All the evidence is that punishing the hands is dangerous. Almost inevitably therefore the bottom will have to be the target. I suggest a micrometer device to measure the thickness of the outer clothing and a carefully graduated equivalence table involving different weights of cane and numbers of strokes. Assumptions will of course have to be made when incorporating the adjustment factor for underwear, but at least this should encourage common sense in that contentious area on the part of pupils, especially female pupils!