Benjamin Franklin; Self-Revealed, Volume 2 (of 2) / A Biographical and Critical Study Based Mainly on his own Writings

by Wiliam Cabell Bruce

the expensive and intricate French fireplaces with hollow backs, hearths and jambs of iron; the Holland stove, which shut off the sight of the fire, and could not conveniently be used for any purposes except those of warmth; the German stove which was subject to very much the same disadvantages as the Holland stove; and charcoal fires in pots which emitted disagreeable and dangerous fumes and were used chiefly in the shops of handicraftsmen. From the shortcomings of all these methods of heating rooms, the Franklin stove, its inventor contended, was exempt. It diffused heat equally throughout a whole room; if you sat in an apartment warmed by it, you were not scorched before, while you were frozen behind; nor were you exposed to the drafts from which so many women, particularly, got colds in the head, rheums and defluxions that fell upon their jaws and gums, and destroyed early many a fine set of teeth in the northern colonies, and from which so many persons of both sexes contracted coughs, catarrhs, toothaches, fevers, pleurisies and other diseases. It kept a sick room supplied with a fresh and yet properly tempered flow of pure air. It conserved heat. It economized fuel. With it, Franklin said, he could make his room twice as warm as it used to be with a quarter of the wood that he used to consume. If you burned candles near it, they did not flare and run off into tallow as in the case of ordinary fireplaces with their excessive drafts. It corrected most smoky chimneys. It prevented all kinds of chimneys from fouling, and if they fouled made them less likely to fire, and, if they fired, made the fire easier to repress. A flame could be speedily kindled in it with the help of the shutter or trap-bellows that went along with it. A fire could be readily extinguished in it, or could be so secured in it that not one spark could fly out of it to do any damage. A room once warmed remained warm all night. "With all these Conveniences," concludes Franklin, "you do not lose the pleasing Sight nor Use of the Fire, as in the Dutch Stoves, but may boil the Tea-Kettle, warm the Flat-Irons, heat Heaters, keep warm a Dish of Victuals by setting it on the Top, &c. &c."

Some years after the publication of this essay, Franklin devised an improvement in the open chimney-place which tended to abate drafts and check the escape of heat up the chimney by contracting the chimney opening, bringing its breast down to within three feet of the hearth, and placing an iron frame just under this breast, with grooves on each side of the frame, in which an iron plate could be slid backwards and forwards at pleasure, for the purpose of cutting off the mouth of the chimney entirely from the chimney itself, when there was no fire on the hearth, or of leaving a space of not more than two inches for the escape of smoke between the further edge of the plate and the back of the chimney-mouth. This improved chimney-place was described by Franklin in letters to Alexander Dick and James Bowdoin. The letter to Bowdoin seems to leave little to be said on the subject of chimneys. It indicates that Franklin had subjected them to a scrutiny hardly less close than that which he had fixed upon the Leyden Jar. In connection with the currents and reverse currents, set up in them in summer by the relations of inequality, which the air in them sustains, at different hours of the day and night, to the outside temperature, he suggests that joints of meat might keep for a week or more during the hottest weather in chimney-openings, if well wrapt three or four fold in wet linen cloths, sprinkled once a day with water to prevent evaporation. Butter and milk in vessels and bottles covered with wet cloths might, he thought, be preserved in the same way. And he even thought, too, that the movements of air in chimneys might, with the aid of smoke-jack vanes, be applied to some mechanical purposes, where a small but pretty constant power only was needed. To appreciate how patiently and exhaustively Franklin was in the habit of pursuing every course of observation or reflection opened up by his scientific propensities, the whole of this letter, which had much more to say on the subject of chimneys than we have mentioned, should be read.

At a later period of his life, Franklin describes to Turgot what he called his new stove. The novel feature of this consisted of an aerial syphon by which the smoke from the fireplace of the stove was first drawn upwards through the longer leg of the syphon, and then downwards through its shorter leg, and over burning coals, by which it was kindled into flame and consumed.

The ingenuity of Franklin was also exerted very successfully in the rectification of smoky chimneys. In his essay on the causes and cure of such chimneys, written on his last ocean voyage, he resolved the causes into no less than nine heads, and stated with his accustomed perspicuity and precision the remedy for each cause. In his time, the art of properly carrying off smoke through chimneys was but imperfectly understood by ordinary builders and mechanics, and it was of too humble a nature to tempt discussion by such men of science as were capable of clearly expounding the physical principles upon which it rested. It was not strange, therefore, that Franklin, who deemed nothing, that was useful, to be beneath the dignity of philosophy, should have acquired in his time the reputation of being a kind of "universal smoke doctor" and should have been occasionally consulted by friends of his, such as Lord Kames, about refractory chimneys. The only smoky chimney, that seems to have completely baffled his investigation, recalls in a way the philosopher, who thought that he had discovered a new planet, but afterwards found that what he saw was only a fly in the end of his telescope. After exhausting every scientific resource in an effort to ascertain why the chimney in the country-house of one of his English friends smoked, Franklin was obliged to own the impotence for once of his skill; but, subsequently, his friend, who made no pretensions to the character of a fumist, climbed to the top of the funnel of his chimney by a ladder, and, on peering down into it, found that it had been filled by nesting birds with twigs and straw, cemented with clay, and lined with feathers.

Nor was the attention given by Franklin to ventilation by any means confined to chimneys. Air vitiated by human respiration also came in for a share of it. Describing an experiment by which he demonstrated the manner in which air affected in this way is purified, Alexander Small said:

The Doctor confirmed this by the following experiment. He breathed gently through a tube into a deep glass mug, so as to impregnate all the air in the mug with this quality. He then put a lighted bougie into the mug; and upon touching the air therein the flame was instantly extinguished; by frequently repeating the operation, the bougie gradually preserved its light longer in the mug, so as in a short time to retain it to the bottom of it; the air having totally lost the bad quality it had contracted from the breath blown into it.

Franklin became deeply interested in the brilliant course of investigation pursued by Priestley with respect to gases, and several penetrating glances of his into the relations of carbonic acid gas to vegetation have come down to us. Observing on a visit to Priestley the luxuriance of some mint growing in noxious air, he suggested to Priestley that "the air is mended by taking something from it, and not by adding to it." He hoped, he said in a letter to Priestley, that the nutriment derived by vegetation from carbonic acid gas would give some check to the rage of destroying trees that grew near houses, which had accompanied recent improvements in gardening from an opinion of their being unwholesome.

Just as he was consulted about the best methods of protecting St. Paul's Cathedral and the arsenals at Purfleet from lightning, so he was also consulted by the British Government as to the best method for ventilating the House of Commons. "The personal atmosphere surrounding the members," he thought, "might be carried off by making outlets in perpendicular parts of the seats, through which the air might be drawn off by ventilators, so placed, as to accomplish this without admitting any by the same channels." The experiment might be tried upon some of our City Councilmen. Principles of ventilation, expounded by Franklin, were also utilized by the Messrs. Adam of the Adelphi, in the construction of the large room built by them for the meetings of the Society for the Encouragement of Arts. We also find him suggesting openings, close to the ceilings of rooms, and communicating with flues, constructed alongside of chimney flues, as effective means for ventilating rooms.

With all his primary and secondary gifts for scientific research, it is difficult to believe that, if Franklin had not been diverted from it by engrossing political cares, he would have added both to his special reputation as a student of electricity and to his general reputation as a man of science. As it was, his civic activity and popular leadership in Pennsylvania, his several agencies abroad, his participation in the American Revolution, his career as Minister to France, and his official duties, after his return, made such imperious demands upon his time that he had little or no leisure left for scientific pursuits. This picture of his situation which he presented in a letter to Ingenhousz, when he was in France, was more or less true of almost every part of his life after he became famous:

Besides being harass'd with too much Business, I am expos'd to numberless Visits, some of Kindness and Civility, many of mere idle Curiosity, from Strangers of America & of different Parts of Europe, as well as the Inhabitants of the Provinces who come to Paris. These devour my Hours, and break my Attention, and at Night I often find myself fatigu'd without having done anything. Celebrity may for a while flatter one's Vanity, but its Effects are troublesome. I have begun to write two or three Things, which I wish to finish before I die; but I sometimes doubt the possibility.