by Nick Bunker
As coastal Pennsylvania began to fill with people, and firewood grew scarce—as it had in 1741—this last defect in an English fire became all the more irksome. And so, with the help of science culled from his reading, Franklin tried to solve all these problems simultaneously, by exploiting the properties of hot iron and hot air. Iron, he knew, was slow to warm up, but once it did so it retained its temperature far longer than other substances, and it sent out heat in all directions. Better still, iron did so cleanly, with no fumes, no smell, and no detritus. As for the properties of air, Franklin could find them described in his textbooks, written by Sir Isaac Newton’s disciples.
Air, the books told him, was an “elastic fluid,” consisting of tiny particles. When heat was applied to a body of air, these little globes expanded in diameter, so that the air became “rarified” or “distended.” If the number of particles remained the same, but the space they occupied grew larger, then the weight of the air must fall: and so, in a kitchen or a parlor, hot air will always tend to rise toward the ceiling. Or as Franklin put it in his fireplace essay: “Air rarified and distended by heat, is specifically lighter than it was before, and will rise in other air…till it either comes to air of equal weight, or is by cold reduc’d to its former density.”
So iron made a splendid radiator, while—with a little ingenuity, and some skillful engineering—currents of air could be made to flow around a room. In 1709, one Nicolas Gauger, a Frenchman, had brought out a book titled The Mechanics of Fire—which Franklin had read—describing how he used these principles to build his own new fireplace. Its iron frame contained hidden cavities, filled with hot air, with slits at the top to allow it to escape. Franklin took the same idea and developed it into a far more ambitious device.
At the center of his fireplace, above the hearth where the fuel was set alight to warm the iron frame, there stood the essential component: the “air box.” A vertical compartment, it contained a system of internal ledges creating what Franklin called “winding passages,” to maximize the surface area of metal and therefore the heat it would conduct. At the bottom of the air box, there was a hole that communicated with a long tube or channel sealed into the brickwork beneath the floor of the room.
From outside the house, a continuous stream of fresh, cold air flowed through the channel and entered the air box. As it was warmed by the hot iron, so it spiraled upward through the winding passages until it entered the room through an opening at the top. This feature of the fireplace required precision casting by the iron founder. The plates would have to fit tightly together to stop the hot air leaking out through the joints. Meanwhile the smoke from the fire rose over the air box, and passed down behind it, to be fed into another, separate channel sealed beneath the brickwork. The smoke flowed along this second channel, and then rose up a funnel set into the wall behind the fireplace. From there it disappeared into the chimney, which was shut off from the room by an iron lid that could be opened for the chimney to be swept.
Perhaps the only surviving example of an original Franklin fireplace from the 1740s, albeit damaged and missing a key component, the air box. The fireplace was found in 1911 by the architect and historian Henry Chapman Mercer in a farmhouse in Montgomery County, Pennsylvania. From the collection of the Mercer Museum of the Bucks County Historical Society
It was a heating system that seemed to have everything: a cheerful fire in the hearth, iron as a radiator, and a stream of warm but fresh, clean air to heat each corner of the room and clear away the fug from human beings. None of the heat would vanish up the chimney. Alas, the early models of the fireplace failed to go according to plan—it was hard to get the outer air into the air box, unless the fire in the grate was very hot indeed, and the smoke tended to back up into the room—but it was the concept that counted.29
Franklin was thinking like a physicist. From the treatises in the Library Company collection, he had taught himself the language of science and gradually mastered its subtleties. “Rarified air,” for example: that was a phrase Sir Isaac had used in the 1680s in his masterpiece, the Principia. Although it seems that Franklin never studied the book in detail, he knew its contents from later works by the Dutchmen ’s Gravesande and Herman Boerhaave and their London translator, John Theophilus Desaguliers, all three of whom he deeply admired. Followers of Newton, they had tried to extend Sir Isaac’s theories to encompass the phenomena of heatas well as those of motion, gravity, and light.
Perhaps as early as 1732, inspired by an experiment by Boerhaave, Franklin had begun to think about the puzzles of heat. On a patch of snow, he placed pieces of cloth, colored black and white, and red and blue and yellow. It was a procedure that came naturally to Franklin, coming as he did from a family of dyers. As the sun shone down, he saw that the snow melted at different speeds beneath the different shreds of fabric. The white cloth kept the sun at bay, so that the snow beneath it did not melt. Meanwhile the darker shades absorbed the solar heat and passed it on, turning the snow into slush. It was a crude exercise, and the concepts at Franklin’s disposal were too vague to tell him what it meant. In 1737, his Junto friend Joseph Breintnall repeated the experiment, with the same results, and also came away unable to explain them.30
One solution might be this: that heat and light were really something else, a substance—or perhaps a fluid—which the Dutch Newtonians called Fire. “The intimate nature of Fire is unknown,” wrote ’s Gravesande, “but wherever we find Heat and Light, we say that there is what we call Fire.” Somehow this mysterious fluid, infinitely subtle and elastic, and moving at immensely high speed, could penetrate solid bodies. As it did so, it produced effects that varied according to the density of the tiny particles of which those bodies were composed. From the language of Franklin’s essay, it is clear that when he built the fireplace he was thinking about heat and light in just such a way.31
Odd though these ideas might seem today, they served a fruitful purpose: they also set people thinking about electricity. Three decades earlier at the Royal Society, with Sir Isaac Newton in the chair, it had been seen that if a glass sphere was spun around at high speed with a pad of leather pressed against it, flashes of light could be produced inside the glass. Newton’s assistant, Francis Hauksbee, showed that the glass would attract or repel filaments of brass or copper. Later, other scientists discovered that if the glass was rubbed for long enough, and an iron rod or a finger were placed nearby, a spark could be made to jump across the gap between them.
In the mid-1730s, chiefly in London and Paris, experiments such as this were repeated, refined, and taken much further. By attaching the iron rod to a long line of thread, the effects of electricity could be transmitted for a distance of more than two miles, with sparks appearing at the end of the line. What did this mean? As yet, no one could say; but there was a hypothesis that became ever more attractive.
As early as 1712, Newton had begun to speculate about something he called “an electric spirit,” “exceedingly active,” which permeated every particle of matter, gluing the atoms together. Not only that: having seen Hauksbee’s experiments, Newton wondered if perhaps this “very subtle potent active elastic spirit” might also account for the behavior of light—its emission, reflection, and refraction—to which he had devoted many years of research.32
In the decade after Newton’s death, the questions he had posed continued to fascinate his followers. Light and heat, the baffling sparks and flashes produced by Hauksbee and other researchers, Newton’s “electric spirit,” and the mysterious substance the Dutch knew as “Fire”: somehow they were all connected. If the connections could be understood, then the deepest secrets of the cosmos would be laid bare. Or so it appeared to the era’s most brilliant minds, including in the colonies Franklin’s friend and mentor James Logan.
Via his Quaker friends in England, Logan kept abreast of the latest research. In 1737 he completed the writing of a treatise of his
own, in which he hoped to create a synthesis of moral philosophy and the most advanced scientific learning. Never published in his lifetime—not until the twenty-first century, in fact—the book bore the very eighteenth-century title Of the Duties of Man as may be deduced from Nature. Parts of it he shared with Franklin, seeking his comments on the chapter that strove to define moral virtue. In passing, Logan also touched on electricity.
In the past, he wrote, its curious effects had been regarded as merely “a trifling appearance in nature.” But when he studied Hauksbee’s findings and the experiments of the 1730s, Logan began to wonder if perhaps the study of electricity held the key to what he called “more just and extensive notions…of the world we live in.” Steeped in the work of Newton, he knew that late in life Sir Isaac had been moving in the same direction. Even so, it was still a bold statement for Logan to make.33
His comments were all the more significant because he was writing on the edge of the wilderness, in a colony still thought of in England as little more than a source of pork and grain and a destination for felons or indentured laborers. But the fact was that by now—with its iron foundries, its craftsmen, and its Library Company—the colony had the makings of a scientific culture, with James Logan as its guiding light. Infirm or even crippled though he was, Logan could still write and think with the utmost clarity, and the questions that exercised his brain—and Franklin’s—were the same as those that baffled scientists in Europe. With his fireplace, his reading, and his fascination with heat, Franklin was already working in parallel with the best minds in Paris and London.
A case in point was a French aristocrat whose background could not have been more different. She was a woman of ingenuity—Émilie, Marquise du Châtelet—who took as her lover the philosopher Voltaire. In that same year of 1737, as Logan was finishing his magnum opus, the marquise and Voltaire retreated for the summer to her château by the Marne, there to enjoy intimate moments and to ponder the mysteries of physics. Like Franklin, they read the Dutch Newtonians. At a blacksmith’s forge, she and Voltaire heated rods of iron. Like Franklin they tried to understand the properties of “Fire.” By the end of the year, Madame du Châtelet had written a dissertation on the subject, to be published in 1739.34
With eloquence and poetry, the marquise expressed ideas identical to Logan’s. It seemed that behind the phenomena of heat and light, there lay what she called a “universal agent” that kept the cosmos in motion. It was, she wrote, “the breath of life that God has spread throughout his handiwork.” Madame du Châtelet knew the best electricians in Paris, and in their work she saw what she called “new miracles of nature.” She longed for the day when an “ingenious philosopher” would find the path that led to the center of the maze.
*1 The Pennsylvania Gazette often devoted much of its front page to diplomatic news from Europe.
*2 Indeed, an item from Franklin’s shop accounts suggests that Franklin might have acquired his first slave as early as 1735. An entry from that year, dated December 16, refers to Franklin buying a pair of shoes for a “negro boy.” Not until the 1990s, when Professor David Waldstreicher examined the accounts at the American Philosophical Society, did this detail come to the attention of historians.
*3 An Account of the New Invented Pennsylvanian Fire-Places.
Part Five
THE DAWN OF AMERICAN SCIENCE
Chapter Seventeen
A CHANGE OF LIFE
At the end of 1742, as Franklin approached the age of thirty-seven, his neighbors beheld a sound, successful man who made the best of every opportunity. He had just created another printing partnership—this time it was in New York with a former employee, James Parker—and Franklin had even published a novel. The first to be printed in America, it was a pirated edition of Volume I of Samuel Richardson’s Pamela. Readers must have found this rather frustrating, because they had to wait two more years for Franklin to give them the end of the story. But he had been very busy.
Although the economy was in the doldrums as the war continued and the West Indian trade fell away, Franklin had found a wealthy new client to keep him occupied. He had become the printer of choice for Count Nicolaus Ludwig von Zinzendorf und Pottendorf, a missionary from the German fatherland. The count was known for short as “Brother Ludwig.” A Moravian Christian, and a friend of John Wesley, he conceived the bold idea of unifying all the German sects in Pennsylvania: a notion that failed to appeal to the Amish, the Mennonites, the Dunkers, and the Schwenkfelders, to name but four of the denominations. Also taking umbrage were the Lutherans. From Germany they imported their own evangelist to do battle with Brother Ludwig.1
Once again Franklin found that he could make a profit from religious strife. In 1742 the count asked him to print no fewer than sixteen books and pamphlets in German. With so much work on hand, Franklin became more deeply involved in the making of paper as well. In the fall of that year, he formed a new alliance in the South, helping a printer from Williamsburg build a mill in Virginia, using rags that Franklin sent from Philadelphia.
And then, in November, at last his old enemy passed away. The death of Andrew Bradford at the age of fifty-six left Franklin in full command of the printing and publishing trade in the Delaware valley. Indeed with his network of partners along the coast, he was now the dominant force in printing in America as a whole. Even so Franklin could not feel secure. Far from it: like almost every businessman in the eighteenth century, especially in the colonies, he knew that his success was precarious. So was his status in society.
It was an age when the high road to distinction lay by way of real estate. And here Franklin had yet to make a permanent mark. He had acquired two properties—a three-acre field, perhaps for young William to graze his pony, and a vacant building plot in Philadephia—but these were tiny transactions compared to the vast deals done by the Pennsylvania Hamiltons or by William Allen. By the middle of the 1740s, Franklin would be comfortably off, but even by the American standards of the period he would never be truly rich. Cautious by nature, and jealous of his reputation, he did not smuggle Spanish rum or molasses. Nor did he speculate in tobacco, Carolina rice, or slaves or stolen Indian territory or contracts for the British military. Although Franklin was solid, he was not yet a guaranteed survivor.2
Following a path that resembled that of his old London colleague Charles Ackers, Franklin had created a mixed portfolio of businesses, grounded in the printer’s art. Poor Richard, the Gazette, the German tracts, paper money, and his postmastership: put them all together with the ventures in Charleston and New York and his clerkship of the Pennsylvania assembly, and Franklin had done very well. But had he done enough? He had made some brilliant maneuvers. Perhaps the shrewdest was his alliance with the new papermakers of Wissahickon, which was essential for his success in printing. Even so Franklin could not be sure that he and Deborah would enjoy a comfortable old age.
For the time being their marriage was sound, but what passion there was had faded away. At about this time Franklin composed a poetic tribute to Deborah. It was a ballad apparently written to mark their twelfth wedding anniversary, in which he called her “my plain country Joan.” She was “the joy of my life,” he wrote, “a companion delightful and dear,” tender and supportive, a good housekeeper and a welcoming hostess to his friends. She “could not be a better wife, might be a worse.” In short, she was “lovely old Joan.” Besides romantic ardor, something else was missing, and that was motherhood. Since Franky’s death, Deborah had been childless. For an entrepreneur in the eighteenth century this was a catastrophe in waiting. Of course they had William, but one son was rarely enough; and in any case, the boy did not aspire to be a printer, any more than the teenage Franklin had wanted to boil fat to make soap and candles. But without a successor, Franklin could never retire to devote himself to public service: and his accomplishments would die with him.3
That very fate had overtaken his clever unc
le Thomas in England, whose death without a son had doomed the Ecton Franklins to extinction. In colonial America, the problem was all the more acute. With no banks and no bond market, there was no one to sell Franklin an annuity to serve as a pension, or a life insurance policy to protect his widow if he died young. Although in London the first life insurance companies were being formed, to help professional men in Franklin’s position, nothing of the sort existed in the colonies.
He and Deborah needed somebody with the talent and drive to take on the family business when the moment came. If it could not be a son or another kinsman it would have to be a former hired hand. But although journeymen came and went on Market Street, they lacked the wide range of skills that Franklin had acquired, and which he would need from a partner. Only one man in Philadelphia might have fitted the bill: a clever Welsh immigrant, Lewis Evans. A former Quaker but now an Episcopalian, he became a Franklin family friend, with Deborah serving as godmother to his daughter when she was baptized at Christ Church. Evans made a living as a merchant, scrivener, and draftsman. He did jobs for Franklin; he shared Franklin’s fascination with iron; and from his home he sold the iron fireplaces. But for all his talents—he was, said a friend, an “ingenious engineer”—Evans had a difficult temperament. He was “a queer fellow,” said another. Besides, he was too old to be Franklin’s successor. Evans was already in his forties.4
So everything still depended on Franklin’s and Deborah’s hard work and their physical health. But this could never be taken for granted, in colonial towns so often swept by epidemics. Three of Franklin’s sisters had failed to see the age of forty-five. His brother James had died at thirty-eight. Nor could Franklin be certain of keeping his assembly clerkship, and the government printing contracts that went with it. By 1742 the glory days of the Triumvirate were a distant memory.