"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."
A fireplace or hearth is a structure made of brick, stone or metal designed to contain a fire. Fireplaces are used for the relaxing ambiance they create and for heating a room. Modern fireplaces vary in heat efficiency, depending on the design.
"At the same time, the air, warmed under the bottom plate and in the air-box, rises and comes out of the holes in the side plates, very swiftly, if the door of the room be shut, and joins its current with the stream before mentioned, rising from the side, back, and top plates."
"We leave it to the political arithmetician to compute how much money will be saved to a country, by its spending two thirds less of fuel; how much labor saved in cutting and carriage of it; how much more land may be cleared by cultivation; how great the profit by the additional quantity of work done, in those trades particularly that do not exercise the body so much, but that the workfolks are obliged to run frequently to the fire to warm themselves; and to physicians to say, how much healthier thick-built towns and cities will be, now half suffocated with sulphury smoke, when so much less of that smoke shall be made, and the air breathed by the inhabitants be consequently so much purer."
"It is to be observed, that the entering air will not be warm at first lighting the fire, but heats gradually as the fire increases."
"[T]he builder of chimneys has been left to grope his way in the dark without assistant; and in almost every instance his attempts to improve upon the practice of his predecessors, have been unsuccessful; so that the inhabitants of these countries, with justice, complain that the inconveniencies felt in new houses from this cause, usually are more than sufficient to counterbalance all the elegancies that modern refinement has introduced into the dwellings..."
"The earth is every where surrounded with a great body of air, that is called the atmosphere. This air is a thin elastic fluid, possessing some qualities peculiar to itself, but subjected in general to the same physical laws with other fluids; and of consequence it hath a constant tendency to preserve an exact equilibrium in all its parts; so that if at any time the weight of it at one place is diminished, the heavier air rushes from all sides towards that point, till the equilibrium be again restored."
"The air of the room, warmed behind the back plate, and by the sides, front, and top plates, becoming specifically lighter than the other air in the room, is obliged to rise; but the closure over the fire place hindering it from going up the chimney, it is forced out into the room, rises by the mantel-piece to the ceiling, and spreads all over the top of the room, whence being crowded down gradually by the stream of newly-warmed air that follows and rises above it, the whole room becomes in a short time equally warmed."