The Legend of the Świeradów Frog and Radon Mineral Water
While out walking during a stay at Świeradów-Zdrój, formerly Bad Flinsberg, the Berlin physician Leonard Thurneyssen observed a lifeless frog lying in one of the springs. Although at first this aroused no greater interest in the physician, in the course of a later walk in the vicinity of the spring he found to his surprise that the frog was not decomposing. Intrigued by the fact, he wrote a brief note in his work of 1572, in the 10th book and 20th chapter, on the mineral waters of Świeradów, pointing out their medicinal properties:
“We have spoken previously, in the seventh book, in the 44th chapter, of medicinal springs, the properties of which are alike to the content and interaction of those which spill in the valley of the Kwisa river by the Czech border ... not far from Mirsk and Kamienica (Stara Kamienica)”.
It was only in 1739, however, that a medical committee was appointed, on the instructions of count von Schaffgotsch, consisting of medical specialists from Mirsk and Lwówek Śląski and a physicist from Gryfów Śląski, to conduct a thorough examination of the chemical composition of the waters, recognizing them as a result to be medicinal. The discovery confirmed that radon mineral water springs were present in Świeradów-Zdrój. The frog in turn has been immortalized.
Today the frog is treated as one of the symbols of the town and is used for its promotion.