The Natural History of Selborne

Blue mist. Vulg. called London smoke. Quae: Does this meteorous appearance shew itself on the N:E. side of London when the wind is N:E? If that is the case then that mist cannot proceed from the smoke of the metropolis. This mist has a strong smell, & is supposed to occasion blights. When such mists appear they are usually followed by dry weather. They have somewhat the smell of coal-smoke & therefore are supposed to come from London as they always come to us with a N:E:wind.