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The Classic: The History of Instrumental Precision in Medicine

Mitchell, S., Weir

Clinical Orthopaedics and Related Research: August 2003 - Volume 413 - Issue - p 11-18
doi: 10.1097/01.blo.0000079770.06654.5a
SECTION I SYMPOSIUM: Issues in the Design, Analysis, and Critical Appraisal of Orthopaedic Clinical Research:
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(Reprinted from Mitchell SW: History of instrumental precision in medicine. Univ Med Magazine. October 1841.)

    Silas Weir Mitchell (Fig 1) was a privileged citizen of Philadelphia, the son of a prominent physician and husband of the daughter of a merchant prince. At the age of 15 years, he enrolled in the University of Pennsylvania, but his progress was delayed by an episode of active pulmonary tuberculosis from which he recovered and never had a recurrence.

    Fig 1.

    Fig 1.

    Mitchell’s medical education consisted of the 2-year course offered by the Jefferson Medical College from which he received his medical degree in 1850. After this, he went to Paris for additional education and was influenced by the lectures of Claude Bernard. On returning to Philadelphia, he joined his father in practice.

    In addition to his medical practice, Mitchell did an extensive series of experiments leading to the publication of a monograph on rattlesnake venom. With the outbreak of the Civil War, Mitchell became a contract doctor for the Union Army. From his experience in the army, Mitchell produced his important study of what we now call posttraumatic sympathetic dystrophy. After the war, Mitchell renewed his experimental work, and maintained a large medical practice. In 1870, Mitchell joined the staff of the Orthopaedic Hospital and developed a clinic for children with neuromuscular diseases. As a result of his interest in neurologic problems, his practice became almost entirely devoted to neurologic diseases.

    Amidst all of his medical activities, Mitchell developed a wide reputation as a writer, particularly of historic fiction. He also wrote poetry.

    The following classic article is one of his papers relating to the history of medicine.

    Leonard F. Peltier, MD, PhD

    I shall confine myself almost entirely to the story of the earlier efforts to attain accuracy by instruments in the study of the pulse, respiration and temperature. It is not in the books of medical history. In but one of them is there anything interesting. It is here and there in memoirs, journals, lay biographies, rare old folios and forgotten essays.

    The latter part of the sixteenth and the first half of the seventeenth centuries was a germinal period in medicine. It saw advances in anatomy and physiology which led up to Harvey’s splendid discovery. It saw, too, the failure of his thesis to influence medical practice immediately or largely. The same period in Italy beheld the first attempts at precision as regards temperature and the study of the pulse. This was the birth era of instrumental accuracy in medicine; but many a day went by before the infant attained to useful manhood. Most strange it is that the seeds of scientific thought as to the first heat records and the pendulum were cultivated in the garden of medicine. Between 1593 and 1597 Galileo, some time a student of medicine, invented the crude open thermometer or thermoscope.

    The thermometer of Galileo was, as I have drawn it, a tube of glass, open below and ending above in a bulb. This bulb having been warmed, the open end of the tube was set in water, so that as the bulb cooled the water rose in the tube. Then any heat applied to the bulb caused the water to descend, the reverse of that which occurs in the more modern instrument. This coarse thermoscope was obviously a barometer as well as a rude measurer of the change of temperature. A slight gain in the weight of the atmosphere might easily neutralize an increase of heat. It was not an accurate instrument, nor does Galileo seem to have rated it highly since he nowhere mentions it in his works. Others thought more of it. The approximate date of this invention is set for us by one Padre Benedetto Castelli, in a letter about the treatment of a wounded man, written to one Cesarini, in 1638. He calls to mind the fact that Galileo had thirty-five years before shown him the air thermometer. A Venetian noble, Giovanni Francesco Sagredo, writes to Galileo in 1613 that “the instrument you invented I have bettered.” Sagredo divided the scale into 100 divisions, and two years later seems to have hermetically sealed the tube, and thus given us the modern instrument. Nevertheless, says Viviani, it was little employed in its improved form; and for years afterward physicians, as we shall see, made more or less use of Galileo’s rude thermometer, of the errors of which Viviani, Galileo’s pupil, was well aware. But concerning this invention, so carelessly made, raged a battle of words scarcely yet at an end. Renou, in a very full book on thermometers, does not so much as name Galileo. Bacon, Cornelius Drebbel, and, as we shall see, Sanctorius have all described the crude open thermometer. Fludd, in a curious, rare book (Philosophia Moysaica, Gouda, 1638), speaks of it, as was then common, as the Speculum Calendarium (Mirror of the Seasons), and says he got the figure and description from a manuscript more than fifty years old; in another of his works, however, he speaks of the manuscript as being at least seventy years old; clearly no accurate deduction as to priority of discovery can be drawn from such conflicting statements. And finally, Paolo Sarpi was claimed by his biographers to have invented the thermometer. No date was set; but Foscarini, in his work on Venetian Literature, observes that Fra Paolo in his notes speaks of the thermometer, and, according to his recollection, puts the year of invention at 1617.

    Much of the early interest as to the thermometer was as to its medical value. I relegate to my notes, or appendix, the bulk of evidence as to prior discovery, which may not be without interest, because it is just where Wunderlich begins fully to tell the story of the modern medical use of thermometers that I shall leave off.

    That so eccentric a man as Fludd should have been seriously accepted as evidence is odd enough. He had, as others had, a chance to know what went on in Padua. From the days of Elizabeth every man of fashion, and especially the English, traveled in Italy. Here, too, wandered all who studied, or were fond of science, and it was to Padua—which Sanctorius called the Garden of Science—that Bacon came, and Drebbel, and this same Fludd, and the greater Harvey. The towns of Italy were the exchanges of Europe both for commerce and for science. From them men took home what they saw or heard, describing them unquestioned (as did Bacon the air thermometer), thus leaving the future critic to settle the question of originality. The temper of the time was not that of our day. Men worked along patiently. There were no journals; the letter or the lecture were the only means of early publication. The genius who to-day invents a new forceps or a new pessary yearns for instant type, and defends his offspring with virulence. Harvey knew of his great discovery in 1616, and it got into print in 1628. His lecture notes show that long before this date he was certain of the matter and clearly knew what he had done. Whence this seeming indifference? If, after his first lectures, some obscure Italian, hearing it, had gone home and stated in a book the facts of the circulation, we should have had a controversy more absurd than those which must have made the ghost of Harvey smile, if in that other world men smile at all.

    I have stepped aside to point out how it was that as to the minor, and even greater, discoveries of those days so much trouble arose, or has arisen, as to priority of claim. But it is now with the thermometer in medicine that we are concerned. Galileo, an astronomer, half a doctor of physic, made it; and a prince, a very great person in his day, Duke Ferdinand II of Tuscany, still further improved it, and constructed divers forms for use in medicine. But this was as late as 1646. In 1876, some of the Duke’s pulse thermometers were shown at the South Kensington Exhibition of Instruments of Precision.

    In the meanwhile a new and interesting personage appears on the stage, and with him and the later grand ducal inventions and their applications ends for many a day the practical use of the thermometer in medicine. Santorio Santorini, born in Capo d’Istria, April, 1561, was educated at Venice, and at the age of twenty-one took his degree of Doctor of Medicine at Padua. In his commentary on Galen, I find a description of the air thermometer.

    “We have here,” he says, “an instrument with which we may closely measure the degrees of the recession of the heat of the external parts, and with which we may learn accurately daily how much we vary from the normal; also the degree of heat of your patients.” He does not claim the invention, but says no word of Galileo.

    “The patient,” he adds, “grasps the bulb or breathes upon it into a hood, or takes the bulb into his mouth, so that we can thus tell,” he says, “if the patient be better or worse, so as not to be led astray in cognitione praedictione et curatione.” He gives no table of temperatures, no records. No real good comes of it. The enthusiasm of the inventor keeps it for a while before the public, as we have seen happen in our own day.

    The thermometer lacked precision, and even when it had grown into this, want of knowledge of the cause of fevers, of their risks and how to lessen them, caused the mass of physicians to neglect an instrument which, as yet, had for them little practical value. Here and there, as time goes on, in the physiologies, and soon in the books of practice, we find rare statements as to the heat of man.

    And now, again, we have to thank an astronomer when, in 1701, Newton marks the blood temperature at 12° of his scale and uses linseed oil as the fluid. A little later Daniel Fahrenheit altered the scale over and over, and at last set 96° as the blood heat, and here we first come upon the use of armpit temperatures. Boerhaave is said to have suggested to Fahrenheit the use of mercury in his thermometer, as to which there is some doubt; at all events, the records of the famous Paduan Academy show that long before this date the Italians made use of mercury in their thermometers.

    Almost a century of silence falls upon medical thermometry. It is broken by a few allusive aphorisms of Boerhaave, and by doubting sentences of his famous pupil, Van Swieten, in 1745.

    De Haen, who saw Avenbrugger working beside him clinically for years and learned of this genius no lesson as to percussion, more clearly apprehended the value of thermal records. We have re-discovered much that is his; but his methods and instrument were clumsy, and his example proved valueless.

    And now, I turn to a not less amazing story of the application of instrumental accuracy to the pulse. I can imagine the discomfort with which you look forward to an essay on the pulse. I can promise that it shall not be dull, and can assure you that nowhere else is it told in full.

    An astronomer gave us the first rude thermometer, and it seems to have been another, Hermann Kepler, who first, and certainly before 1600, counted the human pulse, or at least left a record of having done this memorable thing. The publications in which he mentions the pulse date from 1604 to 1618. Does it not seem incredible that of the numberless physicians who sat by bedsides, thoughtful, with fingers laid upon that bounding artery, none should have had the idea of counting it? I quote in English what he (Kepler) says. This great but fanciful man seems to have believed the pulse to have some relation to the heavenly motions, and used the time of the pulse in connection with his arguments in favor of the Copernican system of astronomy. He says: “In a healthy man, robust and of full age, in one of melancholic complexion, or in a feeble man, generally for each second there is a pulsation of the artery, with no discrimination between systole and diastole; thus there should be in one minute sixty pulsations, but this slowness is rare, commonly seventy may be counted, and in the full-blooded and in women eighty, four to each three seconds. Briefly, in one hour 4,000, more or less.” The clock with which Kepler counted the pulse must have been such a “balance” clock as his master Tycho Brahe used.

    The next epoch marks a pregnant hour in the history of science.

    When Galileo, but eighteen years of age, a student of medicine, counted the vibrations of a lamp swinging in the gloom of the Duomo of Pisa, he conceived them to be in equal time. Desiring to test the truth of his conclusion, he is said to have used his own pulse as a measure of the correctness of the pendulum. Forty years later, in describing the accuracy of his first clockwork, he says with enthusiasm, “My clock will not vary so much as the beat of a pulse.” Says Viviani, his biographer, “The unerring regularity of the swing of a suspended lamp suggested to the young medical student the reversed idea of marking with his pendulum the rate and variation of the pulse. Such an instrument he constructed after a long series of experiments. Though imperfect, it was hailed with wonder and delight by the physicians of the day, and was soon taken into general use.” Unclaimed by Galileo, it was attributed to Paolo Sarpi, and clearly enough was appropriated at a later date by that notable genius, Sanctorius, who also, like Galileo, called it the pulsilogon. We have no drawing of Galileo’s pulsilogon, but it must have been identical with the simpler form as shown in Sanctorius. It is interesting to observe the tendency toward securing accuracy in medicine thus shown by Galileo at the outset of his medical career; Kepler’s works were not published until later, and could not have been fully known to him. With his thermometer and the pulsilogon, and with this picture of his testing the accuracy of the swing of the lamp by his own pulse, this marvelous mind passes out of medical history. Where he would have left it had he remained with us, who indeed can say? Of his loss to us a poet has spoken:

    Ah! when in Pisa’s dome

    He watched the lamp swing constant in its arc,

    He gave to man another punctual slave,

    And bade it time for us the throbbing pulse;

    Not that grave Harvey whom Fabricius taught,

    Not sad Servetus, nor that daring soul,

    Our brave Vesalius, e’er had matched his power

    To read the riddles of this mortal frame.

    And then he left us. Would our strange machine

    Had kept his toil, and cheated heaven’s fair stars!

    With the fame of Sanctorius as the discoverer of insensible perspiration, and with the inconceivable success of his aphorisms, we have nothing to do, nor yet with his theories or his morals, which seem not to have interfered with his appropriation of another man’s inventions.

    In his Commentary on Avicenna, he quotes Galen as to “the need to know the amount of departure from the natural state, which is only to be reached by conjecture.” But he, Sanctorius, has long been deliberating in what manner the amount of disease could be determined, and has invented four instruments. In his Methodus Vitandum errorum omnium qui in arte Medica contingent, he has also mentioned these. Then he describes what must have been the form of Galileo’s pulsilogon.

    Here are a scale and a bullet marked with a central white line. We swing the pendulum and note the pulse with the fingers. If the pendulum be faster than the pulse, we lengthen the line; if slower, we shorten it until they coincide. “Then,” he says, “we keep this degree in mind until the next day and compare it with a new record. And so we can study the pulse of health and disease.” Also he defines the values and defends the accuracy of the pendulum; but of Galileo not a word. He used the beats of his pulsilogon as a measure of the time one must breathe upon his air thermometer. Other forms are also given for our study. Thus we have to-day a pulse of so many inches (or degrees, if you please), and to-morrow it is longer or shorter, and the fever pulse is short, of course, but of results from all this we hear nothing in these huge tomes. The rest of this story is exasperating on account of its omissions. “These other instruments,” he says, “record the frequency and slowness of the pulse, and also of the time.” “In this,” he says, “are seven degrees of the difference of frequency and slowness observed by the index. Then each degree is divided into seven minutes (minuta), which are distinguished by the small index.” “The construction of the instrument we have described,” he adds, “in the book on New Instruments for Physicians.”

    This book he refers to more than once, and in his Inaugural Lecture (a rare pamphlet) promises it shortly to his students, and with it also that other, De Jucundissimis Medicinis. As to both one is curious, and especially as to this volume upon the most pleasant remedies. Perhaps these manuscripts are yet to be found among the treasures of some old Italian library. And if so, then only shall we know whether these Cotylae were rude watches, as seems likely. He proposes with them to measure the systole and diastole of the heart. To do this, he says, “We must measure expiration, for this we know corresponds to the systole, as does inspiration to diastole.”

    The explanation of the Cotyla is brief, and now incomprehensible, but we learn that between expiration and inspiration “the artery pulsates twice or in many three times.” Finally we are assured that what other physicians acquire by conjecture concerning the pulse, we are able to attain unerringly by the infallible skill of the pulsilogon. What a comfort he must have found it!

    And here the great Paduan professor, with his thermometer and pulse pendulum, disappears from history, dying in Venice in 1636, of a dysucturia (whatever that may be), in the parish of St. Fortunatus, a good saint as a stand-by for life or for death. He lies at rest in the cloisters of Santa Beata Servorum, in a mausoleum which he had made against the time of need. A strange proof of vanity is this care as to how the perishable part of man shall be housed in death. And certainly this man thought well of himself, but was also intensely loyal to our “Mistress Art,” which, he says, in a grandiose way, “is glorious, and a helper of men both in peace and amid the din of arms. An art above all others. Folly is it to despise science in general, but to scoff at medicine is not only folly, but wickedness—almost the sacrilege of bad hearts.” And now instrumental study of the pulse fails us for many a day. When Sanctorius died, Sydenham was a boy of nine. There is not a pulse count among all those vigorous sketches which this great Englishman drew with a master’s hand, and only once does Harvey speak of their number, which, he says, is from 1,000 to 4,000 in the half hour.

    Time presses, and I must again leave to a note what lies between Sydenham and the year 1707. Here we come abruptly upon a notable book by Sir John Floyer, Knt. It is called the “Physicians’s Pulse Watch.” He dedicates the first volume to Queen Anne, “for without health,” he says, “we should have no relish even for the extraordinary blessings of your reign.”

    He tells us in his preface, “I have for many years tried pulses by the minute in common watches and pendulum clocks and then used the sea-minute glass” such as was employed to test the log.

    At last he was more happy. One Daniel Quare, a Quaker, had in the last years of the seventeenth century put on watches what Floyer called a middle finger, as we say a hand.

    Floyer’s pulse watch ran sixty seconds and, you may like to know, can be had of Mr. Samuel Watson, in Long Acre. He tests this and a half-minute watch which has a cover by his sand-glass, and finds them not quite correct; one must add, he thinks, five beats.

    And now follow pulses of age and youth, pregnancy, exercise, sleep. And we learn how diet, blisters and the weather affect the pulse. Like a good everyday practitioner, he has his fling at science in the shape of a remark on the failure of Harvey’s discovery to influence medical practice. Nevertheless, the book, on the whole, is full of good observations thoughtfully carried out. For the first time in medical literature we meet with tabulated results; in fact, there is a modern air about his methods. Clearly he was a shrewd practitioner, a man of scientific accuracy, and knew the world; for he predicts, alas! too truly, that this new method will be sneered at and neglected. As late as 1768, Bordeu dismisses Floyer with something like contempt, and Fouquet qualifies all pulse-numeration as a mere useless curiosity, and sphygmometric instruments as idle toys. Falconer, as late in the century as 1796, says, “Floyer’s methods were unused until now.” And this was nearly true. In the eighteenth century one finds now and then a pulse count, as when Morgagni describes a pulse which beat twenty-two times in the sixtieth of an hour.

    If, indeed, any man wishes to nourish a taste for cynical criticism, let him study honestly the books of the eighteenth century on the pulse down to Heberden and Falconer, or even beyond them. It is observation gone minutely mad; a whole Lilliput of symptoms; an exasperating waste of human intelligence. I know few more dreary deserts in medical literature, from the essay on the Chinese Art of Feeling the Pulse, with which Floyer loaded his otherwise valuable essay, to Marquet’s method of learning to know the pulse by musical notes, an art in which he was not alone. And error died hard. The doctrine of the specific pulses, a pulse for every malady, although rejected by De Haen, is in countless volumes, and survived up to 1827, when Rucco dedicates his book on the pulse to Sir Henry Halford. Meanwhile whole volumes, like Bryce on Asthma, exist without a pulse or breath count; but further back, in a queer book on the heart by Bryan Robinson, I find the first clear statement of the proportional relation of the pulse to respiration. Even those among you given to reading the authors of the end of the last and the first twenty years of the present century, may be surprised to learn that statements of the numbers of pulse and respiration are very rare in Rush, Cullen and their contemporaries. Heberden and Falconer, who, perhaps, set too much value on pulse counts, made no impression on their contemporaries. In Corvisart on the Heart we hear little or nothing in this direction, and in seven hundred pages of Laennec there is one pulse count and no numeration of the breathing. It seems incredible, but not until the later French school developed its force do we find in reports of cases the beginnings of those systematic numerations of the breath and pulse which are met with in modern cases.

    If German science had been as much the fashion as German literature, the remarkable pulse studies of Nick, 1826, would have sooner wrought a change; but it was not until a later day, and under the influence of the great Dublin school, that the familiar figure of the doctor, watch in hand, came to be commonplace.

    I have thought it well to illustrate thus fully the medical history of the watch as an instrument of precision. How small, but how essential a part of pulse study are the numerations it enables us to make accurately, you all well know. We could better lose this knowledge than the rest of what the pulse teaches, and yet it is the only pulse sign we can put on paper with perfect precision, as Heberden remarked a hundred years ago.

    I have kept you long, and I fear may have been wearisome, but this tale of growth of Precision in Medicine is not without its moral. In every modern century were men who sought to secure it. The true rate of advance of medicine is, however, not to be tested by the work of single men, but by the practical capacity of the mass. The truer test of national medical progress is what the country doctor is. How useful, how simple, it seemed, to count the pulse and respiration, or to put a thermometer under the tongue, and yet it took in the one case a century, and in another far more, before the mass of the profession learned to profit by the wisdom of the few.

    A certain sadness surrounds these stories of medical discovery. I have resisted the temptation to tell you more of Currie’s notable essay, and of what little notice it won until Hufeland saw and proclaimed its value. The fate of Avenbrugger, the inventor of percussion, and of his little book, so small, so terse, so wonderful, is yet more pitiful. He foresaw its future and his own, saying in his preface (1760): “Enim vero invidiae, livoris, odii, obtrectationis, et ipsarum calumniarum socii, nunquam defuerunt viris illis, qui scientias et artes suis inventis aut illustrarunt aut perfecerunt.”

    Avenbrugger lived on to see his famous colleague, De Haen, write his fifteen volumes without a word on percussion. Van Swieten did it no greater justice. In his huge history of medicine, Sprengel mildly mentions it as rather subtle. Yet were the contents of this booklet of twenty-two pages more practically valuable to man than all these men wrote, or all the results of the vast and bloody campaigns during which it slept, until in 1808, one year before the grave, contented German died at 87, Corvisart translated it into French, and proclaimed its undying value to a waiting world.

    And now I have done. It seems to me, as I reflect on what I have said, that I have told you a long story of neglected inventions or discoveries, ending sadly in repeated failures to make on their time any permanent impression of the real usefulness of the work accomplished. It is not only the poet who has to wait, and may never see the morning light of recognition break upon his genius.

    In my mental wanderings amongst these numberless essays—these great folios—which are too often but splendid monuments, enclosing dead and forgotten thought, I have seen how strong was the resurrective force which now and then existed in some little essay long neglected; how from it, as from seed, arose in after-years a fresh growth of vitalizing thought, and how this story repeats itself over and over, until, at last, what one knew and valued becomes the riches of all.

    Assuredly in our day this process is more speedy than in the distant past. But be this true or not, there must be many among you who know that apart from large human acceptance, and the material compensations of professional success, there is that in the mere pursuit of truth which mysteriously rewards from day to day. This can no public or personal lack of recognition destroy, no indifference affect. I doubt not that such consciousness of duty done must have sustained many of the men whose failures to see their work result in larger use oppresses one who reads the story of medical discovery. Over and over, they predict their own failure to influence their fellows. The poet is grieved by the indifference of his contemporaries, but the physician seems to be made philosophical by the steadying influence of everyday work, so that not Marcus Aurelius could have been more content than Avenbrugger, whilst a half century passed by half scornful, and would not see the royal gift he offered to mankind. I am glad to think he was happy, and to know that for all of us, as for him, this incessant everyday work is a talisman of content, a fact which none know better than those to whom I now say, at last, my thanks and my farewell.

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