Von Helmholtz Research Articles

Principle of reciprocity solves the most important problems in bioimpedance and in general in bioelectromagnetism

Though the principle of reciprocity was invented by Hermann von Helmholtz already over 150 years ago, and though it is a very powerful tool in solving various important problems in bioelectromagnetism, it is not generally used. In impedance tomography the measurement sensitivity distribution has generally been misunderstood. This can be easily demonstrated with the principle of reciprocity. Some other applications of the principle of reciprocity are also discussed.

Hermann von Helmholtz: A 19th Century Renaissance Man

Hermann von Helmholtz was many things to many people: physicist, teacher, medical doctor, aesthete and more. He drew on his extensive knowledge of many fields to invent the ophthalmoscope-a device that revolutionized ophthalmology-when he was just 29 years old.

Notes on Contributors

Notes on Contributors

Helmholtz's early empiricism and the Erhaltung der Kraft

Summary Hermann Helmholtz has often been understood to have started research under the influence of Kant, and then to have made a transition to a later mature empiricist phase. Without claiming that in 1847 Helmholtz held the same positions that he later espoused, I suggest that already in his 1847 ‘Über die Erhaltung der Kraft’ one may find important aspects of his later empiricism. I highlight the ways in which, from early on, Helmholtz turned Kant to use in developing an empirical program of inquiry into possible basic natural causes. To that end, I indicate how, throughout his arguments, Helmholtz employed, sometimes explicitly, but often tacitly, an empiricist logic, one that ran contrary to any form of transcendental deduction, and even to all a priori knowledge. Instead of deriving aspects about the ultimate constituents of nature, Helmholtz aimed to define the proper project for physical natural science. The first part of the paper describes the context of discussion in which Helmholtz entered. The bulk of the paper then analyzes Helmholtz's arguments in order to make space between (1) Kantian, and other, deductions of characteristics that must be true of nature and (2) Helmholtz's delineation of empirically determinable characteristics of presumed ultimate elements of nature, ones that he meant to be specified and delimited through future experimental research. The paper highlights that throughout his discussion Helmholtz meant to define the proper project for physical natural science, a project rife with empiricist aspects.

From the Leiden jar to the discovery of the glass electrode by Max Cremer

The discovery of the glass electrode by Max Cremer was possible because of the advances made in the nineteenth century in understanding the electrical properties of glass, and because of the studies of electrical potential drops at the interface of phases. The discovery of the Leiden jar by E. G. von Kleist and the follow-up studies of the properties of that capacitor disclosed that glass is a dielectric. Much later, the ionic conductivity of glass was noticed and studied by J. H. Buff, W. von Beetz, W. Thomson (Baron Kelvin of Largs), W. Giese, H. L. F. von Helmholtz, E. Warburg, etc. It needed also the discovery of electromotive forces due to the partition of mobile ions (charge separation) by W. Nernst and E. H. Riesenfeld to pave the way for the idea that ion partition also occurs at solid–solution interfaces producing electromotive forces (emf). At the beginning of the twentieth century, the ground was laid to expect that a very thin glass membrane may produce an electromotive force because the glass has a finite ionic conductivity and ion partition may cause an emf. It obviously needed a physiologist like Max Cremer who desired to mimic a cell membrane (a semipermeable membrane), to use a glass membrane for that purpose. Cremer’s congenial choice of a thin glass bulb was rooted in a thorough understanding of the origin of electromotive forces, and it was not initiated directly by the Giese-Helmholtz cell, as some later reviews suggested. Later Cremer realized that an emf builds up when aqueous solutions are separated by a thin glass membrane. Cremer’s discovery was picked up by F. Haber who developed the glass electrode together with his PhD student Z. Klemensiewicz as an analytical tool. The following decades have brought improvements of the glasses and measuring techniques, and a deeper insight into the functioning of the glass electrode. Here, it will be shown that full credit for the discovery of the glass electrode effect must be given to Max Cremer. Unfortunately, his role has not been adequately described so far, mainly because Haber dominated the literature.

Science and Internationalism in Germany: Helmholtz, Du Bois-Reymond and Their Critics

In the wake of the Franco-Prussian war, scientific nationalism became a subject of scientific controversy in Germany. This paper explores the controversy between the cosmopolitan physiologists Hermann von Helmholtz and Emil du Bois-Reymond on the one hand, and the nationalistic economist-philosopher Eugen Duhring and the astrophysicist Johann Carl Friedrich Zollner on the other. It argues that Helmholtz' frequent visits to Britain helped him keep abreast of scientific developments there and shaped his ideas of science and society. They also changed his conception of the conservation of energy. German nationalists objected to his British contacts with offensive accusations. They alleged that he had plagiarized his fellow-German Julius Robert Mayer and tried to imitate British physicists. Thus Duhring and Zollner defended and constructed enduring national stereotypes of German and British science. Whereas Helmholtz put scientific cosmopolitanism into practice, Du Bois-Reymond defended it as an ideology. In contrast to the received view of Du Bois-Reymond as a fervent nationalist, it is argued that he was actually an untimely scientific cosmopolitan. He placed himself in the tradition of Goethe and Schiller's Weimar cosmopolitanism.

Helmholtz in Gilded-Age America: The International Electrical Congress of 1893 and the Relations of Science and Technology

Summary This essay recounts Hermann von Helmholtz's trip to represent Germany at the International Electrical Congress in Chicago in 1893 as well as his reception by various members of the American scientific, technological, and cultural elite in several other American cities. In doing so, it seeks to portray something of the vitality of the youthful and increasingly important American scientific community; of the strong relationship between American and German scientists, including how Helmholtz used and was used by them and various other members of the American elite to promote science and culture in America as well as to promote his own and German interests; and, finally, of what many considered to be the close interactions between science and technology in the late nineteenth century. In short, the essay seeks to use Helmholtz's trip to capture a sense of the broader relationship among science, the nation-state, and cultural elites in Gilded-Age America and between Germany and America.

The Wheatstone Concertina and Symmetrical Arrangements of Tonal Space

The English concertina, invented by the physicist Charles Wheatstone, enjoyed a modest popularity as a parlor and concert instrument in Victorian Britain. Wheatstone designed several button layouts for the concertina consisting of pitch lattices of interlaced fifths and thirds, which he described in patents of 1829 and 1844. Like the later tonal spaces of the German dualist theorists, the concertina's button layouts were inspired by the work of eighteenth-century mathematician Leonhard Euler, who used a lattice to show relationships among pitches in just intonation. Wheatstone originally tuned the concertina according to Euler's diatonic-chromatic genus before switching to meantone and ultimately equal temperament for his commercial instruments. Among members of the Royal Society, the concertina became an instrument for research on acoustics and temperament. Alexander Ellis, translator of Hermann von Helmholtz's On the Sensations of Tone, used the concertina as a demonstration tool in public lectures intended to popularize Helmholtz's acoustic theories. The English concertina's history reveals the peculiar fissures and overlaps between scientific and popular cultures, speculative harmonics and empirical acoustics, and music theory and musical practice in the mid-nineteenth century.

Details of the construction of perception: a closer look at illusory contours

Are we aware of neural activity in primary visual cortex? This question was asked in a classic paper written by Nobel laureate Francis Crick and Christof Koch more than a decade ago (Crick and Koch, 1995). By now, several studies have addressed the question, but so far consensus has not been reached (Rees, 2007; Tong, 2003). A recent study by Maertens et al. (2008) presents new relevant data on this issue. They demonstrated that activity in primary visual cortex (V1) is correlated with the perception of subjective contours. Maertens et al. used Kanizsa figures to induce a percept of illusory contours (IC, Figure ​Figure1),1), which are subjective in the sense that there is no actual change in luminance at the location of the perceived contour. Figure 1 Kanizsa stimuli used by Maertens et al. (2008). Illusory contours were generated by inducers (black “pack-men”) shown at different angles. The task was to judge whether the illusory contour was convex or concave. As control condition, ... The (illusory) perception of the contours is dependent on coherent orientation of the inducers. Hence, by either aligning or misaligning the inducers, very similar (local) physical parameters can create two subjectively different visual experiences. IC can therefore be used to provide information on neural correlates of conscious perception. An important feature of Maertens et al.’s experiment was the localization of neural activity specific for contour perception. This was accomplished by using spatially specific localizer stimuli for the contours and inducers separately, as well as by using a spatially more precise imaging sequence than traditionally used ones. This enabled the conclusion that the IC were related to retinotopically specific regions within V1, thereby extending previous research on IC where IC-related activity at such a level of detail was not observed. The results also add to existing evidence regarding V1 involvement in conscious perception. In previous research on conscious perception, some but not other studies have observed correlated activity in V1. A factor that could account for the inconsistent results is the specific task requirements. Specifically, it has been suggested that there is a reverse hierarchical sequence for conscious perception such that global, holistic features are perceived first and the details are added if required (Hochstein and Ahissar, 2002). In the Maertens et al. paper, the angle of the induced contrasts was varied between trials and the participant was required to judge the angle on each trial (Figure ​(Figure1).1). Hence, the task mandated a fine-scaled decision which required detail to be extracted – detail at such a fine scale that it may only be present in V1 due to its small receptive fields – and might therefore have induced correlated V1 activity. A hypothesis put forth by Crick and Koch in their 1995 paper was that, while activity in V1 may be necessary for conscious perception, it may not be sufficient. According to Crick and Koch, sensory regions need to be connected to prefrontal cortex to enable conscious perception. Whether involvement of frontal regions is necessary remains controversial (Eriksson et al., 2008), but a role of prefrontal cortex is indicated by a large number of neuroimaging studies showing a correlation between activity in frontal regions and conscious perception (Naghavi and Nyberg, 2005; Rees et al., 2002). In the Maertens et al. study, a limited part of the brain was sampled to improve spatial resolution. While this enabled the retinotopic mapping of the IC and thus constituted a great strength of study, this level of detail comes with a cost as nothing could be concluded regarding frontal involvement in the creation of IC. Future work, building on the methods used in the Maertens et al. study along with whole-brain sampling could shed light on the involvement of higher-order cortical regions and necessary vs. sufficient conditions for conscious perception. In sum, the Maertens et al. study is an excellent demonstration of the constructive nature of perception (von Helmholtz, 1910). Moreover, it shows that this constructive process is not confined to higher levels of the visual hierarchy, but can take place even at the lowest level of cortical processing.

Kant, Helmholtz, Riemann und der Ursprung der geometrischen Axiome

The essay attempts to discuss one more time the relationship between the positions of Immanuel Kant and Hermann von Helmholtz concerning the problem of space. First, it is pointed out that the fundamental problem of Kant's philosophy of geometry is to show that the congruence of geometric figures cannot be reduced to the logical identity of concepts. The notion of congruence, as the basic notion of Kant's theory of space, offers therefore a tertium comparationis, that allows to compare Kant's doctrine of space, with the development of geometry in the 19 th century, especially with Bernhard Riemann's approach. Helmholtz's philosophy of geometry, that starts precisely with a definition of congruence, in this way represents a historic and systematic mediation.

Signs, toy models, and the a priori: from Helmholtz to Wittgenstein

The Marburg neo-Kantians argue that Hermann von Helmholtz’s empiricist account of the a priori does not account for certain knowledge, since it is based on a psychological phenomenon, trust in the regularities of nature. They argue that Helmholtz’s account raises the ‘problem of validity’ ( Gültigkeitsproblem): how to establish a warranted claim that observed regularities are based on actual relations. I reconstruct Heinrich Hertz’s and Ludwig Wittgenstein’s Bild theoretic answer to the problem of validity: that scientists and philosophers can depict the necessary a priori constraints on states of affairs in a given system, and can establish whether these relations are actual relations in nature. The analysis of necessity within a system is a lasting contribution of the Bild theory. However, Hertz and Wittgenstein argue that the logical and mathematical sentences of a Bild are rules, tools for constructing relations, and the rules themselves are meaningless outside the theory. Carnap revises the argument for validity by attempting to give semantic rules for translation between frameworks. Russell and Quine object that pragmatics better accounts for the role of a priori reasoning in translating between frameworks. The conclusion of the tale, then, is a partial vindication of Helmholtz’s original account.

Stagnant vortex flow

With the aid of the vorticity transport equation it is shown that in inviscid, incompressible, axially symmetric vortex flow the axial vorticity component near the axis of the vortex approaches zero if the axial velocity component approaches a stagnation point, and vice versa, the axial vorticity component is increased, if the axial flow is accelerated. This result, obtained in earlier investigations by simplifying the momentum equations for the neighborhood of the axis of the vortex, is already contained in the vorticity transport equation as formulated by von Helmholtz in 1858. In laminar flow, with viscous forces acting near the stagnation point, the angular velocity does not necessarily vanish with the axial velocity component. These questions are discussed in the following.

A Simple Model for Teaching Postmortem Monocular Indirect Ophthalmoscopy

Although the ophthalmoscope was invented by Hermann von Helmholtz in 1851, pathologists until recently have relied almost exclusively on ocular enucleation to identify and describe postmortem fundal abnormalities. An inexpensive but valuable tool for forensic pathologists, the postmortem monocular indirect ophthalmoscope consists of a light source attached to a headband along with a hand-held lens. This permits a wide view of the fundus after death but the technique can be challenging to master for pathology residents and forensic pathology fellows. To facilitate skill acquisition in monocular indirect ophthalmoscopy, a simple and inexpensive teaching model can be constructed from hinged, cylindrical plastic containers. An artificial pupil created in the lid and a removable color fundal image placed in the bottom of the opaque container allows the pathologist-in-training to practice the technique of monocular indirect ophthalmoscopy and correctly identify, localize, and describe fundal abnormalities such as retinal hemorrhages.

Good Vibrations: "Sirens," Soundscapes, and Physiology

This article establishes Joyce's ongoing interest in psychoacoustics and illustrates how much he drew, in the writing of the "Sirens" episode, on nineteenth-century sound experiments that were developed by the German physician Hermann von Helmholtz. It argues that Joyce consciously referenced nineteenth-century sound theories to explore the link between the emotional and sensory experience of music and the physical and physiological components of sound perception.

Music psychology: The building of a community.

ABSTRACT-Although music psychology as a research topic can be traced back to at least the 1880s, it was not until the 1980s that it became an academic discipline with its own identity. The autobiographies in this issue describe the transformation of music psychology from a topic pursued by isolated individuals in many different disciplines, into a more unified field. The turning point for the field came in the 1980s and 1990s when there was a rapid growth of specialized venues for interdisciplinary research in music: journals, national and international conferences, national and international societies, institutes and centers for research, and educational programs. Research was disseminated as never before, connecting researchers all over the world and forming a community of music psychology practitioners who share a common set of methods and theories. This has resulted in the bringing together of formerly separate lines of research, for example, research on music and the brain has now become an important part of music psychology; the formation of educational programs where students can earn degrees in music psychology; the building of a historiography for the field; and an expansion of research topics to cover all major aspects of music. What defines an area of research as an academic discipline separate from related or parent disciplines? For music psychology an important part of the definition seems to be the existence of a community of researchers from disparate fields. The autobiographies in this issue describe the transformation of music psychology from a research topic pursued by isolated individuals in many different disciplines, into an academic discipline with its own identity. When and why did this transformation take place, and how has it changed research in music psychology? The contributors to this issue have addressed these questions through their own personal stories. As a research topic, music psychology can be traced to at least the 1880s in Germany and Austria. The work of Hermann von Helmholtz (a physicist, physician and physiologist) can be considered the start of empirical research in psychoacoustics and music perception, but there was also an avid interest in higher-order cognitive processing of music. Psychologists (such as Carl Stumpf) and systematic musicologists (for example, Richard Wallaschek) pursued philosophical, theoretical and sometimes empirical work in music cognition (Graziano & Johnson, 2006) . At the same time in late nineteenthcentury Germany, neurologists pursued a similar but completely separate research path investigating acquired impairments in music skill in order to map brain localization of music function (Johnson & Graziano, 2003; Johnson, Graziano, 8c Hayward, in press) . Although dialogue and exchanges of ideas took place between psychologists and musicologists, there were very few substantive interactions between physiologists, psychologists/musicologists and neurologists. These disconnected lines of research - music perception, music cognition, music and brain - continued throughout the twentieth century. As Lola Cuddy and Mari Jones mention, for most of the twentieth century, individual researchers in music were isolated within their specific disciplines. And then, for most of our contributors, it all started to change in the 1980s. During the 1980s and 1990s there was an explosion of activity, out of which emerged an academic discipline - music psychology. In his paper for this volume, Andrew Gregory describes John Sloboda's 1985 book, The Musical Mind, as a landmark publication. Sloboda's book combined a rigorous cognitive approach with an understanding of deeper musical factors; this combination stimulated music psychology research throughout Britain. Sloboda himself identifies the turning point for the field as the 1983 publication of Lerdahl and Jackendoffs Generative Theory of Tonal Music. This detailed, universal theory of musical structure sparked thinking, research, criticism and counter-theories, which have shaped music psychology as a field (Sloboda, 2005). …

Ophthalmology, Popular Physiology, and the Market Revolution in Vision, 1800–1850

It cannot have escaped the notice of every medical observer that an unusual prevalence of diseases of the eye marks the period in which we live. Indeed, they are so prevalent, that they may be considered one of its common and peculiar trials.Edward Reynolds, Hints to Students on the Use of the Eyes, 1835In America the purely practical side of science is cultivated admirably, and trouble is taken about the theoretical side immediately necessary to application.Alexis de Tocqueville, Democracy in America, 1835The scopic regime of modernity may best be understood as a contested terrain, rather than a harmoniously integrated complex of visual theories and practices.Martin Jay, Scopic Regimes of Modernity, 19881The practice of ophthalmology experienced tremendous growth in the first half of the nineteenth century. At least five eye hospitals opened in American cities between 1820 and 1850, offering venues for the practice of a burgeoning field of surgeons increasingly devoted to ophthalmic pursuits that included medicinal and surgical treatment, experimentation, publication, and the education of others. Outside this increasingly codified arena of practice, opticians, reform physiologists, and others concerned with matters of vision published a spate of treatises explaining in lay terms the eye's basic mechanisms and capacities. These works also instructed readers, already well versed in homespun methods of eye care, in diagnosing a wide range of ocular maladies and in caring for their eyes in order to maintain properly functioning sight, which had become crucial for navigating a cultural terrain significantly altered by market revolution.Amid vast technological, economic, and social change, new trades sprang up around the exchange of printed information - typesetters and printers, newspaper editors and journalists, clerks and copyists, to name but a few. But as this expanded culture of print proliferated, new perceptual problems loomed. As a result of the profusion of texts - printed ledgers and billheads, cheap newspapers and broadsides - and the dense visual nature of their myriad forms, antebellum culture registered the early stages of overstimulation, a phenomenon typically associated with the urban culture of the later nineteenth and early twentieth centuries. In response to this wave of new media, the viewing practices they formed, and the peculiar conditions of seeing in densely populated urban environments, ophthalmologists, opticians, reform physiologists, and their publics voiced a range of concerns regarding the toll these phenomena and practices were taking on human vision. Taken together, these constituents established standards and practices concerning the properties and maintenance of the eyes that delineated ways of seeing particular to this time and place. They suggested ways to defend the eyes against disease and debilitation and posited a model of vision that coalesced around the needs of production and consumption in the antebellum decades.The second half of the nineteenth century has been hailed as ophthalmology's golden age, initiated by Herman von Helmholtz's introduction of the ophthalmoscope and marked by increasing specialization, clinical sophistication, and institutional codification. The development of ophthalmology and the dissemination of ophthalmic principles in the first half of the century, however, situated them as integral segments of the social, cultural, and economic transformations that historians have associated with the market revolution. Ophthalmology's professional development in the early republic, set in relation to the growth and spread of reform physiology and other popular measures for maintaining properly functioning vision, illuminates the formation of ideas about the nature of vision and the changing status of observing subjects in ways that shed light on the role of this noblest of senses amid the new chaos of market life. …

A History of the Concept of the Stimulus and the Role it Played in the Neurosciences

The term stimulus, as it was used in science from its earliest appearance in the sixteenth century up to the beginning of the nineteenth century, shows a gradual progress in denotation from the physical object designed to produce nervous and muscular excitation to the generically conceived event or object that initiates sensory or motor activity. To this shift corresponds a shift in the understanding of sensory experience. Johannes Müller's law of specific energy of sensory nerves played a major role in the shift, and Hermann von Helmholtz gave the shift its most thorough philosophical explanation.

Tuning forks, resonators, and beats: Demonstrations for “Project Listen Up”.

Gearing to an audience of all ages, a demonstration apparatus is presented including student versions of Hermann von Helmholtz’s tuning fork sounder, circa 1859 (where an intermittent current in an electromagnetic coil drives the tuning fork, which is located near a resonator), and Alexander Graham Bell’s tuning fork experiment, circa 1876 (where a variable resistance circuit due to a slight tuning fork contact in a conductive liquid causes a relay to vibrate at the same frequency as the fork). Using the popularity of a basic mechanical acoustical apparatus and briefly unfolding the histories behind Helmholtz combining several of his tuning fork sounders to generate vowel sounds and Bell’s first telephone, students are then given careful explanations of the demonstrations. Next, the focus shifts to well developed basic experiments that students can perform in a laboratory setting with emphasis placed on presenting the details of a carefully thought out scientific approach. “Project Listen Up” (an initiative of the Education in Acoustics Committee) hopes to develop an educational apparatus for a broad range of learners as one of their goals. [Work supported by USNA.]

Tonpsychologie und Musikforschung als Katalysatoren wissenschaftlich‐experimenteller Praxis und der Methodenlehre im Kreis von Carl Stumpf

The study of acoustics, harmonics and of music has been providing scientific models since Greek Antiquity. Since the early modern ages, two separate cultures began to emerge out of the study of music: a technical acoustics and an aesthetically and philosophically inspired musical criticism. In the writings of Johann Friedrich Herbart (1811) a scientific approach to musical aesthetics and to music perception is taking shape that reinstalls the listening process as a highly complex and logical phenomenon. By opening music for a scientific psychological investigation, Herbart pioneered the physiologically and acoustically grounded seminal work by Hermann von Helmholtz On the sensations of tone (1863) which the author considered a prerequisite for musical aesthetics and music theory. Helmholtz in turn inspired the philosopher and psychologist Carl Stumpf to further investigate musical perception (beginning in 1883). To Stumpf, it provided a paradigm for experimental psychology as mental functions and phenomena could be studied in detail. These functions and phenomena are the actual objects of scientific study in Stumpf's inductive and descriptive psychology. Combining insights from statistics, ethnology, anthropology, psychoacoustics and the cultural history of mankind, Stumpf and his team developed a new blend of science which absorbs styles of reasoning, analytical procedures and academic convictions from natural history, the natural sciences and the humanities but at the same time identifies shortcomings of these approaches that fail to grasp the complexities of psychic functions. Despite their reliance on the quasi-objective phonograph and despite their commitment to objectivity, precision and measurement, mental phenomena relating to tonal perception and to music provided too complex a challenge to be easily articulated and shared by the scientific community after 1900. The essay illustrates these tensions against the background of a history of objectivity.

LIQUOR COTUNNII

Domenico Cotugno was a famous physician who lived in Naples in the 18th century. At the age of only 25 years, he published an important book on the anatomy of the inner ear that contained some theories concerning the physiology of hearing, the later developments of which were associated with the name of Hermann von Helmholtz. Three years later, he wrote a book on the physiopathological causes of sciatic pain, in which, for the first time in medical history, he differentiated true sciatic pain from the pain attributable to secondary causes. Using a series of meticulous dissections and elegant experiments, he showed that not only brain ventricles but also the subarachnoid spaces of the cranium and spine were filled with circulating fluid, which is why cerebrospinal fluid is also known as "liquor cotunnii."