The blight of 1846 was identical with that of 1845, but more rapid and universal.  The leaves of the potato plant were spotted in the same way; the stalk itself soon became discoloured—­not completely, but in rings or patches; it got cankered through at those places, and would break short across at them like rotten wood.  Moisture, it was observed, either brought on or increased the blight, yet the rainfall of 1846 rose very little above the average of other years; probably not more than from two to three inches; but the rain fell very irregularly, being most copious at those times when it was likely to do most injury to the crops.  The Spring was harsh and severe; snow, hail and sleet fell in March; at Belfast, there was frost and snow even in the first week of April.  In contrast with this, the greater part of June was exceedingly warm, which must have stimulated vegetation to an unnatural degree, thus exposing the growing crops all the surer to danger, whenever the temperature should fall.  It fell suddenly and decidedly, and the month closed with thunderstorms and heavy rains.  On the 19th, it was reported that the weather at Limerick underwent a sudden change from tropical heat to copious rain, with thunder, and lightning, followed by intense cold—­there were hail showers on the 24th.  St. Swithin, true to his traditional love of moisture, ushered in his feast, the 15th of July, with a downpour of rain, and next day a fearful thunderstorm broke over Dublin, followed by a deluge of rain.  The same sort of weather prevailed in almost every part of the country throughout July and August.

On the evening of the 3rd of the latter month, Mr. Cooper, of Markree Castle, observed a most singular cloud, which extended itself over the east of the range called the Ox Mountains, in the County Sligo, accurately imitating, in shape, a higher range of mountains somewhat more distant; afterwards an extremely white vapour, resembling a snow-storm, appeared along the southern declivity of the range.  Mr. Cooper remarked to a friend at the time, that he thought this vapour might be charged with the fluid causing the disease in the potato.  The friend to whom this observation was made, being a resident near those mountains, Mr. Cooper requested him to make enquiries on the subject.  He afterwards informed him that on the same evening, or night, the blight fell upon the whole of that side of the mountain, where they had witnessed the strange appearance.  It was noticed in various districts, that some days before the disease appeared on the potatoes, a dense cloud, resembling a thick fog, overspread the entire country, but differing from a common fog in being dry instead of moist, and in having, in almost every instance, a disagreeable odour.  It is worthy of remark that from observations made by Mr. Cooper for a series of years, the average number of fogs for each year was a fraction under four,—­the night fogs for each year not being quite two.  In the year 1846, the night fogs were ten, the day two, being a striking increase of night fogs, in the year of greatest potato blight in Ireland.[114]