Conceive yourself confronted by a pop-gun, some ten feet in diameter, charged with mephitic vapours and plugged with microbes of typhoid fever. Conceive your sensations when you were aware that the piston was being driven home. That was my situation in March, 1890, when I got a letter from Messrs. Allen asking me to go into Provence and Languedoc, and write them a book thereon. I dodged the microbe, and went.