Recent studies of scholarly data work argue that whatever researchers handle as data and, in particular, what researchers consider as potential evidence for supporting claims, counts as data. In this article I extend the relational approach towards data to the various ways of dealing with data in the course of a single research project. Relying on an example from ecology, I argue that data gain presence for and occupy researchers in manifold ways: for example, as a promise, desire or pressure, or as a problem of trust and strength. In this way we notice that data, in the eyes of researchers, have more than one mode of existence, each of which is linked with its own expectations, challenges and actions. And we notice that these modes of existence not only coexist in the framework of a single project, but can also compete with each other.

The contributions to this volume originate from the workshop “Hauptsachen und Nebendinge—Pure Science and its Impurities”, organized by Christoph Hoffmann, which took place at the Max-Planck-Institute for the History of Science (Berlin) in July 2000. We wish to thank all participants for rich and stimulating talks and discussions.

During the “institutional revolution” between 1870 and 1910 almost two dozen physics institutes were newly erected in Germany. The design of these buildings was largely determined by sets of precautions against various sorts of disturbances. These undertakings were by no means unique. Recent historical studies have identified similar attempts in physics institutes outside Germany. But as yet, hardly a word has been wasted on the necessity of these precautionary measures. It seems to be self-explanatory that disturbances should be precluded from scientific investigations. My paper criticizes this approach. The evidential nature of this assertion rests on the questionable assumption that disturbances are “external factors”, which hinder physical research. I examine the ‘architecture of disturbance’ and show that it is the set of precautions itself which sometimes produces ‘disturbing’ effects. I then focus on particular sources of disturbance that were taken into account in the design of the buildings, and analyze the aporias that characterize the ‘external’ definition of disturbances. In conclusion, an alternative understanding of disturbances is offered. Following Michel Serres's concept of the parasite, I suggest that disturbances indicate the “being of relation” in physics research around 1900. From this point of view I finally sketch two novel features that governed the design of physics institutes after the turn of the century.