House near London. His best Room had a Chimney, in which he told me he never could have a Fire, for all the Smoke came out into the Room. I flatter'd myself I could easily find the Cause, and prescribe the Cure. I had a Fire made there, and found it as he said. I opened the Door, and perceived it was not want of Air. I made a temporary Contraction of the Opening of the Chimney, and found that it was not its being too large, that caus'd the Smoke to issue. I went out and look'd up at the Top of the Chimney; its Funnel was join'd in the same Stack with others, some of them shorter, that drew very well, and I saw nothing to prevent its doing the same. In fine, after every other Examination I could think of, I was oblig'd to own the Insufficiency of my Skill. But my friend, who made no Pretension to such kind of Knowledge, afterwards discover'd the Cause himself. He got to the Top of the Funnel by a Ladder, and looking down, found it filled with Twiggs and Straw cemented by Earth, and lin'd with Feathers. It seems the House, after being built, had stood empty some Years before he occupy'd it; and he concluded, that some large Birds had taken the Advantage of its retired Situation to make their Nest there. The Rubbish, considerable in Quantity, being removed, and the Funnel cleared, the Chimney drew well, and gave Satisfaction.

In general, Smoke is a very tractable Thing, easily governed and directed when one knows the Principles, and is well informed of the Circumstances. You know I made it descend in my Pennsylvania Stove. I formerly had a more simple Construction, in which the same Effect was produc'd, but visible to the eye (Plate, Figure 7). It was compos'd of two plates, A B and C D, plac'd as in the figure. The lower

plate A B, rested with its Edge in the Angle made by the Hearth with the Back of the Chimney. The upper Plate was fix'd to the Breast, and lapt over the lower about 6 Inches, leaving a space of 4 Inches wide and the length of the Plates (near 2 feet) between them. Every other Passage of Air into the Funnel was well stopt. When therefore a Fire was made at E, for the first time with Charcoal, till the Air in the Funnel was a little heated thro' the Plates, and then Wood laid on, the Smoke would rise to A, turn over the Edge of that Plate, descend to D, then turn under the Edge of the upper Plate, and go up the Chimney. It was pretty to see, but of no great Use. Placing therefore the under Plate in a higher Situation, I remov'd the upper plate C D, and placed it perpendicularly (Plate, Fig. 8), so that the upper Edge of the lower Plate A B came within about 3 Inches of it, and might be push'd further from it, or suffer'd to come nearer to it, by a moveable Wedge between them. The Flame then ascending from the Fire at E, was carried to strike the upper Plate, made it very hot, and its Heat rose and spread with the rarefied Air into the Room.

I believe you have seen in use with me the Contrivance of a Sliding Plate over the Fire, seemingly plac'd to oppose the rising of the Smoke, leaving but a small Passage for it, between the Edge of the Plate and the Back of the Chimney. It is particularly describ'd, and its Uses explain'd, in my former printed Letter, and I mention it here only as another instance of the Tractability of Smoke.

What is called the Staffordshire Chimney, affords an Example of the same kind. The Opening of the Chimney is brick'd up even with the Fore Edge of its Jambs, leaving open only a Passage over the Grate of the same

width, and perhaps 8 Inches high. The Grate consists of semicircular Bars, their upper Bar of the greatest Diameter, the others under it smaller and smaller, so that it has the Appearance of half a round Basket. It is, with the Coals it contains, wholly without the Wall that shuts up the Chimney, yet the Smoke bends and enters the Passage above it, the Draft being strong, because no Air can enter that is not obliged to pass near or through the Fire, so that all that the Funnel is fill'd with is much heated, and of course much rarefied.

Much more of the Prosperity of a Winter Country depends on the Plenty and Cheapness of Fuel, than is generally imagined. In Travelling I have observed, that in those Parts where the Inhabitants can have neither Wood, nor Coal, nor Turf, but at excessive Prices, the Working People live in miserable Hovels, are ragged, and have nothing comfortable about them. But when Fuel is cheap (or where they have the Art of managing it to Advantage), they are well furnish'd with Necessaries, and have decent Habitations. The obvious Reason is, that the Working Hours of such People are the profitable Hours, and they who cannot afford sufficient Fuel have fewer such Hours in the 24, than those who have it cheap and plenty: For much of the domestic Work of poor Women, such as Spinning, Sewing, Knitting; and of the Men, in those Manufactures that require little bodily Exercise, cannot well be perform'd where the Fingers are numb'd with Cold. Those People, therefore, in cold Weather, are induc'd to go to bed sooner, and lie longer in a Morning, than they would do, if they could have good Fires or warm Stoves to sit by; and their Hours of Work are not sufficient to produce the Means of Comfortable

Subsistence. Those public Works, therefore, such as Roads, Canals, &c., by which Fuel may be brought cheap into such Countries from distant Places, are of great Utility; and those who promote them may be reckoned among the Benefactors of Mankind.

I have great Pleasure in having thus comply'd with your Request, and in the Reflection, that the Friendship you honour me with, and in which I have ever been so happy, has continued so many Years without the smallest Interruption. Our Distance from each other is now augmented, and Nature must soon put an End to the possibility of my continuing our Correspondence; but, if Consciousness and Memory remain in a future State, my Esteem and Respect for you, my dear Friend, will be everlasting.

B. FRANKLIN.

Notes to the Letter upon Chimneys

No. I

The latest work on architecture, that I have seen, is that entitled Nutshells, which appears to be written by a very ingenious man, and contains a table of the proportions of the openings of chimneys; but they relate solely to the proportions he gives his rooms, without the smallest regard to the funnels. And he remarks, respecting those proportions, that they are similar to the harmonic divisions of a monochord.' He does not indeed lay much stress on this; but it

1 "It may be just remarked here, that upon comparing these proportions with those arising from the common divisions of the monochord, it happens, that the first answers to unisons; and, although the second is a discord, the third answers to the third minor, the fourth to the third major, the fifth to the fourth, the sixth to the fifth, and the seventh to the octave.” — Nutshells, page 85.-ED.

shows that we like the appearance of principles; and where we have not true ones, we have some satisfaction in producing such as are imaginary.

No. II

The description of the sliding plates here promised, and which have been since brought into use under various names, with some immaterial changes, is contained in a former letter to James Bowdoin.

1599. DESCRIPTION OF A NEW STOVE FOR OF PITCOAL, AND CONSUMING

BURNING

ALL ITS SMOKE.1

TOWARDS the end of the last century an ingenious French philosopher, whose name I am sorry I cannot recollect, exhibited an experiment to show that very offensive things might be burnt in the middle of a chamber, such as woollen rags, feathers, &c., without creating the least smoke or smell. The machine in which the experiment was made, if I remember right, was of this form, (Plate XV. Fig. 1,) made of plate iron. Some clear burning charcoals were put into the opening of the short tube A, and supported there by the grate B. The air, as soon as the tubes grew warm, would ascend in the longer leg C and go out at D, consequently air must enter at A descending to B. In this course it must be heated by the burning coals through which it passed, and rise more forcibly in the longer tube, in propor

II:

1 From Transactions of The American Philosophical Society (Old Series)

: 57. It was read at a meeting of the Society, January 28, 1786. — Ed.