... throat, and inclined the jambs. See coving. In 1745, Dr. Benjamin Franklin introduced a fireplace which he named the Pennsylvanian, in which Prince Rupert's descending flue was combined with Polignac 's caliducts. This is shown at F. (Fig. 1997.) Count Rumford's improvements consisted mainly in the contraction of the chimney at the throat, the rounding of the breast-work, and the flaring of ...