"Dr. Franklin, in 1785, published "Observations on the Cause and Cure of Smoky Chimneys." He has very satisfactorily explained all the usual causes of this defect, and shown their remedies. To this pamphlet succeeded the "Essay" of Count Rumford, in 1796, whose improvements in the construction of fire-places have been very generally adopted. These two works together, form a valuable body of information. They are well known to the public, but it is not so generally known, that exactly a hundred years ago, viz. in the year 1715, Dr. Desagulier published his book, entitled "Fires Improved, being a new method of Building Chimneys, so as to prevent their smoking, &c." which is a translation of a still older work from the French of M. Gauger, which shows that the most, if not all, the principles pointed out by Count Rumford were understood, and are explained by M. Gauger. He also proposed seven different constructions of chimneys, in which there are hollow cavities made by iron plates in the back[,] jambs and hearth, through which plates the heat passing warms the air in those cavities, which is continually coming into the room fresh and warm. This construction had many obvious advantages; but the expense and difficulty attending it, at that early period, discouraged the propagation of the invention. In our own times, however, similar constructions have been brought forward as new, probably without the knowledge of what had been done so long before, and therefore with all the merit of invention."