Air temperature in Wrocław (Breslau) in the period 1710-1721 based on measurements made by David von Grebner

Abstract

The history of early-instrumental meteorological observations in Poland is quite rich and is among the longest in the world. The first observations were made in Warsaw in late 1654 or early 1655, while the temperature series described and analysed here is the second oldest instrumental series in Poland. Temperature and atmospheric pressure observations were made in Wrocław (Breslau, nowadays south-west Poland) from April 1710 to December 1721 by the physician David von Grebner and both series are now the longest surviving Polish series of their kind (Grebner 1723, for more details see also Przybylak 2010). David von Grebner used the Florentine thermometer (Thermometrum Academiae Florentinae), which had a brass scale with a star in the middle, above which were 80 degrees and below which were 100 degrees (Landsberg 1983). The results of his observations are available in unpublished form in the Library of Wrocław University. For purposes of comparison, another Wrocław physician – Johann Kanold (1679-1729) – began meteorological measurements in Silesia (e.g. Wrocław, Oława, and Legnica) and in other European countries in 1717. He recorded measurements in Wrocław up to 1726, and then from 1727 to 1730 they were continued by Andreas Elias Büchner (1701-1769), a professor of medicine at Wrocław University (Brázdil and Valášek 2002, Munzar 2003, Brázdil et al. 2008). These included measurements of air temperature, air pressure, wind direction and general descriptions of weather. Measurements were taken three times a day and the results were published in an encyclopaedic series Sammlung Von Natur- und Medicin-, Wie auch hierzu gehörigen Kunst- und Literatur-Geschichten (the so-called Breslauer Sammlung – Wrocław Collection). In the early-instrumental measurement period observers used thermometers with unknown individualised scales which are difficult to convert to the scales used in present-day instruments. That is why comparison of temperature changes between historical times and the present day is rather difficult. At the first half of 36 the 18th century all over Europe, thermometers based on the Florentine thermometer (Magnum Thermometrum Academiae Florentinae) have often been used. However, these instruments were different from those originally constructed in Italy. For example, in Europe (including Italy) Florentine thermometers with 180-degree, 200-degree or even with 360-degree scales were used (Middleton 1966, Quinn and Compton 1975). Moreover, the two fixed points used in the construction of today’s thermometers (freezing and boiling points) were not used in these thermometers. That is why, even comparison of temperature measurements made by different thermometers of the same type can be impossible, if the instruments were not identical and more research is still needed to solve the problem of converting the old scales to new ones. Some work has already been done on this issue (e.g. Camuffo 2002a, 2002b, Cocheo and Camuffo 2002), however, similar investigations are needed for other copies of thermometers. At present the only way we can compare the historical and present climate is by using the index method for available temperature measurements (for more details about this method see, e.g. Pfister 1992 or Przybylak et al. 2005). For the purposes of describing the present temperature characteristics in Wrocław the following studies have been used: Kosiba (1948), Pyka (1991, 1998), Dubicka (1996), Dubicka and Pyka (2001).