BENEATH London, as beneath other great cities, lies a queer UnderWorld of mysterious tunnels full of noxious gases, unfragrant liquids and enormous rats. The ordinary person hears of these sewers only on the rare occasions when the sewer gas breaks out, but there are men whose working hours are spent entirely amongst them. In this evening's talk Mr... Palmer will describe a. day's work—or, more likely, a night's work-in this strange field.