Spektrometr Zantedeschiego-Porra – najstarszy zachowany dwuramienny przyrząd do obserwacji widma liniowego

Until today, in the world collections of historic scientific devices only three complete spectroscopic apparatuses have survived. They were used for line spectrum observation and they date from before 1860, i.e. before Bunsen’s and Kirchhoff’s spectrochemical analysis was aknowledged. The subject of this article concerns inventory item No 348/10383 kept in the Museum of the History of Physics at the Padua University. With probability that equals certainty, the item was identified as spectrometer (spettrometro), constructed in the years 1852-1855 by Porr for Zantedeschi and his physical office at the Padua University. The identification was made on the basis of the following sources: little-known scientific articles of this Italian physicist, Francesco Zantedeschi (1797-1873), unpublished letters of Italian optics specialist and topographer, Ignazio Porro (1801-1875), illustrations of scientific devices, and descriptions from museum catalogues. In the perspective of the early history of optical spectrum apparatuses, Zantedeschi-Porro spectrometer should be considered as the oldest known and preserved two-armed (not with double telescope!) device to observe the line spectrum.