XVIII. On the ice formed, under peculiar circumstances, at the bottom of running water

Abstract

Ice formed at the bottom of rivers and streams, frequently in great quantities, is a phenomenon quite common in this climate. I made for several years past a number of incidental and desultory observations upon it, and became convinced that the principal explanation of its occurrence is the radiation of heat from the solid opake materials of the bottom; but as I conceived this to be also the generally admitted one, I took no note of the observations, with the view of vindicating the theory of the radiation. It appears, however, from a paper of M. Arago upon the subject, translated and published in the Edinburgh New Philosophical Journal, vol. xv. p. 123, from the Annuaire for the year 1833, that he entirely rejects the theory of the radiation of heat through a thick layer of water. In the same paper, although he does not, in conclusion, pretend to give a complete explanation of the phenomenon, he brings forward, as explanations in part, three circumstances, which, although accurately stated by him, appear to be not exclusively appropriate to ice formed at the bottom, and cannot therefore aid us in solving the main question which we have to discuss here, which I apprehend to be, Why is ice formed sometimes on the surface of running water, and sometimes at the bottom? On reading M. Arago’s paper, I became desirous of offering some remarks in an­swer to it, as without some one doing this, on proper data, a misapprehension con­cerning the cause of a natural phenomenon, so much at variance with our most fre­quent experience of the formation of ice only on the surface of all waters, as to have often greatly excited the attention and even called forth the astonishment of scientific men, would continue to be propagated under the authority of a distinguished name. Having, however, no record of my former observations to enable me to refer accu­rately to the time, place, and other circumstances of them, I delayed till a renewed occurrence of ice on the bottoms of our streams should enable me to repeat them.