Watch Your Step and Hold Your Breath

Thanks for the link, Jane. And if anybody wants to get a visual of the London Streets go to this website: http://charlesdickenspage.com. Then click on the "Dickens' London" link on the left side of the page, and scroll down to the "Old London Street Scenes" video. Although the film was shot in 1900,  the streets were much different during Dickens' day. Note the proliferation of horse manure in the streets and that the people don't even bother to look down as they zig zag across them. Based on 19th century reports, it's been calculated that during Dickens' day the streets of London collected 40,000 tons of manure annually, mostly from horses but also from cattle and sheep on their way to the meat markets. Where did all these animal droppings go? It was eventually pulverized into dust. If you recall the references to the dust in Tulkinghorn's office (see Chapter 25 and especially the beginning of  Chapter 22), he seems to have taken in one ton of it himself. Hold your breath, Mr. T. That's poop dust in your air.