"What proportion does the radiant heat bear to the combined heat? ...[T]he quantity of heat which goes off combined with the smoke, vapour, and heated air is much more considerable, perhaps three or four times greater... And yet, small as the quantity is of... radiant heat, it is the only part... ever employed... in heating a room. The whole of the combined heat escapes by the Chimney, and is totally lost; and... no part of it could ever be brought into a room from an open Fire-place, without bringing along... the smoke..."