Johann Tobias Mayer

Johann Tobias Mayer , 1723-62, German mathematician and astronomer. In 1751 he became professor of economics and mathematics at the Univ. of Göttingen, and in 1754 director of the observatory there. He is especially noted for his lunar tables (1752), which were important in precisely determining longitude at sea. Mayer is remembered also for his improvements in mapmaking and for the invention of the repeating circle, later used in measuring the arc of the meridian. A collection of his memoirs was published in 1775; a revision of his catalog of 998 zodiacal stars, newly computed, appeared in 1894.

Gregory, Johann Gottfried (1631–75), German pastor, who in 1658 was appointed to the Lutheran Church in Moscow where 10 years later he founded a school. In 1672 he was responsible for the first organized dramatic entertainment given before the Russian Court on the orders of Alexei, father of Peter the Great. This was The Play of Artaxerxes, taken from the repertory of the English Comedians and performed in German by German students in Moscow. It lasted 10 hours, and was enlivened by songs, music, dancing, and comic interludes. Gregory later produced The Comedy of Young Tobias (1673) and, with Russian student-actors whom he had trained himself, The Comedy of Holofernes (1674). He is portrayed in A Comedian of the Seventeenth Century by Ostrovsky. His theatre, a hastily erected wooden building in the summer palace at Preobrazhen, survived until Alexei's death in 1676, when it was pulled down.

Euler, Leonhard (1707–83)Swissmathematician. He refined the mathematical theory of the Moon's motion, and calculated improved orbits for Jupiter and Saturn. His lunar theory helped the German cartographer and astronomer Johan Tobias Mayer (1723–62) to produce highly accurate lunar tables; its full merits would come to be appreciated by G. W.Hill, over a century later. Euler's work on optical systems strongly influenced the technical development of telescopes. He also worked on planetary perturbations, the orbits of comets, and the tides.