We therefore carefully watched .
We therefore carefully studied these 75 men for three or four days , at the end of which time we had picked out four men who appeared to be physically able to handle pig iron at the rate of 47 tons per day .
We therefore carefully watched and studied these 75 men for three or four days , at the end of which time we had picked out four men who appeared to be physically able to handle pig iron at the rate of 47 tons per day .