No. 116: Mar-Apr 1998
June 1783. Much of Europe.
"...the atmosphere was suddenly invaded, in Europe, by a sort of dry fog of peculiar character. It did not moisten objects, did not affect the hygrometer, and persisted when the wind rose, and rain fell. The sun looked pale through it. This fog lasted a month. One curious point is, that it was phosphorescent, and gave a light like moonlight at night."
August 18, 1821. Western Europe.
"...a similar fog was observed throughout Western Europe; it lasted twelve days. It deprived the sun of so much brightness, that one could look at this star at any hour; it gave the disc a glossy blue tint. Twilight assumed an extraordinary brightness, so that the day was greatly prolonged, and one could even read at midnight."
(Houzeau, M.; "On Certain Enigmas of Astronomy," English Mechanic, 29:32, 1879.)