Helmholtz’ Apparatuses Telegraphy as Working Model of Nerve Physiology Christoph Hoffmann Max-Planck-Institute for the History of Science, Berlin Introduction In Hermann von Helmholtz’ physiological writings the word ‘appara- tus’ can have several meanings. In his famous treatise Die Lehre von den Tonempfindungen als physiologische Grundlage für die Theorie der Musik (1863), for example, Helmholtz refers to at least three different apparatuses: the experimental “apparatus” used for producing single tones, the “apparatus belonging to the drum of the ear”, which consists of hammer, anvil, and stirrup connecting eardrum and labyrinth and, some pages later, the “termination of the auditory nerves” in Corti’s or- gan is characterized as a kind of “peculiar auxiliary apparatus” made for resonating [Helmholtz 1870, 178, 199, and 212]. The diverse use of the word was by no means unusual in the golden age of German ‘organic physics’ in the decades between 1845 and 1870 [Lenoir 1997, 75-95]. On the contrary the ubiquitous talk about apparatuses itself might be understood to constitute organic entities as physically defined techno- logical objects. As a consequence it could appear that it is only meant metaphorically, when Helmholtz talks about the several parts of the in- ner ear in terms of an apparatus. But if we understand metaphors with Philosophia Scientiæ, 7 (1), 2003, 129–149. 130 Christoph Hoffmann Hans Blumenberg mainly as “fossils that indicate an archaic stratum of the trial of theoretical curiosity” [Blumenberg 1979b, 82], then the per- spective shifts and what appears as an explanatory principle introduced ex post, turns out to be a remnant or sediment of the research process itself. In fact, since Xavier Bichat’s Anatomie générale (1801) physiol- ogists of the 19th Century not only distinguished some organic entities from others as apparatuses [Bichat 1801, I, XCIX]. First and foremost they investigated and determined characteristics of organic functions by means of apparatuses. With respect to Helmholtz’ work on the qualities of tone Timothy Lenoir has shown, how in the course of experiments telegraphic devices, sound forks and resonators were arranged as a “material model of the ear in reverse” [Lenoir 1994, 204]. What happened here and in a number of other physiological investigations of the period was that apparatuses or parts of them not only helped to carry out experiments and observa- tions. They were simultaneously perceived as representations or models of the research object itself. As Lenoir suggests, the experimental set-up Helmholtz used in his investigations did not simply allow him to arrange such a problematic research object as the qualities of tone. Within this set-up the process of sensation and the function of the ear in general became understandable in a new way: “The representation thus funda- mentally affected the articulation of theory.” [Lenoir 1994, 206]. Referring to scientific apparatuses and experimental set-ups as mod- els implies a substantial change of their status within observations and experiments. As Hans-Jörg Rheinberger has suggested, scientific prob- lems and experimental conditions or, in his terms, “epistemic things” and “technical objects”, are “engaged in a nontrivial interplay”: “The technical conditions determine the realm of possible representations of an epistemic thing; and sufficiently stabilized epistemic things turn into the technical repertoire of the experimental arrangement.” [Rheinberger 1997, 29]. Accordingly one may invert Gaston Bachelard’s often quoted dictum that „instruments are nothing but theories materialized“[Bache- lard 1934, 13], and say that materialities leave their mark on the in- terpretations of epistemic things. But Lenoir’s concept of experimental apparatuses and technical devices as material representations or models of physiological processes calls for further refinement. In his example the arrangement of apparatuses works as model in two ways: as a hypoth- esis of the inner ear’s functioning and as a schematic but on principle exact reproduction of the organ’s properties. In general, however, it seems that a certain apparatus must neither be actually present in an investigation in order to have an effect on the latter nor can the relation Telegraphy as Working Model of Nerve Physiology 131 between the model-apparatus and the modeled object be reduced to one singular possibility. This is in particular true for the several attempts to develop the nerve’s qualities with respect to the telegraph wire. As a closer look to the German speaking context between 1810 and 1860 will show, telegraphic installations attracted rather different problems of nerve-physiology at different times.1 Discussion The years around 1800 mark the beginning of a new epoch in the history of telecommunications. Had telegraphy previously been the toy of ama- teurs and outsiders, it came under the protection of the state at the turn of the Century, when large optical telegraph-lines were built and plans for electrical telegraphy were developed [Aschoff 1989, chap. 9-11]. These decades are also regarded as a time of a major change in the history of physiology. The Cartesian, mechanically determined “homme machine” made way for the new “homme sensible”, characterized by an excitabil- ity and sensitivity of a still unknown nature [Moravia 1978]. Both the development of telegraphy and the conceptualization of the human body as a sensorimotor organism touch on the same problem of information- transmission and -exchange. Practical questions are: by which force can a sign or a sequence of signs be transmitted over longer distances, what kind of principle guarantees that a sensation from the periphery of the body arrives without damage in the ‘sensorium commune’, what induces the voluntary movement of a muscle and in which way can information — a word or a sentence — be represented in signs. Around these problems manifold points of contact evolved between telegraphy and physiology in the course of the 19th Century but, as we will soon see, apparatus and organism did not form a stable, continuous relation It seems to be a conventional analogy, when, in the 1860’s, Helmholtz pictures the nervous system, the sensory organs and the muscle activity as a system of telegraphic wires, transmitters and receivers at length to- wards the end of his argument on the perception of the quality of tone. At least this impression is aroused in his first sentence: “Nerves have been often and not unsuitably compared to telegraph wires.” [Helmholtz 1870, 224]. It will become clear shortly, what “often” really means. Helmholtz himself may have had a popular lecture given in December 1850 in mind, were he drew this parallel for the first time [Helmholtz 1882-1895, II, 1For the widespread (not only physiological) contexts, in which after 1850 the human organism became related to communication devices, see [Otis 2001]. 132 Christoph Hoffmann 873]. Some weeks later and independently from Helmholtz the phys- iologist Emil du Bois-Reymond developed the same idea in a lecture on ‘animal locomotion’ [du Bois Reymond 1912, I, 47-48]. Despite this chronology, Helmholtz acknowledged his colleague’s original authorship: “With regard to the correspondences in our lectures, I leave the priority of the electric telegraphs to you because I heard the hypothesis that the ganglia represent the relays of electric telegraphs in the nerve-lines from you a long time ago.” [Kirsten 1986, 111] What apparently neither Helmholtz nor du Bois-Reymond remem- bered, was the simple fact that Johannes Müller — their mutual teacher at the University of Berlin — had already compared nerve fibers to “con- ducting wires covered with silk” (although not explicitly to telegraph wires) fifteen years earlier in his fundamental Handbuch der Physiologie des Menschen [Müller 1833-38, I, 684]. Müller himself refers to a publica- tion by the physicist Gustav Theodor Fechner and, as we will see, Fech- ner in turn silently picked up an idea of the famous anatomist Samuel Thomas Soemmerring. Without doubt one can easily assume more com- plete and above all other genealogies beyond the German speaking sci- entific community. But what matters here is that the history of the comparison between nerve and telegraph wire in itself shows such a for- getfulness that questions of priority and a perspective, which seeks for a constant relation, become futile. If, in the following, Soemmerring forms the starting point of my analysis, this is not because everything Helmholtz or du Bois-Reymond, for example, thought and wrote on the relationship between the physiology of the nerve and telegraphy origi- nates from here. It rather marks an early attempt to connect these areas, which was subsequently transformed and partly abandoned. In his treatise “Über einen elektrischen Telegraphen”, published in 1811, Samuel Thomas Soemmerring gave an account of the galvanic- electric telegraphic apparatus he had constructed in the years before on behalf of the Bavarian Academy of Science.2 As source of electricity for the transmitter he used a voltaic pile, to which 35 wires could be connected, each of them representing one of the 25 letters of the Ger- man alphabet and the numbers 0-9 (Fig. 1)3. The receiver consisted of a container filled with water where every single wire coming from the transmitter ended separately. In order to transmit a message, two of the wires were attached to the negative and the positive pole of the pile, thus closing the electric circuit. As a result, hydrogen respectively