Benjamin Franklin and Eighteenth-Century English Medicine

a talk prepared for the Northwest Independent Scholars Association, February 7, 2006 

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            Contrary to popular belief, the so-called "germ theory of disease" --the idea that diseases were transmitted from one individual to another by microorganisms--was not invented by Pasteur.  Many British physicians and a small handful of others had thought for over a century: that many diseases, particularly those that were characterized by fevers or rashes, were contagious, and a few hypothesized that the pathogens were alive.

            Theories of contagion first developed following the terrible Renaissance epidemics of Black Death and were first applied only to a very small group of illnesses: especially plague, eye infections and syphilis.   The traditional view of disease, based primarily on the work of Galen, did not have any room for contagion.  It viewed disease as a "disorder" caused by an internal imbalance.  Illnesses arose from some excess or deficit in the fluids that circulated within the body.  These imbalances in turn could be caused by disorders in the natural world; particularly by attributes of the weather.  If it was too cold, too hot, too dry or too wet, then the body might reflect these disturbances in the atmosphere and susceptible individuals would fall ill.  Colds were caused by cold, wet weather and chilly night air.  Fevers were caused by an overheated atmosphere, hot rooms or bedclothes, or "heating" foods such as red meat and red wine.  This view was common until the late nineteenth century.

            When I started investigating 18c ideas about fevers, however, I found to my surprise that it was very common for late eighteenth-century British medical authors to assert that many fevers were contagious, and the environment played only a secondary role if it had any role at all.  One of the earliest works by members of this generation was the Account of the Sore Throat attended by Ulcers by Dr. John Fothergill, published in 1748.  Fothergill commented that this disease resulted from “.... a putrid virus, or miasma sui generis, introduced into the habit by contagion; principally by means of the breath of the person affected.  ... this ... contagious matter, produces effects more or less pernicious, according to the quantity and nature of the infection." 

            Fothergill was the leader of a very tight-knit group of medical and political reformers who included the notorious radical scientist, Joseph Priestley, and the future President of the Royal Society, Dr. John Pringle.  It was the membership of this group; men who did not hold English University M.D.s either because of nationality or religious views who were the primary supporters of contagionist disease theory.[1]  The members of this circle were strong supporters of the American cause and natural allies of Franklin’s and he was accepted among this reforming medical community on equal terms.  His letters are filled with comments on medical topics; he treated patients with electricity, and on one occasion his medical advice, countermanding that of a very distinguished physician, was credited with saving the life of a patient. 

            Among his other medical interests, Franklin was determined to disprove the old idea that cold weather could cause a cold.  He and Pringle together commissioned the fatal physiological experiments of Dr. William Stark, who made various changes in his diet to see what effects it would have (he died of scurvy).  Stark weighed and measured everything he ate or drank and also weighed himself by sitting on a large balance.  Franklin persuaded Dr. Stark to weigh himself for a period without his clothes, and then again for a period with his clothes.  They discovered that he lost more weight naked than clothed, thus undermining the entire basis for the idea that cold weather “stopped up” the pores of the body and the resulting blockages caused physical malfunctions.  Franklin thought instead that colds were caused by the “frouzy, corrupt air from animal substances, and the perspired matter from our bodies” which was forced into our bodies when conditions prevented evaporation.  In other words, he believed that colds were contagious.  At the time he was writing this was a very unusual opinion. 

            After I had been working on this circle for a few months, I learned that contagionist disease theory had been developed much earlier in the eighteenth century but it took me years to realize that there was also a connection with Franklin and that his theories of contagion and air circulation probably antedated his second visit to England in 1757. 

            A complete account of the "germ theory of disease" had been published by an obscure physician, Dr. Benjamin Marten, in 1720.  Marten's book, A New Theory of Consumptions stated quite firmly not only that phthisis (that is, consumption or tuberculosis) was contagious but that it and many other diseases were transmitted by "some certain species of Animalcula or wonderfully minute living Creatures."   Furthermore, Marten understood that this meant that every contagious disease could be identified with a specific causative organism: a cough could not become a consumption if the necessary organism was not present.  He wrote that these microscopic animalcula differed in their contagiousness, and that the ones that caused consumption were less contagious than others, requiring prolonged contact to spread.  Differing viability also explained some of the geographic and epidemiological patterns of particular diseases.  He also argued that the life cycle of particular animalcula could determine the specific sequence of symptoms manifested by certain diseases.

            Marten's book was popular enough to appear in a second edition in 1722.  Then, apparently, both Marten and his book disappeared completely.  His work was only rediscovered when a young doctor named Charles Singer was browsing the used book stalls at the turn of the twentieth century and picked it up.  This discovery changed his life, but no matter how hard he tried, he could never learn anything about its mysterious author beyond the fact that he signed the title page "Benjamin Marten M.D." and he dated its preface from his house near Red Lion Square, Holborn.  Since then, historians have sought for the tiniest scraps of information about this mysterious man and his astonishing book.

            In addition to Marten's work two other events of the early 1720's played an important role in ideas about disease. The first was an epidemic of Plague at Marseilles, which provoked many pamphlets and treatises, some of which argued that the Plague was contagious.  The most complete version of this was provided by a young botanist named Richard Bradley, author of what Singer has called “The best attempt to solve the problem of the nature of infection” of any author before Pasteur.   This epidemic also resulted in the publication of a classic work by Dr. Richard Mead that argued that the infection of the Plague consisted of particles carried through the air or transferred from person to person by carriers or objects.  It was on Mead’s recommendations that the British Government imposed a strict quarantine on foreign vessels. 

            The second event was a major epidemic of smallpox in 1721.  This epidemic led to the introduction of inoculation both in Massachusetts and in England.  The first details about the methods used in Turkey were provided by a letter by Emmanuele Timoni to a member of the Royal Society in 1713.  The first English inoculation took place in April of 1721 and was followed by an experiment on Newgate prisoners carried out by Dr. Hans Sloane, President of the Royal College of Physicians and Secretary, later President, of the Royal Society, in August, 1721.  Sloane also served as the patron and protector of the scapegrace Bradley (and he needed a lot of protecting).  

            During the same epidemic, inoculation was brought to Boston by a congregationalist minister, Cotton Mather.  Mather had read about Timoni’s letter in the Transactions of the Royal Society.  He had also heard about inoculation from a slave and resolved to try it the next time an epidemic hit Boston.  When smallpox appeared in 1721, he persuaded a local doctor, Zabdiel Boylston, to inoculate his own son and two slaves.   The two men aroused fierce opposition, and for a time inoculation was banned by the City.  The opposition was fanned by the anti-inoculation editorials published by James Franklin and was so bitter that Mather wrote it had made Boston "almost a Hell upon Earth”. At one point a bomb was thrown into his house.  Nevertheless, they persevered, inoculating 242 people with just 6 deaths. 

            Unlike Marten's book, inoculation permanently transformed Western ideas of disease.  The doctors were able to prove beyond question that a small amount of matter could be taken from one patient, put in a box, carried around, and transferred to a second patient.  When it entered the second patient's body, it produced a predictable sequence of symptoms that were virtually identical to those that had affected the first patient, unaffected by the climate, the weather, or the diet of the patients.  The Fellows of the Royal Society were sufficiently interested in the possibility that smallpox “matter” contained living organisms that they commissioned their Curator of Experiments, John Theophilus Desaguliers, to examine it under a microscope to see if it contained animalcula.  They also sent a request to Antoni van Leeuwenhoek at Delft, the best microscopist in the world, asking whether he could find anything.  Both Desaguliers and Leeuwenhoek reported that they could not find any animalcula, casting doubt on the theory of living contagion.

            So there was at least one group of contagionists and medical reformers during the 1720s, and another group of medical reformers that was increasingly contagionist after 1750.  What I could never find was any significant connection between them.  Fothergill, for example, quoted extensively from Spanish and other European doctors in his treatise on the sore throat, but did not refer to any indigenous sources.  Pringle quoted a Swedish work on contagion as if it were news.  The contagionists in the later eighteenth century were religious sectarians (often radicals) and social reformers.  But were there any links between their work and the obscure authors of the 1720s?         

            In a letter to Samuel Mather, Franklin recalled that in 1723, after he had already become a “thorough Deist,” he visited Boston, his home town, and was very surprised to be invited to visit Cotton Mather.  Mather, as we have seen, had been bitterly attacked by Franklin’s brother James, publisher of the New England Courant over his efforts to introduce inoculation.  Perhaps Mather had heard of the rift between the two brothers but Mather must have seen something very unusual in this young man to have sent for him despite the public enmity James Franklin had shown to Mather and his father.  All Franklin says about their meeting is a charming story about Mather shouting out suddenly “stoop, stoop” just before he hit his head on a low beam and then telling Franklin that if he remembered to stoop he would avoid many blows in life. 

            I imagine, however, that they discussed scientific and medical topics.  Franklin was still a very young man--about eighteen years old--but he was already a heretic and was unlikely to want to discuss religion with one of New England’s most notoriously pious ministers.  Mather had been named a Fellow of the Royal Society and sent the Society more than a hundred letters between 1712 and 1724.  He had published a treatise on measles in 1713.  By the date of Franklin’s visit, Mather had published leaflets on the inoculation in Boston and London that gathered statistics on its success.  At this time (between 1720 and 1724), Mather was collecting the notes for a book he was planning to publish on healing called The Angel of Bethesda and was probably boring everyone within earshot with his thoughts on the topic.  Surely a printer would not have been exempt.  As it happened, he never published the Angel.  But from that manuscript, we know that Mather read some of Richard Bradley’s works and also, with great excitement, Marten’s New Theory of Consumptions, because he depended on Marten’s work for the bulk of a chapter on animalcula as a cause of disease. It seems to have been one of the last things he read for The Angel, so it is probable that he was reading Marten’s work at about the time of Franklin’s visit.

            In The Angel, Mather wrote that microscopic animalcules often transmitted illness from one person to another.  Often, they would invade a body without causing a disease if bodily secretions and evacuations continued normally, but when the pores were stopped “thro’ cold or any other Cause” this prevented their being thrown off and many illnesses followed.  Franklin also believed that it was the accumulation of pathogenic particles when they could not evaporate that caused disease although Franklin did not describe the pathogenic particles as living organisms, and argued that it was not cold itself but other causes that led to their accumulation in the body.  Both, however, believed that these pathogenic materials passed from person to person. 

            Franklin had another opportunity to learn of Marten’s work when, on his first trip to England shortly after this meeting, he was misled about his financial support and was forced to support himself by working as a compositor in a printing shop.  One of his first assignments was to set a new edition of William Wollaston’s The Religion of Nature Delineated, a treatise that sought to derive the truth of Christianity from natural law. 

            Franklin, then aged nineteen, wrote and secretly printed one hundred copies of a refutation, arguing that God’s omnipotence had created a world where there was no pain without countervailing pleasure.  Pain was not evil; it was an inescapable source for all human activity.  He argued that everything was foreordained by a chain of cause and effect and there was no free will.  He also claimed that all pain and pleasure must be experienced in this life because the soul was mortal.

            Although Franklin later regretted publishing his views so freely, this treatise brought him to the notice of several men associated with the new science.  The first to seek him out was a Dr William Lyons.  In Franklin’s words, he “took great notice of me, called on me often to converse on those subjects, carried me to ... [an] alehouse and introduced me to Dr. Mandeville ... who had a club there, of which he was the soul, being a most facetious, entertaining companion.”  This throwaway comment by Franklin’s is the only known contemporary reference to a meeting with Mandeville or to his private activities.

            It is important to understand the extent to which these alehouse companions were flirting with imprisonment or ruin.  Denying the Christian trinity, atheism and blasphemy were crimes that were still punishable by death; the last execution had occurred in Edinburgh in 1697 when a young medical student, son of a local surgeon, was hanged for a few careless words to his friends that were overheard.  The execution took place despite his apology and recantation. Even though execution was unlikely by 1720, spells in prison were common for those who publicly supported anti-trinitarian or blasphemous views and imprisonment often led to death by fever.  Moreover, both the civil and the unofficial penalties for dissent remained severe.   Men like Isaac Newton took care to conceal their heterodox views to avoid professional ruin. 

            Franklin, however, was still a young journeyman with little to lose and much to learn by associating with these skeptics who sought him out.  It is just possible that among the convivial gathering at The Horns he actually met Benjamin Martin himself who had been trained by one of Mandeville’s oldest friends. 

            Mandeville had obtained his M.D. from Leyden.  In 1723, just before Franklin’s arrival in London, he had added his notorious Essay on Charity and Charity-Schools to his Fable of the Bees.  Although the first edition of this book (1714) had been ignored, the 1723 edition created a scandal and “became one of the most reviled targets of the public guardians of morality and religion; for some he appeared to be truly the Devil incarnate” for his attacks on piety, virtue and charity.

            Mandeville, a Dutchman, had developed a friendship with a much older compatriot, Johannes Groenevelt, who had settled in London in 1673. Mandeville’s first English publication was a poetic preface to a book of Groenevelt’s in which Mandeville heaped criticism on the Royal College of Physicians, which was prosecuting Groenevelt and his medical partners for entreprenurial practices at the Oracle clinic. For help, Groenevelt had turned to the powerful Hans Sloane, who apparently continued to assist him until his death in 1715/6.  There is also some evidence that Groenevelt shared Mandeville’s religious skepticism, for he was charged by his church with being a “socinian” like his medical partner, Christopher Crell.  (Socinians did not believe in the Trinity).

            In an attempt to salvage his medical reputation and advertise his services, Groenevelt had decided to publish an English edition of a Latin work he had written on the treatment of bladder stones.  This work appeared in 1706 and was translated by a London surgeon and venereologist named John Marten who specialized in venereal diseases and wrote “semi-pornographic” best-sellers about sex and syphilis.  (We have very recently found out that may have been the author of the anti-masturbation classic “Onania” which made him a very wealthy man.) 

            There is evidence that our author, Benjamin Marten M.D. was the younger brother of the controversial John Marten.  As we already know that John Marten and Johannes Groenevelt worked closely together, it is very likely that when Groenvelt mentioned his surgical student and leading assistant, “Mr.” Benjamin Marten, he was referring to the same man who later became “Dr.” Benjamin Marten.  Marten, Groenevelt’s right hand in his later years, and Mandeville, his friend and defender, must have known one another.

            Lyons also introduced Franklin to the Newtonian popularizer Dr. Henry Pemberton at Batson’s Coffee House in Cornhill.  Batson’s was a favorite gathering place for London physicians including the prominent Dr. Richard Mead.  It is not clear whether there was a regular gathering at this coffee house or whether this was just a private meeting.  Lyons, Mandeville and Pemberton were all doctors; and Mandeville engaged in joint consultations with Hans Sloane.   

            Perhaps Mandeville, a physician, member of the Dutch community in London and Grub Street regular, introduced Franklin to Benjamin Marten, or even to Richard Bradley, who had lived in Holland for four months while pretending to be a physician.  Bradley was perennially struggling to make a living through publication and must have spent much of his time with Grub Street booksellers.[2] 

            It seems very likely at least that the recent controversies about plague and smallpox would have been aired in these gatherings.  Batson’s coffeehouse was populated by physicians who had been immersed in the inoculation battle and Franklin had recently come from Boston, the center of the inoculation controversy in the colonies.   He doesn’t mention his own views during the contest in the 1721, but by 1736 he strongly supported the practice, and in 1759 he persuaded William Heberden Sr. to write a pamphlet encouraging Americans to inoculate their children.  This included a detailed introduction by Franklin himself. 

            Pemberton is generally described as a “surgeon” but in fact he was a physician, having obtained an M.D. from Leyden. He had studied medicine at St. Thomas’s Hospital. He became an F.R.S in 1720.  Although initially Newton was suspicious of him, Pemberton developed a very close friendship with Richard Mead, Newton’s physician, and assisted Mead with the eighth edition of his treatise on the Plague.  A work of Pemberton’s on kinetic energy finally broke the ice with Newton, and he asked Pemberton to assist him with the third edition of his Principia (1726).   Two years later, Pemberton became the Gresham professor of Physic.  He also edited the fifth edition of the London Pharmacopoeia for the Royal College of Physicians.  Despite this, Pemberton never became a Fellow or even a Licentiate of the Royal College of Physicians. 

            It has been conjectured that Newton was part of a covert anti-trinitarian network.  We know that he met with and quietly assisted Samuel Crell, the grandson of a very distinguished Polish Socinian and the brother of one of Groenevelt’s medical partners.  Mandeville was openly anti-clerical and hostile to traditional medical authority. We may assume that Lyons, and Pemberton, both medical men, were also interested in heterodox ideas and that is why they cultivated the young Franklin after he published his little tract.  Although he was the son of a famous dissenting minister, Richard Mead has also been described as a deist.  His son-in-law was a militant freethinker. 

            Pemberton was not able to introduce Franklin to the aged Newton, something that Franklin greatly regretted.  He was more fortunate in meeting Sloane.  He wrote a letter to Sloane introducing himself and asking if Sloane was interested in purchasing a purse of asbestos.  Sloane visited Franklin and invited him back to view his own collection.  He also purchased the purse.[3]  After returning to America, Franklin studied Pemberton’s View of Sir Isaac Newton’s Philosophy, Boerhaave’s New Method of Chemistry and works by Desaguliers and Stephen Hales--works which would equip him with a basic grasp of the tenets of the new natural philosophy.[4]  

            Because he was so young on his first visit to London and lived so long, Franklin is nearly unique in his participation in both the radical scientific circles of the early eighteenth century and those of the late eighteenth century.  Moreover, his religious and medical ideas remained relatively consistent from his earliest years until the end of his life.  It seems likely that he was developing those ideas at the time of his first visit to London and that if he did not acquire any of them from Mather he did learn  a great deal about contemporary medical work from listening to both the Sydenhamians and Newtonians who gathered around Mandeville.

            When I started working on this topic, I thought that it might be possible to show that Franklin was one of the pathways between the ideas of a living contagion that circulated in the 1720s and the contagionist theory of the later eighteenth century.  The more I have worked on this, however, the less certain I am that this was the case.  Franklin unquestionably believed that colds were contagious, at a time when virtually every other medical author blamed exposure to cold air.  He certainly had opportunities to discuss contagionism with early eighteenth century physicians and medical authors and he was intimately associated with the contagionists of the later period.

            However, although he discussed medical topics frequently with his medical friends such as Pringle and Fothergill, it seems that their views on contagionism evolved separately from Franklin’s, although along similar lines.  This is not surprising given that they all read the same works, particularly papers published by the Royal Society.  It is possible that Franklin’s belief that influenza might also be contagious spurred Pringle’s effort of 1758 to collect observations on influenza from his colleagues; the first of several major efforts in this area over the next half-century that produced some important work.  (In 1775, Fothergill embarked on a similar, but much larger effort). 

            Although we may speculate that Franklin was exposed to Marten’s idea of a contagium vivum in the 1720s, it seems unlikely that he ever found it plausible enough to be worth considering.  Of all eighteenth-century thinkers, he was the most resolutely mechanistic.  He wanted to explain every natural event by a process that he could observe and measure.  Vitalism had roots in a religious and philosophical approach to medicine that was completely alien to him (though not to Mather).  Pringle did become interested in the idea of a living contagion, but it came to him from Sweden, not from America.   If Franklin contributed anything to the evolution of British medical thought besides his observations on plumbism and his support for inoculation, it was probably his insistence that the logic linking the weather to diseases needed to be viewed with skepticism.  His project with Pringle to commission Stark’s physiological experiments might have borne more fruit had it not been for Stark’s death and the loss of his notes. 

            Franklin’s story is of greater interest for the light it sheds on an obscure group of medical men in London early in the century.  His comment about Mandeville is the only reference from a contemporary about the private life of that author.  Without that single sentence in Franklin’s autobiography, we would not have known of this “facetious” sociable group at The Horns nor that Pemberton and Lyons were part of this circle.  Unlike Newton, Sloane himself has left little evidence of his personal beliefs, but when we look at his friends and protégés we find that he consistently helped those on the radical end of the political and religious spectrum. Franklin’s story also suggests that the small number of known and suspected eighteenth century heretics were perhaps more evangelical than we had previously realized and that physicians and surgeons may have played an important role in propagating these dangerous views. Franklin entered their circle for a brief period in 1724-5 when he was an impressionable young man, and he was to play a major role in disseminating their skepticism, if not their contagionism, as a mature politician and writer.



[1]To become a Fellow of the Royal College of Physicians required an MD from Oxford or Cambridge.  Physicians qualified on the Continent could sometimes “incorporate” their degrees and become Fellows, but those holding Scottish degrees were ineligible.  Men ineligible for Fellowship could still obtain a licence to practice medicine in London if they passed an oral exam on Galen and Hippocrates held in Latin (later, in Greek).  Pringle was named a fellow “Speciali Gratia” (by special grace) after a complicated political contest. .

[2]Bradley was appointed the Cambridge Professor of Botany on Sloane’s recommendation in 1724, about the time of Franklin’s arrival, but it seems likely that he still spent time in London.

[3]Walter Isaacson, Benjamin Franklin (New York: 2003), 47 and see Franklin’s Autobiography, p.52.

[4]I. Bernard Cohen, Benjamin Franklin’s Science, p. 19.


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