Published online by Cambridge University Press: 15 May 2009
1. The rat population of a main sewer was studied by means of census baits.
2. In a series of poison treatments extending over 4–5 months all rats visiting the access points were eliminated.
3. At the end of this period the population was 40–65% of what it was at the beginning.
This work would not have been possible without the generous assistance once more of Mr A. R. J. Vickery, Assistant District Engineer of the Chief Engineer's Department of the London County Council and members of his staff, and without the ready co-operation of the Borough Engineer, the Medical Officer of Health and the Chief Health Inspector of the Metropolitan Borough of Bethnal Green, through which area the sewer ran.