Benjamin Franklin and the neurosciences

 

 

Stanley Finger

 

Lecture delivered by Ottorino Rossi Award 2006 winner, Prof. S. Finger, Department of Psychology and Program in Neural Sciences, University of Washington, USA

 

Reprint requests to: Prof. Stanley Finger

Department of Psychology

Campus Box 1125

Washington University

Saint Louis, MO 63130-4899, USA

E-mail: sfinger@wustl.edu

 

 

Summary

 

Benjamin Franklin (1706-1790), who is better known in other fields, especially colonial politics and international diplomacy, was an early, major contributor to the neurosciences from the New World. Among his accomplishments are: experiments on medical electricity as a possible cure for the palsies and hysteria; the first descriptions of how electricity affecting the brain can cause a specific type of amnesia; supporting the idea that cranial shocks might provide a cure for melancholia; showing that the cures performed by the Mesmerists to remove obstructions, including nerve blockages, rest on gullibility and suggestion, and recognizing the dangers, including those to the nerves, posed by exposure to lead. Franklin’s neuroscience was firmly based on experiments, careful observations, and hard data – and finding clinical relevance for new discoveries was always on his mind.

 

KEY WORDS: amnesia, Franklin, lead poisoning, medical electricity, Mesmerism, paralyses.

 

 

Introduction

 

Benjamin Franklin (1706-1790) was one of the greatest figures of the Enlightenment (1,2). Yet he was born into a working class family in Boston (then a colonial city with fewer than 8,000 inhabitants), was permitted just a few years of formal schooling, and was trained through the apprenticeship system not as a man of medicine or in the sciences, but as a printer.

Franklin would die at age 84 in his adopted city of Philadelphia, after having served Pennsylvania (and then multiple provinces) in England from 1757 to 1775, and his new country in France from 1776 to 1785. In the United States, as well as abroad, he was and still is best remembered for his civic and diplomatic exploits, and his Poor Richard’s Almanack, autobiography, and othe writings. He is further cited for his moral philosophy, economic theories, inventions (e.g., bifocals), and experiments on the nature of electricity.

A true polymath, Franklin also contributed to other fields in significant ways. One such area, often overlooked or glossed over by his many biographers, is the neurosciences – a twentieth-century term that encompasses both basic scientific studies of the nervous system and associated clinical disciplines (e.g., neurology, neurosurgery). That Franklin can be considered a neuroscientist derives from the subjects he investigated, his advocacy of the experimental method, his use of clinical trials to study ways of treating disorders of the nervous system, and his firm reliance on hard “scientific” data.

In this article, I shall summarize some of Franklin’s most significant contributions to the broadly-defined neurosciences (for more thorough treatments, see 3-6). These will include his experiments on medical electricity for disorders thought to involve the nerves; his descriptions of electric shock-induced amnesia; and what led him to embrace the idea that electricity applied directly to the head merited testing as a potential cure for melancholia. Comments will also be made about how Franklin headed the commission that discredited Mesmer’s theory of animal magnetism, while showing that suggestion can have a legitimate place in practical medicine. Additionally, it will be noted that Franklin conducted research and was an authority on the sources and perils of lead poisoning, and that he stimulated others to work on this problem, as well as on pertinent issues in the basic neurosciences, including whether electric fish really produce electricity – a finding with major implications for the neurophysiology of his day.

 

 

Franklin’s orientation

 

Throughout his life, Franklin was interested in new developments in natural philosophy and bedside medicine. In his highly successful Poor Richard’s Almanack and his civic-minded newspaper, the Pennsylvania Gazette, he included many pieces on preventing naturally occurring diseases, such as smallpox, and on new ways of treating the sick and injured (3, pp. 19-36).

Franklin’s orientation to the healing arts, as was true of most self-educated people, was not that of a theoretician. Influenced by Francis Bacon, Thomas Sydenham, and others who promoted a more empirical and pragmatic approach to bedside medicine, he favored data generated by experiments far more than theories, opinions, or casual observations. In fact, his writings related to the neurosciences are virtually devoid of theory, although some reflect a serious interest in physiology. Typically, they show a reliance on a step-by-step, trial-and-error approach and a desire to accumulate and assimilate raw data when addressing a serious medical need.

Franklin believed that he could better himself, best serve his community, and honor his God by finding new ways to help suffering humanity. He was also guided by a second belief – that even seemingly mundane discoveries could have unexpected consequences that might ultimately benefit humankind. Both his willingness to help others in need and his drive to find practical uses for new findings characterize his major forays into the neurosciences, all of which were also driven by his inherent inquisitiveness and love of discovery.

 

 

Medical electricity for the palsies

 

Doing things with electrical machines was in vogue in the middle of the eighteenth century, whether it was to learn more about the properties of electricity or just to amuse curious people (7-11). Franklin began his own forays into electricity in the 1740s, after personally witnessing an electrical demonstration by an itinerant electrician and then receiving a gift of some electrical equipment from Peter Collinson in England (12).

The majority of Franklin’s experiments dealt with the nature and properties of electricity. Among the issues that he and his “leather-apron” associates addressed in Philadelphia were whether there are two electric fluids or just one, how lightning could be captured, and whether lightning and electricity might be qualitatively similar. His initial findings and insights were sent as letters to prominent people, such as Collinson in London, and then packaged in his 1751 pamphlet, Experiments and Observations on Electricity, which would grow in size in future editions (12-14).

Franklin’s experiments and insights into electricity gave him international fame, and he was treated in many places as a celebrity for his many accomplishments. He also received numerous awards for his work in this field, including the Copley Medal and honorary masters degrees from both Harvard and Yale in 1753, and a doctorate from St Andrews in 1759.

It was while working on the properties of electricity that Franklin came across some papers from Europe suggesting that electric shocks from friction machines might have a use in the healing arts. Johann Krüger, a professor in Halle, Germany, first published this thought in 1744 and even predicted “The best effect would be found in paralyzed limbs” (15,16, p.5). His student, Christian Gottlieb Kratzenstein, successfully tested his professor’s hypothesis in 1745, although his patients seem to have had arthritic conditions, not strokes or other nervous system disorders (17,18). Still, the idea that applying mild shocks or perhaps drawing sparks from a charged body might be able to cure movement disorders was put into play. And when it did produce the desired effects, it created considerable excitement.

Nevertheless, the initial reports with stroke victims and people with head injuries, such as those relating to the trials conducted by the Abbé Nollet and Antoine Louis in Paris, and by Jean Jallabert in Geneva, were less than clear (19-24). Adhering to the motto of the Royal Society of London – Nullius in Verba (“On the words of no one”) – well before he was even elected a member, Franklin had a desire to see things for himself and to conduct clinical trials of his own. His patients included some of the most important people in the British North American colonies, as well as many others of lesser status whose names do not appear in his known writings (3, pp. 80-101, 4).

One of Franklin’s best-known patients was James Logan, a scholarly Quaker who had sailed to America as William Penn’s secretary. Logan enjoyed natural philosophy, had perhaps the best private library in the New World, and held many public offices, including acting Governor of Pennsylvania. He also had at least one stroke prior to 1750, the year in which he suffered another one that markedly affected his right side and impaired his speech. Prior to this event, Logan knew about Franklin’s electrical experiments and had heard about medical electricity. Thus, Franklin, whom he had long known personally, was called to administer shocks to his disordered side. To Franklin’s dismay, the electrical treatments failed to help and Logan died in 1751 at age 77.

Jonathon Belcher, a second prominent colonial, was also “stricken with the palsy” in 1750. Belcher’s attack took place during commencement for the College of New Jersey (later Princeton University), the school that he had helped to found. He was 68 at the time and, after discussing his condition with other physicians, also asked specifically for Franklin’s help. Political problems prevented Franklin from going to New Jersey to treat Belcher, but he sent equipment and instructions for its use. In 1752, Belcher informed Franklin: “I have ... been electrifyd several times but at present without any alteration in my Nervous disorder” (25, pp. 255,256). Belcher’s ability to move about continued to decline and he died five years later.

Franklin went to England and signed the register to become an official member of the Royal Society in 1757, the year Belcher passed away and one year after being notified of his election to the organization. With the efficacy of medical electricity being hotly debated, he was asked to present his own experiences with the palsies. Franklin dated his communication December 21, 1757, it was read on January 12, 1758, and it was published in the Philosophical Transactions later that year (26).

Franklin did not provide detailed clinical descriptions of his patients, nor did he reveal the number of patients treated. But he did mention in his 1757 communication how he drew sparks from the affected part and shocked palsied limbs with “two 6 Gallon Glass [Leyden] Jarrs ... repeating the Stroke commonly three Times each day” (26, p. 299). Further, when discussing outcomes, he stated unequivocally that the treatments he gave or directed had at best only short-term effects. In his words, “I never knew any Advantage from Electricity in Palsies that was permanent” (26, p. 299).

Franklin never altered his negative assessment of medical electricity as a cure for palsies of long duration, and specifically for the “common paralytick disorder”, an eighteenth-century term for stroke. In 1787, when Mather Byles penned a note to Franklin to ask whether he should try medical electricity for his condition, Franklin wrote back “I wish for your sake that Electricity had really prov’d what at first it was suppos’d to be, a Cure for the Palsy” (27, p. 656).

 

 

Success with hysteria

 

Hysteria (now conversion disorder) has a written history that dates back to antiquity (28-31). Among the ancient Greeks and Romans, it was thought to be a physical disorder of sexually unfulfilled women, with symptoms stemming from a dry uterus that wandered to affect other organs. During much of the eighteenth century, most people still looked upon hysteria as a physical disorder, and one most likely to affect women, because women were widely believed to have frail nerves and more impressionable minds. The guiding theory was that, much as a diseased body could disrupt the workings of the mind, a sick mind could affect the physical machinery of the body – including the nerves. Only later would the choking, paralyses, and losses of sensation signifying hysteria be viewed as purely mental problems, and not at least in part as physical problems of the seemingly afflicted body parts.

Franklin used medical electricity to treat a woman with hysteria in 1752. He joined Cadwallader (sometimes spelled Cadwalader) Evans on the case. Evans had trained as a medical apprentice and “C.B.” might have been his sister (32,33). A full report of the case appeared in Medical Observations and Inquiries in 1757 (34).

Evans wrote that C.B “was seiz’d with convulsion fits” in 1742, when she was 14. These convulsions “succeeded each other so fast, she had near 40 in 24 hours after the first attack. ... [Thereafter] her disorder continued in one shape or other, or, return’d after an intermission of a month or two, at farthest. Sometimes she was tortur’d almost to madness with a cramp in different parts of the body; then with more general convulsions of the extremities, and a choaking deliquium; and, at times with almost the whole train [of] hysteric symptoms ... (34, pp. 83,84).

An accompanying letter from C.B. provides additional information, revealing that she went to Franklin at the beginning of September 1752, hoping for some help. “I receiv’d four strokes morning and evening ... and indeed they were very severe. ... The symptoms gradually decreased, till at length they entirely left me. I staid in town but two weeks, and when I went home, B. Franklin was so good as to supply me with a globe and bottle, to electrify myself everyday for three months. ... I now enjoy such a state of health, as I wou’d have given all the world for ....(34, pp. 84-86).

The Evans article does not mention why he and Franklin decided to use electricity to treat C.B. In this context, three possibilities have to be considered. First, following then-popular medical theories and practices, the two men might have concluded, along with most everyone else, that hysteria could be treated with a stimulant. Electricity was the most powerful stimulant known, and people believed it capable of such things as tightening the nerves and increasing the flow of sluggish nerve juices.

Second, knowing how gullible people could be, Franklin might only have wanted C.B. to believe that this wondrous but really unproven new cure would work. As Franklin’s creation Poor Richard once stated, “As Charms are nonsense, Nonsense is a Charm” (35, p. 14). Thus, he might have been doing nothing more than using the power of suggestion to administer what was essentially a placebo to his patient. Given that C.B. had been told that the treatment was worthwhile, knowing that a highly respected scientist was her therapist, and then seeing his impressive glass instruments, could all have contributed to a desired “psychological” effect.

A third possibility is neither medical nor psychological. It is that Franklin might have tried electricity on C.B. strictly on a “let’s see” basis, knowing that it would not harm her if applied in moderation. Such a possibility would be consistent with his largely trial-and-error approach to practical medicine (3).

Of course, Franklin could well have had more than one reason for trying medical electricity. Moreover, whatever his underlying reason or reasons for turning to electricity, pretty much the same procedure would have been followed. The shocks would have been applied to or drawn from the seemingly affected parts over a number of sessions, and they would have been quite mild.

 

 

Shock-induced amnesia

 

Franklin experienced two fairly serious electrical accidents while conducting his experiments. His first response to what happened seemed to be genuine embarrassment, and he was not anxious to let others know how careless he had been. But through his accidents he also learned certain things that he felt should be made public. The most significant finding for him was that people could somehow endure strong shocks that affect the brain without severe, long-term consequences.

Franklin’s descriptions of his electrical accidents, which appeared in letters reprinted in later editions of his famous pamphlet on electricity, are especially notable for neuroscientists today because they provide what might be the first good descriptions of electric shock-induced amnesia (5). His initial communications mentioning this memory defect are dated 1750 and 1751, and one went to one of his brothers while the other was sent to Peter Collinson (25, pp. 82,83,112,113). Although the electricity entered his body through one of his arms, the jolt was so strong that he knew his brain had also been affected.

In the letter he sent to Collinson, he wrote that a jolt about equal to that of 40 common Leyden jars produced a “universal Blow from head to foot ... follow’d by a violent quick Trembling in the Trunk, which wore gradually off in a few seconds” (25, p.113). Yet he could not recollect what had actually happened, relying partly on witnesses to provide the details of the accident: “It was some Moments before I could collect my Thoughts so as to know what was the Matter; for I did not see the Flash tho’ my Eye was on the Spot of the Prime Conductor from whence it struck the Back of my Hand, nor did I hear the Crack tho’ the By-standers say it was a loud one; nor did I particularly feel the Stroke on my Hand ....” (25, p.113).

Franklin’s second accident occurred a few years later, and although the electricity directly entered his head this time, the personal incident was only briefly alluded to in one letter. That letter was sent to John Lining, a physician and talented experimental natural philosopher who lived in South Carolina, and it was dated 1755. In this letter, Franklin provided Lining with many more details about an experiment he had performed on six men, who also experienced the strange amnesia: “I laid one end of my discharging rod upon the head of the first; he laid his hand on the head of the second; the second his hand on the head of the third, and so to the last, who held, in his hand, the chain that was connected to the outside of the jarrs. When they were thus placed, I applied the other end of my rod to the prime-conductor, and they all dropt together. When they got up, they all declared they had not felt any stroke, and wondered how they came to fall; nor did any of them hear the crack, or see the light of it” (36, p.525).

Franklin informed Lining that he had no intention of placing these men in harm’s way. “You suppose it a dangerous experiment”, he wrote, “but I had once suffered the same myself, receiving by accident, an equal stroke through my head, that struck me down, without hurting me” (36, p.525). He then also briefly mentioned how a young woman had been accidentally shocked through her head. “She dropt, but instantly got up again, complaining of nothing” (36, p.525).

Many years later, in 1785, Franklin provided physician Jan Ingenhousz with the details of this, his second major accident: “I had a Paralytick Patient in my Chamber, whose Friends brought him to receive some Electric Shocks. ... I was oblig’d to quit my usual Standing, and plac’d myself inadvertently under an Iron Hook which hung from the Ceiling down to within two inches of my Head, and communicated by a Wire with the outside of the [Leyden] Jars. I attempted to discharge them, and in fact did so; but I did not perceive it, tho’ the charge went thro’ me, and not through the Persons I entended it for. I neither saw the Flash, heard the Report, nor felt the Stroke. When my senses returned, I found myself on the Floor. I got up, not knowing how that had happened. I then again attempted to discharge the Jars; but one of the Company told me they were already discharg’d, which I could not at first believe, but on Trial found it true” (27, pp. 308,309).

The shock-induced retrograde amnesia was not particularly exciting to Franklin, in part because it did not prevent men from immediately returning to work or women from still taking good care of their families. Moreover, people were not interested in classifying and studying the amnesias at this time. There would be much more interest in understanding and classifying the various types of amnesia in the next century (37-41).

Thus, this amnesia stands out as a notable instance in which Franklin made a basic contribution to the neurosciences without being able to find any immediate utility for it. Still, his discovery that people could experience even strong shocks to the head with little more than this minor consequence would be useful information to one of his best friends, Jan Ingenhousz, a prominent Dutch physician and experimental natural philosopher who served in the Austrian court.

 

 

Cranial electricity and madness

 

In 1783, Ingenhousz suffered an electrical accident that clearly affected his brain (42). The mishap involved a discharge from a large Leyden jar, and, based on what people in the room told him, he wrote that it “enter’d the corner of my hat ... Then, it entered my forehead”. The jolt created an amnesia for the event, much like that experienced by Franklin: “I neither saw, heared nor [sensed?] the explosion by which I was Struck down”. He also reported that, “I lost all my senses, memory, understanding and even sound judgment”. Ingenhousz remained unable to write that evening and was fearful that he would never recover his higher mental faculties.

To his amazement, however, he arose the next morning feeling strangely elated and even jubilant. Moreover, he believed that his quite exceptional mental faculties were now even better than they had been before the accident: “My mental faculties were at that time not only returned, but I [felt] the most lively joye in finding, as I thought at the time, my judgment infinitely more acute. It did seem to me I saw much clearer the difficulties of every thing, and what did formerly seem to me difficult to comprehend, was now become of an easy solution. I found moreover a liveliness in my whole frame, which I never had observed before” (42).

Ingenhousz felt so good, in fact, that he wrote to several “mad-Doctors” in London, hoping to convince them that applying electric shocks to the head might be “a remedie to restore the mental faculties when lost” (42). Prior to this time, there is little to indicate that severely mentally deranged patients were routinely treated with cranial shocks intended to affect the brain. Nevertheless, a few patients with headaches, “fits”, and hysteria appear to have been given light transcranial electrical stimulation (43).

Franklin replied to Ingenhousz just before he returned to America from his long but productive stay in France. In his letter of 1785, he gave Ingenhousz more information on his two electrical accidents, emphasizing that people could endure fairly strong shocks to the head without serious side effects (he knew, of course, that extremely strong shocks could kill a person, and he had even discussed the potential of electric executions with John Lining; see 36). He also informed Ingenhousz that he agreed it was now necessary to conduct some good experiments with “mad People”. In fact, he told his friend that he had already passed his suggestion on to a French medical “Operator”.

A number of publications describing how deeply melancholic patients were treated with cranial electricity came out after Ingenhousz presented this idea and Franklin embraced and promoted it (6). John Birch in England, T. Gale in the United States, and Giovanni Aldini in Italy were among the men of medicine who published these case reports (44-46). All described notable therapeutic successes with melancholics, including some who had been suicidal.

None of these “operators” mentioned the amnesia noted by Franklin in their reports. This omission is understandable, because they probably would not have viewed it as being of clinical significance. Also, the shocks they employed, although described as fairly strong in some cases, would not have been as massive as those that jolted Franklin and Ingenhousz in their accidents (i.e., there is no mention of people falling down).

Birch, Gale, and Aldini never mentioned Franklin or Ingenhousz in the context of what they now demonstrated therapeutically. Some possible reasons for this “omission” are that the Ingenhousz and Franklin communications were never published; that citing sources was not the same two hundred years ago as it is today; and that what Ingenhousz and Franklin had proposed could have spread from person to person just by word of mouth. Of course, the idea could also have stemmed from some other logic or experiments, and not from Ingenhousz’s reasoning or Franklin’s endorsement. Thus, gaps remain in the historical record, although there are reasons to think that Ingenhousz and then Franklin at the very least helped to put the idea of cranial shocks for severe melancholics and other “mad” patients into general circulation.

The idea of using cranial shocks for depressed and severely mentally disordered patients would reemerge in 1938, with Ugo Cerletti and Lucio Bini in Italy (47,48). These physicians differed from the eighteenth-century pioneers by deliberately using much stronger electroconvulsive shocks (ECT). Further, they and their followers based their treatments on two mistaken beliefs. One was that seizures somehow protect against schizophrenia, and the other was that disrupting memory is essential for the cure (49,52).

Cerletti and Bini showed no recognition in their written reports of what had occurred at the end of the eighteenth century. Unfortunately, it is still commonly believed that successful cranial shock treatments emerged with their work in the twentieth century. What took place late in the eighteenth century is, to say the least, clearly worthy of more attention.

 

 

Mesmerism

 

Franklin’s experiences with electricity and medicine, his legendary skepticism, his firm belief in the power of experiments, and his good name, literally brought him face to face with Mesmer. And along with medical electricity, Mesmerism was another great healing fad of the eighteenth century (3, pp. 219-250; 53-56).

Franz Anton Mesmer was a German-born physician who received his medical degree in Vienna in 1766. It was his belief that he could control an invisible force to heal sick bodies. He first called this force “animal gravity”, but after 1775 he referred to it as “animal magnetism”. Mesmer specifically claimed that he could manipulate it to remove or overcome the hidden obstructions that made people feel sick, including blockages of the nerves. Real magnets, which he had used therapeutically when he first started, were not even needed.

After being forced out of conservative Vienna, Mesmer settled in Paris in 1778. Maintaining that electricity and animal magnetism might be one and the same, perhaps subspecies, or at least close cousins, he wanted to meet Franklin, who then resided on an estate in Passy, a fashionable suburb of the city. Most of all, Mesmer wanted Franklin’s support for his theories and practices, an endorsement that would certainly raise his own stature. This was something he badly needed professionally, because many influential people were questioning his theories and practices, and even challenging him in public (56).

Franklin accepted an invitation to dine with Mesmer at the latter’s home in 1779. Although he did not question Mesmer’s ability to cure some people in his elaborate séances with his tubs (baquets) containing “magnetized” water and protruding iron rods, or with his metal wand, the American ambassador to France remained skeptical of Mesmer’s physical theory of animal magnetism. In a letter dated March 1784, Franklin wrote: “If these People [patients] can be persuaded to forbear their Drugs in Expectation of being cured by only the Physician’s finger or an Iron Rod pointing at them, they may possibly find good Effects tho’ they mistake the cause” (27, pp. 182,183).

Later that same month, and under enormous pressure from his ministers and trusted advisors, King Louis XVI of France agreed to assemble a royal commission to evaluate Mesmer’s various claims. Franklin was the only foreigner asked to be on this commission and he was elected its head, in part because he was so well respected as an experimental natural philosopher who had studied possibly closely related electricity, but also because he was independent (not paid by the French government), and interested in practical medicine. Since he was suffering from gout and a large bladder stone, both of which limited his mobility, some of the experiments that he and Lavoisier probably took the lead in designing took place under his watchful eyes at Passy.

The first thing that the commissioners did was to try to measure Mesmer’s envisioned magnetic force with instruments. This failed. They next witnessed some cures performed by Charles D’Eslon (Deslon), Mesmer’s estranged disciple who now had his own clinic and had agreed to work with the commissioners after Mesmer refused to do so. They observed that some people were affected by what took place in the elaborate séances, sometimes going into “convulsions” and even passing out. Nevertheless, when the invisible force was directed at the commissioners and their families and associates, nothing happened. As stated in the English translation of their report, “Not one of the commissioners felt any sensation, or at least none which ought to be ascribed to the action of the magnetism” (57, p. 95).

At this point, the commissioners conducted a series of exceedingly clever experiments to see if the effects witnessed among the susceptible patients might be due to suggestion and gullibility. Some of these tests involved telling D’Eslon’s patients that the healer they believed in was doing something to them when he was not even present or that nothing was transpiring when, in fact, he was secretly mesmerizing them from behind a screen. The results of these experiments showed that the remarkable cures claimed by the Mesmerists could be explained by suggestion and gullibility, without recourse to some hypothesized cosmic force, which was what Franklin had thought from the start. In the translated words of the commissioners, “They authorize us to conclude that the imagination is the true cause of the effects attributed to the magnetism” (57, p. 114).

The official report was sent to the king later in 1784, and it bore Franklin’s name above those of the other commissioners (58). Within a year, the “Franklin Commission Report” was translated into English (57). The publication was devastating to Mesmer and his followers, whose influence and power now declined precipitously in France and in other countries. More positively, it illustrated the need to base physiological and medical theories on a firm foundation of good experiments. Additionally, it showed how suggestion could be incorporated into the practice of medicine to manipulate minds for beneficial effects.

 

 

Lead poisoning

 

All of Franklin’s aforementioned contributions to the neurosciences can be traced directly or indirectly to his interest in, and knowledge of, electricity. But not all of Franklin’s neuroscience had electricity as its basis. Importantly, he tried to understand and prevent lead poisoning, which was a problem of enormous proportions in the eighteenth century (3, pp. 181-196).

Lead began to be mined approximately 8,000 years ago in the Mediterranean region. It was used for art, cosmetics, pipes, pots, utensils, currencies, paints, poisons, contraceptives, and even medicines in ancient Greece and Rome, where it was associated with Cronus (Saturn to the Romans), the father and the gloomiest of the pagan deities. It has even been argued and supported by analyses on bone samples, that lead poisoning contributed to the decline of the Roman Empire, because it caused mental instability among the leadership and led to few healthy offspring (59,60).

Among the many problems that can be associated with lead poisoning, above and beyond mental instability and infertility, are a painful colic, a graying of the complexion, and a myriad of signs and symptoms indicative of nervous system involvement. The latter can include insomnia, fatigue, sensory and motor symptoms, and a blunting of the intellect. In advanced cases, hallucinations, delusions, and even convulsions may even be witnessed.

Franklin learned early on that lead could affect the use of the limbs. He and his contemporaries called this “the dangles” or “the drop,” sometimes adding the adjective “wrist”, “hand”, “ankle”, or “foot” before the noun. This knowledge was acquired in 1724, when Franklin was stranded in London as an aspiring 18-year-old without the promised funds he needed to buy printing equipment to open his own shop in Philadelphia, or the money to sail back to America. Hence, he took a job in a London printing house, about which he would write: “I there found a Practice, I had never seen before, of drying a Case of Types (which are wet in Distribution) by placing it sloping before the Fire. I found this had the additional Advantage, when the Types were not only dry’d but heated, of being comfortable to the Hands working over them in cold weather. I therefore sometimes heated my Case when the Types did not want drying. But an old Workman, observing it, advis’d me not to do so, telling me I might lose the Use of my Hands by it, as two of our Companions had nearly done. ... This, with a kind of obscure Pain, that I had sometimes felt, as it were in the Bones of my Hand when working over the Types made very hot, induced me to omit the Practice” (27, p. 531).

As a printer, Franklin would remain especially interested in occupational lead poisoning. In 1767, when he and physician John Pringle visited Paris, Pringle went to the hospital La Charité to obtain a list of the hospitalized patients who seemed to have signs and symptoms of lead poisoning. Franklin then went through the list, noting the occupations of the sick men. He discovered that they were employed in trades that exposed them to high levels of lead, including working as painters, metal workers, and printers. Further, when Jan Ingenhousz visited Normandy, he reported back to Franklin that the lead-poisoned patients in a hospital in Rouen were also mainly potters, painters, and other workers of lead.

Franklin shared this and other pertinent information about lead poisoning with George Baker, a member of the Royal Society and Royal Society Club, who was then investigating the “Devonshire colic” – a disorder he would link to the use of lead in the production of apple cider in this agricultural region of England (61,62). Franklin’s information helped Baker understand and then confirm the source and scope of the problem with careful observations and experiments.

Baker, in turn, repeatedly thanked Franklin in his treatises for the information he provided about occupational and other forms of lead poisoning. For example, in addition to citing the American for his information about occupational lead poisoning, Baker credited Franklin for helping him to realize that the Devonshire colic and a number of differently named epidemics in other parts of the world shared a common, metallic cause. To quote: “It seems not improbable that, if we had an opportunity of making an accurate inquiry, we might see reason to conclude, that the disease, called popularly the dry-belly-ache, which is common as well in the northern colonies of America, as in the islands of the West-Indies, ought to be referred wholly to lead, as its cause. My suspicions, concerning this subject, have been greatly confirmed by the authority of Dr. Franklyn of Philadelphia. ... Dr. Franklyn likewise informed me, that the colic of Poitou [a synonym for lead poisoning named after a region of France that had many epidemics] is not so frequent a disease in any of the colonies, as it was formerly; and that the reason, commonly assigned, is that the people now drink their punch very weak in comparison with that what they were formerly accustomed to, which used to be rum [which often contained lead from its production] and water in equal quantities” (62, pp. 161,162,168,169).

Baker’s landmark papers led to a better appreciation of the dimension of the lead problem, the often-overlooked sources of lead poisoning, and how the latter could be prevented and treated. But more than providing valuable information about lead poisoning to just one person, Franklin also spread the word in letters to other people, whom he fully expected would spread the pertinent information to still others.

One such person was Benjamin Vaughan in London, who held law and medical degrees. In 1786, Franklin sent him, at his request, a detailed letter on what he knew about lead poisoning (27, pp. 530-533). He began by presenting the story of how North Carolina had filed a complaint against New England rum, which resulted in legislation to outlaw leaded “worms” in its production. He then presented what he saw among workers who handed hot lead type, including his own experiences while employed as a teenager at Palmer’s London printing house. This was followed by some comments about the smelting operations he saw in Derbyshire, and what this might be doing to cattle that fed on the contaminated vegetation in the region.

Franklin even included a section on how drinking water can become dangerously leaded, writing: “In America I have often observ’d, that on the Roofs of our shingled Houses, where Moss is apt to grow in northern Exposures, if there be any thing on the Roof painted with white Lead, such as Balusters, or Frames of dormant Windows, & c., there is constantly a Streak on the Shingles from such Paint down to the Eaves, on which no Moss will grow, but the wood remains constantly clean and free from it. … I have been told of a Case in Europe, I forgot the Place [actually Amsterdam], where a whole Family was afflicted with what we call the Dry Bellyach, or Colica Pictonum, by drinking Rain-Water. It was at a Country-Seat, which, being situated too high to have the Advantage of a Well, was supply’d with Water from a Tank, which received the Water from the leaded Roofs. This had been drunk several Years without Mischief; but some young Trees planted near the House growing up above the Roof, and shedding their Leaves upon it, it was suppos’d that an Acid in those Leaves had corroded the Lead they cover’d, and furnish’d the Water of that Year with its baneful Particles and Qualities” (27, p. 532).

Near the end of his letter to Vaughan, Franklin discussed the occupations of the patients confined to La Charité with lead poisoning. In this section, he admitted that two well-represented hospitalized groups had initially puzzled him: specifically stonecutters and soldiers. “These I could not reconcile to my Notion, that Lead was the cause of that Disorder. But on my mentioning this Difficulty to a Physician of that Hospital, he inform’d me that the Stonecutters are continually using melted Lead to fix the Ends of Iron Balustrades in Stone; and that the Soldiers have been employ’d by Painters, as Labourers, in Grinding of Colours” (27, p. 533).

Franklin concluded his letter to his English friend with words that are still applicable today: “You will observe with Concern how long a useful Truth may be known and exist, before it is generally receiv’d and practis’d on” (27, p. 533).

 

 

Concluding remarks

 

It can be dangerous to contend without qualification that someone was the first person to have a particular idea or was the first individual to do something. Part of the problem stems from the fact that ideas are often in the air, and that they rarely emerge in a socially or intellectually sterile environment. Other factors have to do with lost records, how information might have been conveyed in the past, and changing definitions of going public with an idea or a finding. Yet even with these caveats, Benjamin Franklin would seem to be the first neuroscientist of distinction to hail from the New World – a contention that rests on his use of scientific methods, the subjects he chose to study, and just how much he did that altered the scientific and medical landscape.

Methodologically, Franklin was not one for philosophizing about medical problems. Instead, he turned to the methods of science with the best instruments he could build or buy to treat disorders then linked to the nervous system and, in some cases, to understand the tricks that could be played by the human mind, which he viewed as highly vulnerable. This meant collecting careful observations and relying on hard data and not hearsay “evidence” to justify his conclusions. Not tied to grandiose medical theories nor biased by larger-than-life figures of the past or present, his goals were to see things for himself, to discover new useful truths, and to present findings in easily understood language that would withstand the test of time.

With regard to the scope of his neuroscience, Franklin was more of an applied neuroscientist than a basic or laboratory scientist, although he made contributions to both fields. As noted, many of his findings stemmed from his interest, understanding, and acumen with electricity, which was very much in the public eye at the time. In this context, he asked whether electricity might help to cure disorders of the nervous system, only to conclude that it was not a lasting cure for strokes, as he and others had hoped. Notably, he also failed to find electricity helpful for deafness caused by smallpox (63, pp. 27-29), or for contractures and seizures caused by what was probably an abscess, a tumor, or some other brain disease (64, pp. 95-97).

Yet Franklin did observe that medical electricity applied to the affected body part could be useful for hysteria, although neither he nor Evans ever revealed why it was tried, nor speculated on why it might have worked. Further, he was enthusiastic about calling for clinical trials with cranial electricity for severely melancholic and other mad patients. Jan Ingenhousz had provided him with this idea, but it was based in part on what Franklin had previously written about enduring fairly severe electric shocks to the brain without suffering serious, lasting effects.

Also in the clinical sphere, Franklin played a leading role in evaluating the theories and practices of Franz Anton Mesmer. His conclusion, based on a series of clever experiments, was that Mesmerism did not involve channeling an invisible force called animal magnetism into the patient’s body to remove blockages, including obstructions of the nerves. Rather, whether the Mesmerists knew it or not, they were skillfully playing on gullible minds and their cures were more in accord with faith healing. Importantly, Franklin felt that manipulating the imagination could be useful with the right patients, and he believed that suggestion and even instilling a positive attitude merited consideration in bedside medicine.

Yet another of Franklin’s clinical neuroscience contributions had to do with understanding lead poisoning and warning people of the dangers of working with or using lead, which could affect the nerves and the brain. Here he worked more behind the scene, but he was again remarkably perceptive, especially about occupational lead poisoning and how tainted beverages (especially rum made in the mainland colonies or the West Indies) could cause problems. Not mentioned above, but certainly worthy of mention now, is that he even did some tests on lead, exposing birds to it or other metal fumes. He presented some of his findings when promoting his Pennsylvania Fireplaces (“Franklin stoves”), which were constructed of iron, a metal he found to be safe (65, p. 419).

Franklin was most interested in helping people, but he also valued basic scientific findings, even if they did not seem have any clear applications to the human condition. His discovery of shock-induced amnesia represents one of his previously overlooked contributions to the basic neurosciences, and it came about entirely by accident. To his credit, he still wrote about the amnesia and then published some of his letters from the 1750s in his famous pamphlet on electricity, in order to make this finding more public.

With his inquisitiveness and close association with the Royal Society while in London, Franklin also played a role in basic neuroscience experiments carried out by others. Some of his help and endorsements, although not mentioned in the body of this article, reveal that he maintained a serious interest in how the nerves might work and that he was most drawn to ideas backed by good experiments. In this context, he gave advice and encouragement to John Walsh, a Fellow of the Royal Society who set forth in the 1770s to determine if electric fish do, in fact, generate and release electricity (66,67).

Walsh performed many experiments on the electric ray (torpedo) and subsequently on an electric eel from South America, and he communicated the results of his initial experiments to Franklin. Not to be overlooked, Walsh wrote his notable 1773 Philosophical Transactions paper on the ray in the form of a letter to Franklin (68). Jan Ingenhousz, who was close to Franklin and well aware of Walsh’s experiments, also conducted investigations on the ray and then on the electric eel Walsh had in captivity in London (69,70).

The sparks obtained with specialized fish suggested something important about the nervous system – something that was much more speculative prior to the 1770s. The findings of these experiments indicated that the nerves of at least some specialized creatures might carry electricity. This possibility would stimulate new laboratory experiments on “animal electricity” in amphibians and mammals. In the minds of Galvani and Aldini, among others who would go on to change the physiological landscape as the eighteenth century drew to a close, these findings were first steps toward understanding the physiology of the human nervous system and how to treat some dreaded disorders more effectively.

Benjamin Franklin was a talented and enlightened man, and an individual wonderfully suited to the sciences and medicine because he was so interested in the world around him, experimenting to learn more, and in sharing information that might inspire or help others. This year marks the 300th anniversary of Franklin’s birth, and neuroscientists, both basic and applied, should feel especially honored to know that he was more than just a politician, a philosopher, and a writer. A giant in so many different ways in his day, he was also one of us.

 

 

Acknowledgments

 

The author would like to thank Chris Smith, Marco Piccolino, François Boller, and Paolo Mazzarello for their perceptive comments on an earlier draft of this paper.

 

 

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