At the beginning of the 19th century, when the construction of the Tartu Observatory was completed, meteorology had not yet developed into an independent branch of science. Medical people, physicists and astronomers were dealing with weather observations.

Since 1783 it was one of the tasks of the province doctors in Estonia and Livonia to carry out weather observations but no data about it has survived concerning Tartu. In 1806–1809 the newspaper Dörptsche Zeitung published regular data of weather observation but it is not known who and with which equipment carried them out. It is supposed that it was professor of physics G. F. Parrot. In the archives of the observatory there is a diary of weather observations which belonged to mathematics and astronomy professor Pfaff with his observations in Gronau in 1808. It is possible that he also dealt with this field in Tartu. As weather observations belonged both to the discourse of physics and medicine, the student of medicine K. E. v. Baer dealt with it during writing his Doctoral thesis in 1811-1813. The oldest preserved diary of meteorological observations in the observatory’s archives belongs to 1826-1828.

The diary of weather observations, 1827 (TO).

The newspaper Inland published weather information regularly since 1839. In the Tartu Observatory regular meteorological observations were started by professor Mädler who became the observatory’s director in 1841. Usually he made these observations himself but when he was not in Tartu, some astronomer present made them. In 1850 the assistant director Carl Lais was appointed with the special task to organize weather observations. The results were regularly published in the Inland newspaper. Three times a day (at 9 in the morning, at 2 by day and at 9 in the evening) air pressure and temperature observations were made, maximum and minimum temperature was measured, the velocity and the direction of wind and cloudiness were registered. The data of the period from 11.09.1840 to 31.12.1844 have been preserved but from 18 June to 31 October 1844 the morning temperature was not measured. They had calculated the mean values for the air pressure and temperature for each ten days, the month and the quarter of the year, also the wind roses have been drawn for each year.

Professor Mädler’s overview of temperature changes in 1825-28, winter and spring (TO).

At the same time (1842–1853) with Mädler meteorological measurements in Tartu were carried out by the professor of physics Ludvig Kämtz (1801–1867) in his house at the River Emajõgi which gives valuable data for comparison. Mädler considered meteorology very important and believed that the possibility to exchange data quickly with the help of the telegraph service will make forecasting based on scientific research.

Twenty years later Mädler’s measurements did not satisfy the requirements of the professor of physics Artur Joachim von Oettingen (1836–1920) any longer (there was no exact overview of the equipment used in measuring, their location and calibration), but he still used Mädler’s data of the mean temperature in 1840–1844 for the comparison of his own measured monthly mean temperatures for the year 1867.

In 1865 A. v. Oettingen established a separately located meteorological observatory (at first in his own house but later in the main building, then in the students’ hostel which after World War 1 was converted into the Central Archives of the Republic of Estonia). Later weather observations did not belong to the tasks of the Tartu Observatory. The last preserved observation diaries of 1871 can be found among the materials of the Tartu Observatory. The Chair of Physical Geography and Meteorology was established at Tartu University in 1874.

On the right: The barometer made by the university mechanic Brücker, 1830-1840s (TÜAM, photo V. Valder).