Questionnaire survey of the drift mines of the British Isles revealed that the presence or absence of rat infestations could be related to the size of the mine in terms of manpower, large mines being more commonly infested than small ones. In addition, various features of drift mines and their surroundings, i.e. the presence of urban areas, nearby rat concentration points, canteen and surface stables, horses, the absence of buildings and the type of surface sanitation are all related to infestation. Field survey has shown that the extent of dilapidation and piling of waste material assists infestation. It has also indicated that the greater infestation of pits with large numbers of workmen is due to some extent to the extra cover provided by the greater number of surface buildings, these being few or lacking altogether in small pits.

At a mine at which changes in the rat population were studied it was seen that unsuccessful poisoning could leave a breeding nucleus of rats, but that there could also be a speedy re-invasion even after successful poison treatments. Whilst the surface rat population in the buildings of this mine was controlled there were no underground infestations. It appears, therefore, that regular inspection and control of surface infestations should in most cases prevent underground infestation.

This work was carried out under a research grant from Safety in Mines Research Establishment, Ministry of Power, and I am indebted to the Ministry for permission to publish the results. I should like to express my gratitude to the several members of the staff of the Safety in Mines Research Establishment, Sheffield, for the help they gave, in particular Mr C. S. W. Grice. I should like also to thank Prof. L. E. S. Eastham in whose department the work was carried out, Dr E. T. B. Francis who supervised it, Miss B. B. Jones of the Ministry of Agriculture, Fisheries and Food, and the many employees of the National Coal Board who assisted at various times.