I now come to some points in the structure of the glacier, the consideration of which is likely to have a decided influence in settling the conflicting views respecting their motion. The experiments of Faraday concerning regelation, and the application of the facts made known by the great English physicist to the theory of the glaciers, as first presented by Dr. Tyndall in his admirable work, show that fragments of ice with most surfaces are readily reunited under pressure into a solid mass. It follows from these experiments, that glacier-ice, at a temperature of 32 deg. Fahrenheit, may change its form and preserve its continuity during its motion, in virtue of the pressure to which it is subjected. The statement is, that, when two pieces of ice with moistened surfaces are placed in contact, they become cemented together by the freezing of a film of water between them, while, when the ice is below 32 deg. Fahrenheit, and therefore _dry_, no effect of the kind can be produced. The freezing was also found to take place under water; and the result was the same, even when the water into which the ice was plunged was as hot as the hand can bear. The fact that ice becomes cemented under these circumstances is fully established, and my own experiments have confirmed it to the fullest extent. I question, however, the statement, that regelation takes place _by the freezing of a film of water between the fragments_. I never have been able to detect any indication of the presence of such a film, and am, therefore, inclined to consider this result as akin to what takes place when fragments of moist clay or marl are pressed together and thus reunited. When examining beds of clay and marl, or even of compact limestone, especially in large mountain-masses, I have frequently observed that the rock presents a net-work of minute fissures pervading the whole, without producing a distinct solution of continuity, though generally determining the lines according to which it breaks under sudden shocks. The net-work of capillary fissures pervading the glacier may fairly be compared to these rents in hard rocks,--with this difference, however, that in ice they are more permeable to water than in stone.