The Collaborative International Dictionary
London smoke
London smoke \Lon"don smoke\ A neutral tint given to spectacles, shade glasses for optical instruments, etc., which reduces the intensity without materially changing the color of the transmitted light.
Usage examples of "london smoke".
As she made her way to the studio she selected a good brick wall, steeped in London smoke and moisture, and went and pressedher rump against it.
From the best districts, I pass through tiers of London smoke and shadow.
She was staying at Branford, either from neglect of the company or because the London smoke disagreed with her, and there Smith went to see her.