The Editor closed the discussion at this point by saying that the subject was not of sufficient agricultural importance to be continued further.

The following is my brother Richard Garnett’s [16] account of his observations on bottom-frosts. (The paper was written in 1818, and published in the “Journal of the Royal Institution.”)

* * * * *

ON THE PRODUCTION OF ICE AT THE BOTTOMS OF RIVERS.

The phenomenon of the production of ice at the bottoms of rivers has been repeatedly noticed, but I am not aware that any satisfactory solution of the cause has hitherto been given.  In Nicholson’s “Dictionary of Chemistry,” several different hypotheses are enumerated, which I shall not stop now to examine, since it may be safely asserted that they neither accord with the established principles of chemistry, nor with the facts for which they endeavour to account.  The most recent theory with which I am acquainted is that of Mr. A. Knight, who in a paper lately published in the “Philosophical Transactions,” seems to consider the particles of ice as originally formed at the surface, and afterwards absorbed by the eddies of streams to the bottom.  He states, in support of this idea, that he did not observe any similar phenomenon in still water.  I shall advert to this hypothesis in the sequel, and at present it may suffice to remark of it and all others which I have hitherto seen, that supposing any of them to be correct, the same effects ought regularly to be produced whenever the atmosphere is at a similar temperature, or in other words, that whenever the frost is so intense as materially to affect the water of a river, we may then expect to find ice at the bottom.  Now this is certainly not the case, since the appearance we are treating of never occurs but under peculiar atmospherical circumstances, and rivers are frequently frozen over, and remain so for a length of time without a particle of ice being visible at the bottom of their streams.  I do not now profess to have developed this mystery, but merely intend to state the circumstances under which the phenomenon takes place, as well as a few particulars connected with it, which are perhaps not generally known, and which may hereafter be serviceable as data for investigating the cause.

It is well known to meteorologists that a severe frost in winter does not always commence in a uniform manner.  Sometimes it begins with a gentle wind from the E. or N.E., and is at first comparatively mild in its operations, but afterwards gradually increases in intensity.  Frosts of this kind are generally more lasting than others, and during such, I have not observed that any ice is generated at the bottoms of streams; though the deep and still parts of rivers are often frozen over to a considerable extent.  At other times, during the continuance of the violent south-westerly gales which are so prevalent in this country in the winter months, the wind frequently shifts on a sudden