 

 suffer regelation) before separation could occur at the first ; or if, as 

 seems proved by the supervention of the rigid adhesion upon the 



