Tobias Mayer

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Tobias Mayer
(engraving by Conrad Westermayr )

Tobias Mayer (also Majer ; born February 17, 1723 in Marbach am Neckar , † February 20, 1762 in Göttingen ) was a German astronomer , geographer , cartographer , mathematician and physicist . Although he had never studied at a university as an autodidact , he was a recognized scientist of his time.

life and work

Göttingen memorial plaque for Tobias Mayer

Mayer was born in Marbach am Neckar and grew up in poor conditions in Esslingen am Neckar . After the death of his father in 1731, he received accommodation in the orphanage . From 1729 to 1741 he attended the German school and the Latin school in Esslingen. Since mathematics was not offered in the Latin school, Mayer continued his self-didactic training in this discipline. Due to his great talent, he was temporarily promoted by the mayor of Esslingen. His mother died in 1737.

In 1739 he published the first city map of Esslingen, in 1741 a book on geometry and mathematics, in 1745 the "Mathematical Atlas" and a book on war architecture. When he took up a job at JB Homann's cartographic institute in Nuremberg in 1746 , he had already published two original works in geometry . Mayer uncovered the inaccuracies of the maps used at the time by drawing two common maps on top of each other and finding large differences, especially in an east-west direction. The determination of the longitude of a town at that time was only possible with great uncertainty.

In 1751 he married Maria Victoria, b. Gnügen (1723–1780), and in the following year his son Johann Tobias was born, who later also became a physicist. (In some texts the father is mistakenly referred to as Johann Tobias Mayer . According to the baptismal register and original publications, his first name is simply Tobias .)

Göttingen, Tobias-Mayer-Weg

Because of his improvements in the field of cartography and because of his reputation as a scientist, he was appointed to the Chair of Economics and Mathematics at the University of Göttingen in 1751 . In 1751 he was elected an extraordinary member and in 1753 a full member of the Göttingen Academy of Sciences . 1752–1756 he completed publications on length determination , astronomy, geophysics, mathematics and measuring instruments. In the years 1757–1762, despite the Seven Years' War, he published further works on astronomy, but also on the earth's magnetic field and color theory .

In 1754 he became head of the newly established observatory , which was housed in a tower of the Göttingen city ​​wall . He worked there with great enthusiasm and success until he died of typhus in 1762.

Scientific achievements

astronomy

His first important astronomical work was a careful study of the libration of the moon ( Kosmographische Nachrichten , Nürnberg 1750). His moon map , published posthumously by Lichtenberg in 1775 , was unsurpassed for half a century. Mayer's fame is mainly based on his moon tables , which first appeared in print in 1752. In 1755 he submitted an expanded version of these tables to the British government. They were so precise that the position of the moon could be determined to within 5 arc seconds and thus the geographic longitude at sea to within 0.5 °.

Thus a solution to the so-called length problem was found, which up until that time had prevented safe navigation on the high seas. The English watchmaker John Harrison developed another solution for the same problem around the same time : it was based on time measurement using newly developed clocks that were sufficiently accurate even under the rough conditions on board a sailing ship on the high seas.

Mayer's scientific theory, on which the lunar tables were based, was only published posthumously under the title Theoria lunae juxta systema Newtonianum in 1767 in London. His improved version of these tables also appeared posthumously in London in 1770. Mayer's widow sent these tables to England via the University of Göttingen. In recognition of Mayer's contribution to solving the length problem, she received a £ 3,000 bonus from the British government. As early as 1714, the British Parliament had offered a price of 20,000 pounds for the length problem and set up a committee, the Board of Longitude , for it.

Mayer's moon maps were later taken up by Johann Hieronymus Schroeter , among others .

The moon crater T. Mayer was named after him.

Invention of the repeater circle

In the middle of the 18th century there were slight deviations between the predictions of Newton's theory of gravity and the actually observed planetary words . These differences were up to 5 arc minutes for the moon, for example , which could result in an uncertainty of 2.5 degrees when determining the longitude on earth. Depending on the latitude , this meant a deviation or navigation inaccuracy of up to 150 nautical miles . Due to the need for more precise observations to create a better theory of motion of the moon, Tobias Mayer constructed a new astronomical measuring instrument, the so-called repetition circle . The device was initially used in land surveying and consisted of two mutually rotatable and separately lockable sighting devices with telescopes .

To measure, you aim at the angle between two terrestrial points, one of which is a reference point . This process is repeated several times. After, for example, three bearing processes, the circular disk shows three times the angle you are looking for. The advantage of this method is that the inevitably occurring measurement error is smaller than when the circle is set and read once . Mayer's invention itself did not bring any fundamental innovation, but his repetition principle reduced the angle errors in practical measurements. Repeated angle measurements brought previously unattainable levels of accuracy to land surveying.

Mayer transferred this repetition principle to an astronomical mirror circle . The angular difference between the moon and star is determined by repeated measurements and then dividing by the number of sights. From 1755 onwards, Mayer succeeded in setting up his moon tables with an accuracy of about one arc minute. The astronomer Franz Xaver von Zach (1754-1832) later described the Mayer mirror circle as the greatest astronomical invention of the 18th century.

The first models of the new device were made in Göttingen from 1750 and by John Bird in London from around 1757 . Mayer soon realized that the refinement that he could achieve for his lunar theory with the help of such an instrument was also suitable for a reliable method of determining length at sea. However, it was not until three years after Mayer's death that measurements by the English “Board of Longitude” showed that the accuracy of the location at sea could be improved to around 60 nautical miles using Mayer's method. From 1785 these devices became known as Borda circles and were widely used.

Mayer's solution to the longitude problem

Two moon observations at the same true local time. The east-west distance between the two observers is 90 degrees of longitude, which corresponds to a difference of 6 hours universal time.

The figure on the right illustrates the solution principle for the longitude problem , which was first discussed by Johannes Werner in his Nova translatio primi libri geographiae Cl. Ptolomaei (Nuremberg 1514) was mentioned. Based on Newton's theory and more precise astronomical observations, Mayer has decisively improved the tables required for calculating the moon positions.

If the moon is observed simultaneously (i.e. at the same world time ) at different locations on earth, its position in the fixed star sky differs by up to 2 °. This parallactic shift gives a way to determine the difference in length between the two locations. Instead of the second location, however, a reference point (e.g. Greenwich) is now used , for which the hourly moon position has been calculated in advance in a moon table. The observer can calculate the current world time from the moon movement.

As a second variable, it determines the true local time of its location by measuring the position of the sun . The difference between local and world time corresponds to the longitude of the observer. Since the moon moves on its orbit around the earth at about 33 angular minutes towards the east against the fixed star sky, the deviation of the true local time from the world time and thus your own can be determined by measuring the angular distance between the moon and neighboring bright fixed stars Determine longitude. With his moon tables, Mayer provided the most precise data on the movement of the moon in the fixed star sky.

museum

Tobias Mayer's birthplace in Marbach am Neckar

Tobias Mayer's birthplace has housed the Tobias Mayer Museum since 1996. It is not far from the house where Friedrich Schiller was born at Torgasse 13 in Marbach am Neckar . The museum was and is set up and maintained by the Tobias Mayer Association .

Works

  • Firstfruits: along with some news about his inventions and his life . Schreiner, Düsseldorf 1812 digitized

literature

  • Peter Aufgebauer : The beginnings of astronomy in Göttingen. In: Göttinger Jahrbuch Volume 50 (2002) pp. 75–92
  • Bernd Feicke:  Mayer (Majer), Tobias. In: Biographisch-Bibliographisches Kirchenlexikon (BBKL). Volume 33, Bautz, Nordhausen 2012, ISBN 978-3-88309-690-2 , Sp. 811-815.
  • Menso Folkerts :  Mayer, Tobias. In: New German Biography (NDB). Volume 16, Duncker & Humblot, Berlin 1990, ISBN 3-428-00197-4 , pp. 528-530 ( digitized version ).
  • Eric G. Forbes: Tobias Mayer (1723-62). Pioneer of enlighted science in Germany. Göttingen 1980. ( Works from the Göttingen State and University Library, Volume 17)
  • Siegmund Günther :  Mayer, Johann Tobias . In: Allgemeine Deutsche Biographie (ADB). Volume 21, Duncker & Humblot, Leipzig 1885, pp. 109-116.
  • Armin Hüttermann: Tobias Mayer and Nürnberg - From mathematics to cartography to astronomy in: Regiomontanusbote , magazine of the Nürnberger Astronomische Arbeitsgemeinschaft eV, 25th year 3/3012, pages 14-19.
  • Armin Hüttermann (Ed.): Tobias Mayer, 1723 - 1762. Mathematician, cartographer and astronomer of the Enlightenment period , Tobias Mayer Museum, Marbach am Neckar 2012 (series of the Tobias Mayer Museum eV Volume 35), ISBN 978-3- 88282-074-4 .
  • Peter H. Meurer : Background and analysis of Tobias Mayer's «Critical Map of Germany». In: Cartographica Helvetica Heft 12 (1995) pp. 19–26 full text
  • Erwin Roth et al. a .: Tobias Mayer. Positioning pioneer. Pioneer of modern navigation systems. Marbach 1995
  • Steven Wepster: Between theory and observation. Tobias Mayer's explorations of lunar motion 1751–1755 , Springer Verlag, 2010, Sources and studies in the history of mathematics and the physical sciences
  • Tobias Mayer 1723 - 1762, surveyor of the sea, the earth and the sky, Esslingen in old and new maps: Exhibition d. Esslingen City Archives, November 1985 to January 12, 1986 in the Salemer Pflegehof / erarb. from the Tobias Mayer Museum Association Marbach a. N. u. from the state survey office of Baden-Württemberg. Esslingen 1985.

Web links

Commons : Tobias Mayer  - Collection of images, videos and audio files

Individual evidence

  1. ↑ In its article, the ADB gives the full name with Johann Tobias Mayer , who is also noted as an alternative name in the information provided by the DNB.
  2. ↑ Holger Krahnke: The members of the Academy of Sciences in Göttingen 1751-2001 (= Treatises of the Academy of Sciences in Göttingen, Philological-Historical Class. Volume 3, Vol. 246 = Treatises of the Academy of Sciences in Göttingen, Mathematical-Physical Class. Episode 3, vol. 50). Vandenhoeck & Ruprecht, Göttingen 2001, ISBN 3-525-82516-1 , p. 163.
  3. ↑ Pages 115–16, Allgemeine Deutsche Biographie (ADB), Volume 21 (Leipzig 1885).
personal data
SURNAME Mayer, Tobias
ALTERNATIVE NAMES Majer, Tobias; Mayer, Johann Tobias (full name)
BRIEF DESCRIPTION German cartographer, geographer, mathematician, physicist and astronomer
DATE OF BIRTH February 17, 1723
PLACE OF BIRTH Marbach am Neckar
DATE OF DEATH February 20, 1762
Place of death Goettingen