"The great fault of all the open Fire-places, or Chimnies, for burning... an open fire, now in common use, is, that they are much too large; or rather it is the throat of the Chimney or the lower part of its open canal, in the neighbourhood of the mantle, and immediately over the fire, which is too large. This opening has hitherto been left larger than otherwise it probably would have been made, in order to give a passage to the Chimney-sweeper; but I shall show... how a passage for the Chimney-sweeper may be contrived without leaving the throat of the Chimney of such enormous dimensions as to swallow up and devour all the warm air of the room, instead of merely giving a passage to the smoke and heated vapour which rise from the fire, for which last purpose alone it ought to be destined."