supercharged with coal smoke, with minute carbonaceous particles, “grits” and “smuts,” with certain heavy gases, and with a vast number of other impurities. It was chiefly the result of the huge and reckless consumption of coal carried on over the wide-extending city, the smoke from which, not being re-consumed or filtered off in any way, was caught up and retained by the vapour-laden air. The fog was the most disagreeable and dangerous of all the climatic sufferings that Londoners had to bear. It filled the nostrils and air-passages of those who breathed it with soot, and choked their throats and lungs with black, gritty particles, causing illness and often death to the aged, weakly, and ailing; it also caused headaches, and oppression, and all the symptoms that tell of the respiration of vitiated air. Londoners were well accustomed to the inconvenience of these fogs, and looked upon them in the light of a regular institution, not caring to investigate their cause with a view to some means of mitigating them. The fog in the city had been known from time immemorial, especially in those districts lying near to the river, or to localities that had originally been marshes; but it was only of late years that the recurrence of fogs during autumn, winter, and spring, had assumed such alarming proportions. Even twenty years before the period I am writing of, the fog was seldom so thick and foul in character, or it was so only over very limited areas; while if it continued for more than a few hours at a time, that was considered a fact to be severely commented upon. But the plague had increased in severity of late—so much so, that its density turned day into night, and clothed night in impenetrable obscurity; its extent was greater, involving all the districts between Hampstead and the Surrey hills,
