Impregnation of handkerchiefs, ultra-violet lighting, and other control methods in prevention of upper respiratory disease.

The total population of some 4,000 persons included at the relevant times between 1,200 and 1,800 young apprentices organized in three "Wings". Each of these wings had its own similar barrack and dining rooms (in permanent brick buildings), its own Service Institutes for use in leisure hours, and its own specially allotted sections of the large and airy workshops. Intermingling of the wings was, therefore, largely limited to open-air activities, with, to a smaller extent, some mixing off-duty and in a communal station cinema. The wings were themselves sub-divided into three "Squadrons", and these too, were fairly self-contained and separate units, though not so decisively separated as the wings. In general, this structure, coupled with a highly organized medical service and method of sicknesA recording, made it administratively possible, and indeed simple, to set up "experimental" groups to be compared with "control" groups, both groups being very similar in their characteristics and conditions of life, but living and working largely apart.