One letter which we have received is of great importance, as it details the means by which an affected crop has been preserved. We think it our duty to make the following extract, premising that the writer is an eminent practical farmer in the south of Scotland:--"I had this year a large crop of potatoes, but my fields, like those of my neighbours, did not escape the epidemic. On its first appearance, I directed my serious attention to the means of preserving the crop. Though inclined to impute the complaint to a deeper cause than the wetness of the season, I conceived that damp would, as a matter of course, increase any tendency to decay, and I took my measures accordingly. Having raised my potatoes, I caused all the sound ones, which seemed free from spot and blemish, to be carefully picked by the hand; and, having selected a dry situation in an adjoining field, I desired them to be heaped there in quantities, none of which exceeded a couple of bolls. The method of pitting them was this:--On a dry foundation we placed a layer of potatoes, which we covered with sandy mould, though I don't doubt straw would do as well; above that, another layer, also covered; and so on, keeping the potatoes as separate from each other as possible. We then thatched and covered them over as usual with straw, leaving ventilators on the top. I have had them opened since, and there is no trace whatever of any decay, which I attribute to the above precautions, as others in the neighbourhood, whose potatoes grew in exactly similar soil, have lost great part of their crop by heaping them in huge masses. Ventilation, you may depend upon it, is a great preservative. I have, I think, arrested the complaint even in affected potatoes, by laying them out (not heaping them) on a dry floor, in a covered place where there is a strong current of air. They are not spoiling _now_; and when the unsound parts are cut out, we find them quite wholesome and fit for use. I am of opinion, therefore, that by using due caution, the progress of the complaint, so far as it has gone, may in most cases be effectually checked."