Recreating the Pulsilogium of Santorio: Outlines for a Historically-Engaged Endeavour

Fabrizio Bigotti, David Taylor and Joanne Welsman

Abstract tis medicis (‘On Medical Instruments’): a Between 2015 and 2016 a series of seminars task that, unfortunately, he was not able to on the history of early modern technology accomplish during his life. Consequently, and medicine were held at the Centres for many descriptions related to his instru- Medical History and Biomedical Modelling ments are partial or too general. Moreover, and Analysis of the University of Exeter. As previous attempts at reconstructions have a result of that work we laid down the basis subsequently been found to be either not for the first historically accurate reconstruc- historically informed or in some cases com- tion of a seventeenth-century instrument, pletely misleading. From this standpoint, the pulsilogium of Sanctorius (1561-1636). the reconstruction of Santorio’s instru- Previous copies were in fact either simple ments represents an essential task for any models for display or lacked any commit- historian or philosopher of science. ment to historical accuracy. This short Relying on a new assessment of Santorio’s contribution explores some of the results works as a whole, as well as on experimen- we obtained from the recreation of this de- tation and in some cases on new documen- vice and experiments we recreated which tary proofs, we were able to define some shed new light on the early application of key principles that laid down the basis for the as a scientific instrument. A the first historically accurate reconstruc- fuller and much more detailed account of tion of Santorio’s pulsilogium (Fig 2a-b). these discoveries will be given in a forth- coming contribution edited by Filip Buyse 1.1 Background for a special issue of the Journal of Social Experiences with, or referring to the pen- and Political Science. dulum, have a long history in science, being notably witnessed in the works of Nicole 1. Santorio and the Emergence of Fig. 1 Santorio Santori (1561-1636). Opera Omnia Oresme (1320-1382), Giovanni Marliani Early Modern Science Portrait from the in four th volumes ( 1660). (end of 15 century), Leonardo da Vinci The emergence of modern science be- (1452-1519), Gerolamo Cardano (1501- tween the sixteenth and seventeenth cen- 1576), and Giovanni Battista Benedetti tury had in medicine an important field of mention and possible application occurs in (1530-1590).1 Galileo’s famous studies on development, thanks especially to the work 1602 as part of a book on the (De pul- the pendulum, started at around the ninth of Santorio Santori (1561-1636) (Fig. 1). sibus) written by a colleague of Santorio in decade of the sixteenth century, would not Padua. It probably constituted a source of lead to any serious outcome until well after Mostly known for his contribution to the inspiration for, rather than being an inven- 1602. Galileo himself, in fact, seems not to study of , Santorio developed tion by Galileo, and sparked an entire path be making any practical use of such a de- or invented several types of instruments, of experiments in seventeenth-century vice up to the time of publication of his among which was a device named pulsi- Europe. Santorio presented his inventions Discorsi e dimostrazioni matematiche logium (literally: ‘an instrument that mea- as rough engravings in his Commentaria intorno a due nuove scienze (‘Two new sures the pulse’) which represents the first in Primam Fen Primi Libri Canonis Avi- sciences’, 1638). application of the pendulum to cennae (‘Commentary to the Canon of and the first instrument of precision in the Avicenna’ - Venice 1625) promising soon to Like Galileo, contemporary astronomers history of medicine. The earliest known publish another book called De instrumen- and physicians were concerned with the

Fig. 2a-b David Taylor and the Recreation of ‘Pulsilogium A2’ (January 2016).

30 Bulletin of the Scientific Instrument Society No. 133 (2017) devices of increasingly complex design meant to convert vital parameters into mea- sure (see Figs 4-8), which for our purpose we have classified according to letters and numbers [table 1]. In his first description – dated 1603 – Santorio states that an in- strument he invented and which he called pulsilogium was able ‘to show all the dif- ferences in equal movements’ that is to say that it could mark equal intervals of time.3 Although, it was only in 1625 that Santorio would reveal that such an instrument was pendulum regulated, there can be little doubt that it was the same instrument used by him since 1602. Even though the exact theoretical path lying behind Santorio’s studies on the pendulum remains uncer- tain, Santorio’s remarks prove that he had identified correctly the fundamental prop- erty of the pendulum which allowed him to painstakingly collect, record and com- pare various data resulting from the mea- surement of the pulse. In the simplest of his devices (Fig. 4), by suspending a leaden ball over a graduated bar, the physician had only to synchronise the swing of the pen- dulum with the frequency of the pulse, take note of the result and subsequently com- pare it with previous records. In a slightly improved version of the same device (Fig. 5) the same measurement is achieved by using a horizontal beam at one end of which a tapered peg controls movement of the linen thread; a small wooden bead fixed to the thread indirectly indicates pendulum length on a scale engraved onto the beam. Santorio or Galileo? All the scholars who dealt with Galileo and his studies on motion, simply assumed that Santorio’s pulsilogium was a direct outcome of the former’s research into the properties of the pendulum. Unfortunately, Fig. 3 Quadrans Muralis seu Tichonicus from Brahe, Astronomiae instauratae mechanica there are many major problems with this (Nuremberg 1602). hypothesis. The most important of which is

Table 1 problem of attaining an exact measurement at rest.2 Such a calculation, however, is not of time. pursued by adopting any precision device and accordingly it fails to consider fluc- In the frontispiece of his Astronomiae in- tuations of the pulse frequency that are a stauratae mechanica (Nuremberg 1602), consequence of the slightest change due to for instance, Tycho Brahe (1546-1601) dis- environmental factors and/or psychologi- plays his endeavours to obtain a precise cal conditions in the patient. The solution value of the time elapsed in his astronomi- to this problem came, much earlier, from cal observations by measuring and register- the field of medicine and was due to the ing the results provided by three different work of the Italian physician Santorio San- types of wall clock in attempts to compen- tori (1561-1636). sate for the notorious lack of reliability of mechanical devices (Fig. 3). Unlike Brahe, 2. Functioning and Purpose Johannes Kepler (1571-1630) still consid- At first Santorio seemed to introduce the ered the pulse’s record as a reliable time- pendulum to discriminate between regu- keeper for astronomical observations, and larity and irregularity and record the pulse tried to assess the number of pulse strokes frequency. For this he invented a series of per minute by using those of a healthy man

Bulletin of the Scientific Instrument Society No. 133 (2017) 31 Fig. 5 Pulsilogium Type A2. Fig. 6 Pulsilogium Type B1.

Fig. 4 Pulsilogium Type A1.

Fig. 7 Pulsilogium Type B2. Fig. 8 Pulsilogium Type C. that it takes no account of Santorio’s words in Santorio’s account a year later. In 1603, 1607), but does not suggest any practical and further assumes the primacy of Gali- in fact, Santorio published his own descrip- application for it, as – and this is essential leo’s over Santorio’s studies that is histori- tion which revealed that he had already to our understanding of Galileo’s studies – cally groundless. had enough time to experiment exten- he had not found a mathematical proof for sively with his instruments and had found the isochronism of the pendulum. He refers In his research, Dr Bigotti found that the at least 133 specific differences related to having performed experiments (esper- first quote referring to Santorio’spulsilo - to the pulse, a detail that – coupled with ienze) and describes a mere mechanical ex- gium was published in Padua in 1602 at Rudio’s description – suggests a much ear- planation (senza trasgredire i termini del- the time in which Galileo was teaching lier development of the pulsilogium, pos- la meccanica) for his observations.4 In all mathematics there. The book, published by sibly between 1590 and 1600. Galileo, on likelihood, Galileo’s experiments were re- a colleague of Santorio, the physician Eu- the other hand, refers to his experiments awakened by Rudio’s announcement of the stachio Rudio from Belluno (1548-1612) an- on the pendulum in a letter dated Novem- new possibilities opened up by Santorio’s nounced the creation of an instrument by ber 1602 to Guidobaldo del Monte (1545- invention although the latter, in turn, had Santorio in a few words that are amplified

32 Bulletin of the Scientific Instrument Society No. 133 (2017) certainly benefited from the meetings held torio further specifies that unaided by use ticing, however, that for the sake of in Venice and Padua at the circles of Gian of his pulsilogium such a variation can be medical diagnosis, a direct reading Vincenzo Pinelli (1535-1601) and Andrea so small that even a well-trained physician was also useless and could remain Morosini (1558-1618), which Galileo also can fail to perceive it, thus getting a terribly unknown to the physician: the exact partook and many mathematical arguments wrong diagnosis. record of the degree is for all prac- were discussed. As a final point, whilst Gali- tical purposes a sufficiently reliable Santorio’s appreciation of quantita- leo never personally claimed the invention means of monitoring the inclination tive values associated with physi- of such an instrument – it was indeed his towards health or sickness in each ological/pathological conditions is disciple Vincenzo Viviani (1622-1703) who patient. particularly relevant as it indicates claimed it on behalf of him some fifty years that this physician sought after ob- Whether by means of the pulsilogium San- later – Santorio openly ascribed that inven- jective criteria and understood the torio pursued an analysis of his patients tion to himself in all his works. All the early various conditions of the body as dy- grouping them by typology (melancholic, historical records found on experimenta- namic states varying within a range bilious, choleric, phlegmatic constitution) tion linked to the pulsilogium – most no- (latitudo) susceptible to measure- remains unclear, yet his constant use of the tably the experiments of Isaac Beeckman ment. plural for referring to his subjects (sani/ae- (1588-1637) on the pendulum and Peter gri homines) is possibly revealing of such Lauremberg’s (1585-1639) replica of this Inasmuch as measuring the degree of the an eventuality. What we can take for grant- device – acknowledge Santorio as its inven- pulse, or rather its latitude, is something ed however is the fact that experiments tor. Finally, it must be remarked that: different from measuring directly the pulse with the pulsilogium were repeated, due rate, the kind of measurement Santorio was The invention of the pulsilogium per- to the chiefly comparative use of the instru- capable of achieving with his instrument fectly fits in Santorio’s programme for ment: indeed Santorio used it to define the needs some further explanation – in par- quantification in physiology and with range of the normal/physiological activity ticular his use of terms such as ‘distance’ the invention of other instruments, of the body which entails a painstaking and and ‘degree’. such as and hygrom- repeated measurement of the pulse, over eters, following a threefold method of The terminology stretches back to the scho- long periods of time and under different empirical analysis as: lastic theory of the ‘latitude of forms’ (lati- environmental conditions. tudo formarum) that had a long-lasting a) measurement of a physiological 3. Preparations for the Replica process through definite param- tradition in medicine where – from eters; onwards – the concept of degree was piv- In preparation for our replica we collected otal in understanding the action of drugs and carefully analysed Santorio’s writings b) designing and manufacturing devic- and temperaments on the body. In keep- and compared them with the available rep- es to use to guarantee certainty in ing with both of these theories (degrees licas in various museums of Europe. Discus- measurement; and latitude), Santorio regarded the normal sion of the historical references took place c) essential part of repeated and con- activity of a body as a series of qualitative also in the form of public seminars organ- trolled experimentation. changes comprehended between a mini- ised by Dr Jo Welsman (Centre for Biomedi- cal Modelling and Analysis – Exeter). In its Regrettably, the hypothesis of Santorio’s mum and maximum of intensity that could final form, the instrument – based on the dependence on Galileo’s studies led schol- be measured by means of an incremental best-known model depicted in 1625 which ars to completely neglect the direct read- scale of degrees. It is worth noticing that, we defined in our general classification as ing of Santorio’s works, notoriously bulky before Santorio, the degree of intensity re- A2 – was the result of two rather intense but nonetheless revealing of a different ap- lated to each state was proportional to the years of research by Fabrizio Bigotti and proach to the use of the pendulum. individual under scrutiny thus being com- pletely arbitrary. David Taylor, spent in analysing materials, What Does the Pulsilogium scale, reliability and limitations of the in- Measure? One of the major scientific achieve- strument and, for each modification or im- ments of Santorio, in the history of provement, discussing the overall concept According to the statements we have col- science and ideas, was the ability to lected from Santorio’s works and other his- of measurement underpinning the new so- convert the concept of degree into lution adopted. torical testimonies, the pulsilogium is in- a quantitative value by means of in- tended to measure ‘the quantity’ or ‘the de- struments devised for the purpose. Materials have been carefully chosen by gree of distance’ (quantitas/gradus reces- relying on contemporary documentation sus dimetiri) of the pulse rate, that is to say As shown above, the pulsilogium fits exact- of Venetian furniture and, although not di- its variation in healthy or unhealthy condi- ly within this framework. As we will show rectly affecting the isochronous swing of tions. Such distance (recessus) spans from a in another contribution, the fact that the the pendulum, dimensions of the oscillat- minimum to a maximum of frequency as disposition of degrees in the pulsilogium ing ball received considerable attention as well as intensity which, in reference to the is consecutive, the measurement linear and well. Allowing that the pulsilogium could latter, Santorio – and all Renaissance phy- the difference between the minimum and be used also as a portable instrument, sicians – called ‘range of health’ (latitudo maximum results in 80 degrees (see Fig. the adoption of heavy and bulky material sanitatis). The pulsilogium seems to have 4), are not casual details, they highlight the would have been unlikely. As such, David been used chiefly as a comparator: Santo- fact that: Taylor suggested that Santorio’s original rio compared different segments of chord a direct reading of the pulse frequen- most probably used a musket ball as its related to the increase or decrease of the cy in beats per minute would not be pendulum bob. This suggestion was based pulse rate in terms of a rapport between possible, as the pulsilogium only al- on archaeological evidence of musket shot degrees. He adopted the device as espe- lows the user to explore it in terms in use in 17th century Europe, and on the cially revealing of the variation of pulse fre- of linear progression. It is worth no- relative scale of components in the wood- quency in fevers and other symptoms. San-

Bulletin of the Scientific Instrument Society No. 133 (2017) 33 cut image (see Fig. 5). However, to comply the pulse rate of a third one (the patient) imental physiology. with the current Health and Safety regula- and record the measurement obtained. As tions - in particular with COSHH (Control expected, a slight increase or decrease of Acknowledgements of Substances Hazardous to Health) and pulse rate due to environmental or psy- The archival research on Santorio’s instru- CLAW (Control of Lead at Work) – rather chological factors in the ‘patient’ was seen, ments was originally supported by the than lead, as in Santorio’s original descrip- overall however, it turned out that the dif- SIS Grant awarded in 2014 to Dr Fabrizio tion, we were constrained to use iron or ference in measurement was negligible and Bigotti and has been supported thereaf- brass as its material. almost exclusively attributable to the abil- ter by the Wellcome Trust as part of a ma- ity of each observer. jor project on quantification in medicine Scale units and measurement resolution aimed at classifying, understanding and were pivotal to understand the functioning Conclusions recreating all of Santorio’s instruments for and application of the pulsilogium, and to When we originally began our research and physiological and physical measurement this very aspect – which seems to have pre- experiments into Santorio’s pulsilogium, (106580/Z/14/Z). The reconstruction of vented scholars from achieving any positive the common opinion according to which, Santorio’s Pulsilogium (Type A2), however, result about Santorio’s methods hitherto – in his early years in Pisa while studying is very much a team effort and was part of we devoted most of our energies. The final medicine, Galileo had invented an instru- the engaged research project The Labora- outcome of our research will be presented ment to allow the exact record of the pulse tory of Santorio held at the University of and discussed at length in the forthcom- frequency, was still standing. As one result Exeter – Centres for Medical History and ing volume Oscillating Pendulum and the of our research, this view, already debated Biomedical Modelling and Analysis, which swinging philosophy of the seventeenth but never seriously challenged by histori- was generously supported by a Wellcome century a special issue of the Journal of ans, can now be dismissed. Our recreation Trust Institutional Strategic Support Award Social and Political Science edited by Filip of Santorio’s pulsilogium A2 demonstrates [WT105618MA]. Finally, we would like Buyse. For readers of the ‘SIS Bulletin’ we that the first technological application of to express our gratitude to Prof. Jonathan can nevertheless anticipate that, after much the pendulum is due to Santorio and it was Barry, Co-director of the Centre for Medical discussion on how to approach the ques- already known before 1602. As a medical History, for his constant and unconditioned tion, the ultimate answer came from the instrument the pulsilogium allowed physi- support throughout the project duration. descriptions we collected, and especially cians to record the ‘latitude of the pulse’, from the fact that all of Santorio’s instru- not its exact frequency in terms of beats Notes ments deal with equal intervals of ten divi- per minute, that is to say the range of varia- 1. A comprehensive history of the use of sions over a linear scale. tion of the pulse in both normal or patho- the pendulum before Galileo is still missing. Similarly, dimensions of the beam in the logical condition and so to compare data For a general overview the reader could pulsilogium A2 was an unknown that we collected over time. Combined with other consult Renn 2001 and Büttner 2008. strove to understand and solve. The prob- historical evidences that will be discussed 2. Kepler 1618, vol. I, bk 3, ch. 3, pp. 278- lem was tied up with the overall measure- in the forthcoming contribution, our re- 279: ‘In homine valente, robusto et perfec- ment resolution of the instrument and the search refutes the direct involvement of tae aetatis, complexionis melancholicae physiological range of its application; that Galileo in the creation of the pulsilogium aut consenescente fere singulis secundis being the case we decided to start from and places its development in the context existunt singuli pulsus arteriae (60o), nullo normal range of 60 to 100 beats per minute, of late Aristotelian physics, whereby mo- discrimine inter systolen et diastolen: ita the device being used by Santorio especial- tion and velocity were measured not in essent in uno minuto pulsus sexaginta; sed ly to assess the physiological conditions of terms of rapports between magnitudes - as rara est haec tarditas, vulgariter numerantur the body. The resulting overall length of the Galileo will do much later - but in terms of 70, in cholericis et feminis 80, quatuor in instrument scale is then 64.3cm, adding the degrees that were added or subtracted by terna secunda. Breviter in una hora quatuor space required to fit the tapered peg and an already known quantity. Indeed, with millia plus minus’. other components the overall beam length the pulsilogium of Santorio we are still 3. Santorio 1603: 109rD-109vB. comes out at about 76cm. These aspects in an intermediate phase in which natural 4. Drake 1979: pp. 69-71. and others related to Santorio’s improve- philosophy was crossing the boundaries ments on different models of pulsilogia of the abstract generalisation provided by References the medieval physics to access the realm of will be explored and discussed in the forth- Bedini 1991: Silvio A. Bedini, The Pulse of number and quantification; a phase which coming contribution. the Time. , the determination represents the essential pre-requisite of of longitude, and the pendulum clock (Flor- 3.1. How Reliable is a Pulsilogium? Galileo’s studies, not their outcome. Such ence: Leo S. Olshcki Editore, 1991). How reliable was the pulsilogium in terms a transition was first made within the con- of actual measurements? This question was text of Late Renaissance medicine and natu- Büttner 2008: Iochen Büttner, The Pen- addressed in a series of experiments con- ral philosophy in a moment in which a new dulum as a Challenging Object in Early ducted by Dr Joanne Welsman and David approach to nature was shaped. Thus, one Modern Mechanics, in Walter Roy Laird Taylor at the South Devon University Tech- of the major outcomes of our research is and Sophie Roux (Eds), Mechanics and nical College of Newton Abbot (UK). Stu- that it potentially provides a new insight on Natural Philosophy before the Scientific dents with no background in early modern the concept of quantification in medicine Revolution (Dordrecht: Springer, 2008), pp. medicine, were asked to carry out measure- and, most notably, on the functioning of 223-238. ments using replicas of Santorio’s pulsilogi- early modern technology: Santorio’s pulsi- Castiglioni 1920: Arturo Castiglioni, La vita um A2. Measurements were taken in a kind logium marks not only the opening era of e l’opera di Capodi- of doctor patient session, whereby two precision instruments in early modern sci- striano (Bologna: Licinio Cappelli, 1920). different students (doctors) were asked to ence, but represents the first fundamental Caverni 1891-1900: Raffaello Caverni, Sto- use replicas of pulsilogium A2 to match step towards the shaping of modern exper- ria del Metodo Sperimentale in Italia

34 Bulletin of the Scientific Instrument Society No. 133 (2017) (Florence: Stabilimento G. Civelli Editore, Continued from page 29 1891-1900). Drake 1969: Stillmann Drake, ‘Galileo’s very slightly larger than the drill sizes if 1604 Fragment on Falling Bodies’, The Brit- measured accurately. ish Journal for the History of Science, 4-4 (1969), pp. 340-358. No inch mm 74 0.0225 0.57 Drake 1979: Stillmann Drake, Galileo at 72 0.025 0.64 Work. His Scientific Biography (Chicago 70 0.028 0.71 and London: The University of Chicago 68 0.031 0.79 Press, 1979). 66 0.033 0.84 Ettari-Procopio 1968: Maria Stella Ettari and 64 0.036 0.91 Marco Procopio, Santorio Santorio. La Vita 62 0.038 0.97 e le Opere (Rome: Istituto Nazionale della 60 0.040 1.02 Nutrizione, 1968). 58 0.042 1.07 Grmek 1952: Mirko Drazen Grmek, Santo- 56 0.0465 1.18 rio Santorio. Njegovi aparati i instrumen- 54 0.055 1.40 ti (Zagreb: Institut Za Medicinska Istrazi- 52 0.0635 1.61 vanja Jugoslavenske Adamije, 1952). I have a few queries however which Kaare Grmek 1990: Mirko Drazen Grmek, La Pre- Hendrum might care to answer: mière Révolution Biologique. Réflexions Fig. 4 The mystery lithographic stone sur la Physiologie et la Médicine du XVIIe 1. Is the blade a round spike or is it a flat siecle (Paris: Payot, 1990). lancet shape? sume the drawings are simply generic rep- Kepler 1618: Johannes Kepler, Epitomes As- 2. Does the top end of the punch give any resentations of eighteenth-century instru- tronomiae Copernicanae (Linz, 1618). indication whether it has been depressed ments. However, the equatorial telescope, by hand or does it look as if it has been Renn 2001: Jürgen Renn, Galileo in Con- Fig. 5, in the lower right corner of the struck with a hammer? text (Cambridge: Cambrdige University stone caught my attention as a depiction Press, 2001). If my guess is right then the plate would of Ramsden’s equatorial, as illustrated on Santorio 1603: Santorio Santori, Methodi Vi- have been aligned with the hole, of the drill the folding plate, Fig. 6, from his pamphlet tandorum Errorum Omnium qui in Arte size to be used, aligned over the point to ‘Description of a new Universal Equatoreal Medica Contingunt Libri XV (Venice: Fran- be drilled. The two small end holes could (sic), made by Ramsden, with the method cesco Bariletto, 1603). then have been used to pin it in position. of adjusting it for observation,’ dated May Santorio 1625: Santorio Santori, Commen- The punch could have been placed care- 1774. With that discovery, I looked closer taria In Primam Fen Primi Libri Canonis fully over the hole in the plate and activat- at some of the other instruments on the Avicennae (Venice: Giacomo Sarcina 1625). ing it would have pulled it directly into stone. The large theodolite in the lower left the centre of the plate hole and punched corner of the stone matches the instrument Santorio 1660: Santorio Santori, Opera Om- the workpiece below. The drill would then on p. 149 in J. A. Bennett’s The Divided Cir- nia Quattuor Tomis Distincta (Venice: have been simply run through the plate cle (Oxford, 1987), taken from a plate in Francesco Brogiolo, 1660). into the workpiece with the punched mark George Adams’s Geometrical and Graphi- Weir-Mitchell 1892: Silas Weir-Mitchell, The stopping the drill from wandering. cal Essays (London, 1791). Perhaps other Early History of Experimental Precision drawings on the stone can be matched so Incidentally a company of toolmakers in Medicine (New Haven: Tuttle, More- closely as these two. Based upon the dating called Tyzack had an ‘Elephant’ brand of house and Taylor Printers, 1892). of the instruments, it seems likely that the tools.’ Authors addresses: stone was used to illustrate an early nine- Dr Fabrizio Bigotti (Leading author) Object 7 teenth-century encyclopaedic work, which Centre for Medical History Member Ronald K. Smeltzer, a long-time remains to be identified. Can you identify University of Exeter book collector about historic scientific in- the work? email: [email protected] struments and other scientific topics, recently acquired the David Taylor lithographic printing stone il- Mantracourt Electronics Ltd., Exeter lustrated in Fig. 4. Not exactly email: [email protected] rectangular, the dimensions are about 32.5 x 23.5 x 2 cm. The Dr Joanne Welsman text at the top reads from left to Centre for Biomedical Modelling and right as the stone would print: Analysis ‘Mathematik. Unterabth. Geometrie, University of Exeter Instrumente email: [email protected] Naturwissenschaft Nr. 14’ The stone has seventeen num- bered drawings of instruments. Fig. 5 The stone’s depiction Fig. 6 The stone’s depiction of At first thought, one might as- of Ramsden’s equatorial the same instrument. telescope.

Bulletin of the Scientific Instrument Society No. 133 (2017) 35