The foundation of the Collection of Old Scientific Instruments of the Laboratory for Experimental Psychology was, among other things, an attempt to preserve a part of the history of our science. This attempt disclosed some strange events, examples of collective amnesia and negligence, but also vague outlines of extraordinary personalities. At the very start of our enterprise we were challenged to unravel the origin and purpose of the instruments of which we knew almost nothing. We stood before the devices that with time had slid into oblivion, but, owing to a strange concurrence of events, had managed somehow to span almost a century. It was as if we found ourselves before the vestiges of a civilization which had left objects of outstanding beauty behind, but with neither remembrance nor a written trace of the men who had created it.

The foundation of the Collection was also an opportunity for an entirely novel understanding of our precious heritage, the importance of which still eluded us. For decades the Department of Psychology at the University of Belgrade was in possession of the instruments which now constitute the Collection. They were believed to have been part of German war reparations to the Kingdom of Yugoslavia after World War One, but there was no evidence whatsoever as to how they had got there, whether they had been ordered and, if so, who might have ordered them. For years they were stored in cupboards, in the office of Professor Baja Bajić in Takovska Street, Belgrade, the seat of the Department of Psychology since 1957. Seventy instruments, forty of which were made by the craftsman Zimmermann from Wundt’s Leipzig laboratory, sank in oblivion, their glow fading away under the dust that covered them.

Although the origin of the instruments now belonging to the Collection has mostly remained obscure up to now, the unveiled part of their history had its dramatic moments. After Prof. Bajić retired in the early sixties, most of them were written off the inventory. A professor (teaching assistant at the time) suggested that they should be sent to a junk yard, and that for the money thus obtained a tape recorder should be bought for the assistants to listen to the music. Fortunately enough, the idea was not realized. The credit for their preservation goes to Professor Predrag Ognjenović. When in 1974 the Department of Psychology moved from Takovska Street into the new building of Faculty of Philosophy, he carefully collected the instruments and relocated them to the newly established Laboratory of Experimental Psychology. The instruments were thus preserved. They were given the place they deserve in 1982 when the Collection was founded. Their significance was officially acknowledged in 1992 when the Collection became part of the Association of Museums of Science and Technology of Serbia. The instruments were thereby granted the status of a state-protected cultural asset.

At the time the Collection was constituted, the instruments were in poor condition. Many were affected with rust because they had never been cleaned, and most of them had one or two parts missing. We could not fully grasp the purpose of some instruments, while some were so curious we could not even guess what they were intended for. With the generous help of Prof. Ognjenović I made every effort to identify the instruments, reconstruct them, and, if possible, restore them to their original condition. Sometimes I was successful, but occasionally I did not even come close to determining their original appearance.

And then the first lead appeared. In the legacy of Professor Borislav Stevanović donated to the Library of Department of Psychology I found the catalogues of Zimmermann and Diel, who were among the leading European manufacturers of scientific equipment at the beginning of this century. Zimmermann’s catalogue was mailed to Prof. Stevanović, with the name of the addressee neatly written on it. It is likely to have arrived in Belgrade in 1930, since the information about the change in prices for that year was enclosed with it. The calalogue alone, however, was not proof that Prof. Stevanović had indeed ordered the instruments. This discovery led Dejan Todorović and myself to make another attempt at identifying and reconstructing the old devices. The catalogue contained their technical descriptions and engravings, which helped us not only to find out the names and purpose of most of them, but also which parts were missing. This was an invaluable source of information.

Nevertheless, a number of instruments could not be reconstructed. Either they were not listed in the catalogue, or were not manufactured by Zimmermann. Furthermore, it was not clear whether some of them had disappeared, or had been damaged beyond the possibility of repair. A search through the old inventory books of the Faculty of Philosophy seemed to be the easiest way to find it out and get an insight not only into the names of the instruments, but also into their origin. It turned out, however, that the Faculty had no records of the kind going back further than twenty years. We appeared to have come full circle. There was reason to believe that the way and date by which the instruments had reached the Faculty of Philosophy would never be revealed. The only way left led us to the Archive of Serbia, where we hoped the old inventory books might have been relocated, but they were not there either. In the hope that the instruments might have been part of the war reparations after all, and that some trace of them should exist in the Archive, we turned our attention to the relevant documents.

It turned out that by the end of 1927 the Faculty of Philosophy had proposed a list of expenses to be covered from the war reparations funds. A reference was made there to some psychological instruments valued at 5082 Reichsmarks in gold. The plan was not endorsed by the Ministry, as could be seen from the complaint the Faculty lodged a year later. That some of the instruments had arrived was indicated by an acknowledgment issued in 1930 of "the receipt of psychological devices in accordance with the reparations agreement", but the acknowledgment gave no specifications of those devices.

The crucial moment in our search through the Archive was the discovery of a letter Prof. Stevanović sent to Veselin Čajkanović, Dean of the Faculty of Philosophy, requesting the acquisition of psychological instruments valued at 4994 Reichsmarks. In this letter, dated January 1st, 1931, mention was also made of a psychological laboratory. Enclosed with the letter was the list of instruments, their prices and catalogue numbers cited after Zimmermann’s catalogue. With the discovery of the letter we obtained an unchallengeable evidence as to who had ordered the instruments. Thus they did not get there anonymously, as part of war reparations, but were purchased with the intention of establishing a psychological laboratory.

An inspection of Prof. Stevanović’s order showed that half the instruments listed were not in the Collection. Had they arrived and been destroyed then?¹ Only half the items in the Collection were purchased from Zimmermann, whereas another half were the products of other manufacturers (Boulitte, Palmer, Diel, and Marx & Berndt). This suggests that Prof. Stevanović came into possession of only a part of the equipment he had requested in 1931, while the rest were obtained in the 30's. Whether these were acquired at the expense of the war reparations funds, or in some other way, cannot be inferred with certainty at present.

The process of reconstructing the origin of the instruments yielded the following: in 1926 Prof. Stevanović receives his PhD in experimental psychology from King’s College, London, a dissertation on cognitive processes in judgment. In 1927 a Department of Psychology was founded at the Faculty of Philosophy in Belgrade, and in 1928 Prof. Stevanović took the chair of assistant professor. The same year he was appointed director of the newly formed Seminar for Experimental Psychology. As the University of Belgrade was then granted books and equipment from the war reparations funds, Prof. Stevanović made a request to the Dean of Faculty of Philosophy in order to procure the means for the purchase of equipment. In order to make his request specific, he first ordered the scientific equipment catalogues from Germany. In all probability, a small number of instruments had already been acquired. In his request, for example, Prof. Stevanović asked for some accessories to a color-mixer, but not the color-mixer itself. One may thus presume that some earlier requests, probably between 1927 and 1930, had been granted in part. There is reason to believe that the request of 1931 was not fully granted either, because the Collection does not now contain all the items listed, while some of the instruments, as we have seen, were purchased from other manufacturers.

The list of requested items permits a conclusion that Prof. Stevanović intended to establish a laboratory which would deal with various aspects of experimental psychology. He did not aim to create a specialized laboratory for the study of, say, memory or perception. The equipment may be sorted into devices for the study of visual and auditory perception, of memory and learning, into kymographic and ergographic recording devices, and those for the study of emotions. Neither from Prof. Stevanović’s published papers, however, nor from the memory of his students can one infer that he really conducted experiments which would require the equipment he ordered. It is certain, though, that part of it was used in student tutorials. There is no doubt that in demonstrating certain psychological phenomena to the students Prof. Baja Bajić was using Ranschburg’s mnemometer, the color-mixer, the esthesiometer and the perimeter. Some instruments served this purpose up to 1982, the year the Collection was founded. And although their application in student tutorials is unquestionable, it is their choice that remains a puzzle. Thus, for example, there are four color-mixers in the Collections although only one would suffice for demonstration purposes. On the other hand, many instruments could not have been used in demonstrations, because they require special conditions and technical skill. Doubts thus arise that the origin of some instruments and the motives for their acquisition have not been entirely unveiled.

The reconstruction was no less exciting than the quest for their origin. That task demanded technical knowledge we did have to some extent, but also persistence and imagination we had in abundance. A little black box, for example, was a complete riddle. It had an opening with two finely done steel plates, one of which could move from side to side, this motion being readable by means of a micrometer. The device whose name or purpose we did not know was Zimmermann’s product, but it was not listed in the catalogue. In Prof. Ognjenović’s opinion, it was used in the study of tactile sensitivity, but we failed to understand its working principle. In the inventory books of the Faculty of Philosophy, an entry was made of an item designated as "inhonometer", a word completely unknown to us. The prefix "in" implied its Latin origin, but the base "honor" made no sense. After a while, we found out that the moving plate could also move up and down slightly. By passing the finger over the plates, a difference in their respective levels could be detected. We thus decided that the instrument’s purpose was that of determining absolute and differential thresholds of tactile sensitivity. After consulting a Latin dictionary we concluded that its name could not be "inhonometer", but that, most probably, it was derived from the Latin verb "inhorresco", i.e. "to undulate", "to vibrate". As the plate could move up and down, "undulating finely", the instrument’s name, we decided, must have been "inhorometer". However, this conclusion may require further evidence. In the catalogue we did not therefore use that name for the instrument, but we left a neutral term - "apparatus for testing tactile sensitivity".

We experienced a similar thrill when reconstructing Boulitte’s device for light stimuli. For years we stood helpless before a wooden box with an opening through which we could see three glass tubes. One contained a residue of mercury, and in the other two traces of a yellow powder could be discerned. The mystery was enhanced by a tag reading "Uran - vert" on one tube. Prof. Krmpotić and Prof. Aničin from the Faculty of Physics in Belgrade, identified them as Geissler tubes, which helped us understand their function. Such tubes contain gas. When electrified, they take on a luminous glow, the color which depends on the gas. At the box top were three outlets marked with the letters R, V, and B respectively. The device being of French origin, we inferred that the letters stood for "rouge", "bleu" and "vert", meaning the instrument glowed on red, blue and green colors. It had never occurred to us to make any connection between this device and three electric bells of different sizes, which also rested in a showcase of the Collection. The identical type of electric connections on these two devices helped us conclude that they were Boulitte's product as well. Quite apart from the bells and Geissler tubes, there stood a complex switchboard, also a Boulitte’s product. On this switchboard, the word "lumière" (light) was written next to three outlets, and the word "sonnerie" (ringing) next to the correspondingly grouped outlets on the opposite side. There were therefore three bells, three light sources and a switchboard with three outlets for auditory and visual stimuli. We assumed that with this set the experimenter was free to activate only one auditory or light stimulus out of three, or to present them simultaneously. We inferred that the instruments of unknown purpose which we held to be mutually independent probably constituted a whole. This was not the only such discovery we made during the reconstruction.

From the documents we found we now know that the instruments were obtained in the course of the 1930's, but the question still remains as to when they were manufactured. We also know they resulted from the joint efforts of a scientist and a craftsman - the former formulating a problem and designing an instrument to study it with, and the latter building it. Thus, for example, in the paper describing his Leipzig laboratory Wundt mentions Mr. E. Zimmermann, a craftsman who manufactured instruments for the laboratory (Wundt, 1910). These notes give evidence that the craftsman Zimmermann has made a member of the lab team, had his workshop at the Institute, and that the experiments would have been unimaginable without his contribution. Nowadays things have changed, but there still is an admiration and a touch of nostalgia for the times when scientific instruments were made by hand, not just to serve a purpose, but also to be beautiful. Besides being the master of his skill, each of those craftsmen was also an artist expressing the spirit of his epoch.

The only reliable indication so far of when the instruments were manufactured is a kymographic test record enclosed as a certificate with Zimmermann’s electromagnetic tuning fork for direct time recording. Besides the instrument’s catalogue number, it indicates that the testing was carried out on 29th November, 1926. The primary role of such forks being the setting of a fine time base for kymographic recording, the manufacturer considered it necessary to provide a proof attesting that the product was in order and properly tuned. The sender’s label (Zimmermann, Leipzig) is still attached to the fork, indicating Belgrade as its destination, but with no addressee. Nevertheless, that the design of most of the instruments could be dated to the turn of the century is suggested by the descriptions and the occasional engravings we find in psychological journals and books from those times. Although our copy of Zimmermann’s catalogue dates from the end of the 1920s, the appearance of the instruments remained the same, with minor technical modifications not affecting the basic working principles.

At present the Collection includes some sixty instruments covering various fields of experimental psychology. Along with books and journals in the Library of Department of Psychology, dating from the end of the last and the beginning of this century, the instruments constitute a whole which allows the reconstruction of a psychological laboratory as it was at the turn of the century. An understanding of the working principles of the instruments, their constructional solutions and building techniques bring us closer to the spirit of an epoch, providing a testimony to the very beginnings of psychology as an empirical science and to its standards. Through these instruments we may intuit the scientists' way of thinking at the turn of the century, hear them ask questions and solve a problem. If we listen carefully, we may hear them ever telling the same story about the adventure of searching and the thrill of discovery.

The instruments now stand in front of us, beautiful and silent. It is as if we had had a dream but could not remember it the moment we woke up. We are left with the objects from our dream reminding us how beautiful the dream may have been.

This text is an excerpt from:

Kostić. A. &Todorović. D. (1997). Sense, Mind and Measure. Belgrade. Margo-Art and Dosije.

¹ That some instruments might have been destroyed during German retreat from Belgrade in 1944 is indicated in the testimony of Živorad Vasić, published in '100 years of the Faculty of Philosophy' (Narodna knjiga, Beograd, 1963, p. 210).