H. H. Windsor, Mission Furniture: How to Make It…
“ The hole will permit the water of condensation to escape. Steam should not escape from the box when a charge of wood is being softened. Steam which escapes from the box in the form of vapor has done no work whatever, and is just so much waste of fuel. In order to give up its heat to the wood, the steam must condense and come away from the box as water. Therefore, in steaming a charge of pieces in the box, never crowd the teakettle so hard that the steam escapes around the heads of the box or through any other joints. ”
