Born in the small village of Zagorica, near Dolsko eastern of Ljubljana, Slovenia, Jurij was 6 years old when his father Jernej Veha died. Jurij (German = Georg, English George) was educated first in Moravče and later in 1767 he attended high school for six years in Ljubljana. (subjects: Latin, Greek, religion, German, history, geography, science, mathematics). At that time there were about 500 students there. He was a schoolfellow of Anton Tomaž Linhart[?], a Slovene writer and historian. Jurij completed high school when he was 19, in 1773. After completing Lyceum[?] in Ljubljana he became a navigational engineer. Tentamen philosophicum, a list of questions for his comprehensive examination was preserved and is available in the Mathematical Library in Ljubljana. The problems cover the following areas: logic, algebra, metaphysics, geometry, trigonometry, geodesy, stereometry, geometry of curves, ballistic[?] and general and special physics.
Jurij left Ljubljana five years after graduation and entered military service in 1780 as Professor of Mathematics at the Artillery School in Vienna. At that time he started to sign his last name as Vega and no longer Veha. When Jurij was 33 he married Josefa Svoboda (Jožefa Swoboda) (17711800), a Bohemian noble from Budewice[?] who was 16 at that time.
In September 1802 Jurij Vega was reported missing. After a few days' search his body was found. The police report concluded that it was an accident. However, the true cause of his death remains a mystery, but it is believed that he died on September 26, 1802 in Nussdorf[?] upon Danube near Vienna, Austria.
Vega participated in several wars. In 1788 he served under Austrian Imperial FieldMarshal Gideon Ernst Laudon[?] (17171790) in a campaign against the Turks at Belgrade. His command of several mortar batteries contributed considerably to the fall of the Belgrade fortress. Between 1793 and 1797 he fought French Revolutionaries under the command of Austrian General DagobertSigismond de Wurmser[?] (17241797) with the European coalition on the Austrian side. He fought at Fort Luis[?], Mannheim, Mainz, Wiesbaden, Kehl[?] and Dietz[?]. In 1795 he had two 13.6 kg (30pound) mortars cast, with conically drilled bases and a greater charge, for a firing range up to 2998 m (3280 yards). The old 27.2 kg (60lb) mortars had a range of only 1791 m (1960 yd).
Vega published a series of books of logarithm tables. The first one appeared in 1783. Much later, in 1797 it was followed by a second volume that contained a collection of integrals and other useful formulae. His Handbook which was originally published in 1793 was later translated into several languages and appeared in over 100 issues. His major work was Zakladnica vseh logaritmov (Thesaurus Logarithmorum Completus[?] (Treasury of all Logarithms)) that was first published 1794 in Leipzig. An engineer Franc Allmer, honourable senator of the Technical university of Graz, has found Vega's logarithmic tables with 10 decimal places in the Museum of Carl Friedrich Gauss in Göttingen. Gauss used this work frequently and he has written in it his several calculations. Gauss has also found some Vega's errors in the calculations in the range of numbers, greater than a million.
Over the years Vega wrote a four volume textbook Vorlesungen über die Mathematik (Lectures about Mathematics). Volume I appeared in 1782 when he was 28 years old, Volume II in 1784, Volume III in 1788 and Volume IV in 1800. His texbooks also contain interesting tables. For instance one can find in Volume II closed form expressions for sines of multiples of 3 degrees. They are written in a form that is easy to work with.
Vega wrote at least six scientific papers. On August 20, 1789 Vega achieved a world record when he calculated pi to 140 (137 correct) places. This calculation he proposed to the Russian Academy of Sciences in Saint Petersburg (Санкт Петербург) in the booklet V. razprava (The fifth discussion), where he had found with his calculating method an error on the 113th place from the estimation of Thomas Fantet de Lagny (Lagney) (16601734) from 1719 of 127 places. Vega retained his record 35 years until 1824 and his method is mentioned still today. His article was not published by the Academy until six years later in 1795. Vega had improved John Machin[?]'s formula from the 1706:
with his formula, which is equal to Euler's formula from 1755:
and which converges faster than Machin's formula. He had checked his result with the similar formula:
He had developed the second term in the series only once. Japanese mathematicians of that time had used two approximations :
and
which were found in the same manner as John Wallis' method from the 1655 with the development in the infinite continued fraction: the first approximation is the sixth even approximation of the infinite continued fraction for π and the second varies from the first in the ninth term. Both approximations differ in the 13th place. Among these Japanese mathematicians were presumably Shinsuke Seki Kowa, named also Takakazu (16401708) who in 1700 had found 10 places, Takebe Hikojiro Katahiro Kenko (16641739) who in 1722 had found 42 (41 correct) places of π, Kamata Yoshikiyo (16781744) who in 1730 found 25 places and Matsunaga Yoshisuke Ryohitsu, (circa 16391744) who in 1739 had found 51 places of π with the same method as Isaac Newton in 1665 with a series arcsin (1/2) = π/6:
where for such precision we have to take about 140 terms. First approximations of infinite continued fractions of this series are:
His method of calculating π is still mentioned today. Although he worked in subjects like ballistic, physics and astronomy, his major contributions are to the mathematics of the second half of the 18th century.
In 1781 Vega tried to push futher his idea in the Austrian Habsburg monarhy about the usage of the decimal metric system of units. His idea was not accepted, but it was introduced later under the emperor Franz Josef I in 1871.
Jurij Vega was a member of the Academy of Practical Sciences in Mainz, the Physical and Mathematical Society of Erfurt, the Bohemian Scientific Society in Prague, and the Prussian Academy of Sciences in Berlin. He was also an associate member of the British Scientific Society in Göttingen. He was awarded the Order of Maria Theresa on May 11, 1796. In 1800 Jurij Vega obtained a title of hereditary baron including the right to his own coat of arms.
The Slovene PTT has issued a stamp honouring Jurij Vega and the National Bank of Slovenia has issued a 50 Tolar banknote, also in his honour.
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