DARK DAY. Any day in which the sun light appears to be remarkably dim or altogether absent. In New England the term is specifically applied to Slay 19, 17S0. also known as Black Friday: but many similar dark days are also on record in other parts of the world. Other notable dark days in the United States were those of October 21. 1716. and October 19, 1762. darkness often prevails during erup• t.ions of ashes from volcanoes. In recent years the months of August and September. I881, were remarkable in the eastern part of the United States for a long series of days in which arti ficial light was oftentimes necessary at mid day and business was generally very much in terrupted. In this case the darkness is known to have been the result of a combination of ordi nary cloudiness with the smoke from forest and prairie fire, and it is presumable that the same conditions must have obtained during the his torical dark days of the previous century. The rnited Stales Monthly Weather Review, for Sep tember, 1881. page 27, says: "The foggy or smoky condition of the atmosphere became quite general from the first to the tenth of this month over that portion of the United States between the meridians of 67° and 87° W. and the parallels of 40° and 45° N. It reached an un usual culmination in density in the eastern por tion of the Middle Atlantic States and through out New England, where it interrupted the prosecution of business and compelled the use of artificial light. The destructive violence of prairie and forest fires throughout northern Michigan and portions of Canada has perhaps never been exceeded, and the intensity of the ac companying smoke was simply dreadful. On
September 6 southwesterly winds prevailed from Tennessee northward to Lake Superior, and thence eastward to the Canadian maritime prov inces, and smoke was reported as far south as Knoxville. westward to Milwaukee, northward to Rockliffe. Canada, and eastward to New Brunswick. To show the progress eastward of this condition in the atmosphere it is necessary to trace the movement of low-pressure areas over Canada and northern New England, and watch the accompanying change in wind direc tions." The darkness of the dark day of May, 1780. covered very much the same area, with southwest winds and occasional light rains, and was undoubtedly of the saute nature, although in both cases it was attributed by the supersti tious to supernatural causes. On the plains of Tibet, according to Marco Polo and other trav elers. dark days are sometimes caused by clouds of dust so fine and light that it is carried to a great distance by the wind. Similar days of darkness have been caused by clouds of mingled vapor, smoke, and dust emanating from volcanic eruptions, although such clouds do not usually extend to the great distances reached by clouds of smoke from forest tires. Cases of such vol canic clouds occurred in connection with the eruption of Mont Pelee and La Soufriere in the West Indies in May, 1902.