Friedrich Paul Jacobi

Friedrich Paul Jacobi (born May 8, 1727 in Tucheband / Neumark ; † June 8, 1758 in Olmütz ) was a Prussian lieutenant in the artillery and teacher of mathematics in the artillery corps, member of the Royal Prussian Academy of Sciences .

Lineage and Scientific Education

His parents were the pastor Adam Friedrich Jacobi (1697–1781) from Tucheband, son of the pastor Friedrich Jacobi (1642–1744), and his wife Sophie Magdalene Meyer, daughter of the Lippe government councilor Lic.jur. and advocate in Hanover Johann Ludwig Meyer, Assessor of Justice in Hildesheim and advisor to Count zu Schaumburg Lippe.

Friedrich Paul Jacobi and his somewhat younger brother August Johann Jacobi, who later became the judiciary in Königsberg, received their first training from their grandfather Friedrich Jacobi and learned the Greek and Latin languages, history and geography, as well as the basics of theology and the Hebrew language. The training was continued at the college in Küstrin, which was headed by the Rector Helmereich.

From 1744 the brothers attended the university in Halle. They studied theology with Siegmund Jakob Baumgarten . Friedrich Paul Jacobi continued his studies in Hildesheim to study law. But he was also interested in mathematics. After a discussion with his father, he decided not to continue studying theology or law, but wanted to be a soldier with the gunner in Berlin, to which the father agreed.

With whom Jacobi was married is unknown. He was the father of Colonel Jacobi, who had passed away in 1820.

Membership in the learned coffee house

Jacobi became a member of the Scholars' Association of Scholars Coffee House , which existed in Berlin from 1755 to probably 1759. The members included a. the mathematicians Franz Ulrich Theodor Aepinus (1724–1802), Johann Albrecht Euler (1734–1800), the Jewish-German philosopher Moses Mendelssohn (1729–1786), the writer, publisher , critic , author of satirical novels and travelogues, regional historians, main representatives the Berlin Enlightenment Christoph Friedrich Nicolai (1733–1811) and the later Prussian Colonel of the Artillery Karl Friedrich von Moller (1690–1762). In a note on a letter from Mendelssohn to Lessing dated March 9, 1756, who visited the philosopher Alexander Gottlieb Baumgarten (1714–1762) with the “Lieutenant Jacobi” and found him “a very skilled man, a good mathematician and thorough Metaphysician ”, Nicolai described that Jacobi was an accurate head and an excellent mathematician. Jacobi knew Baumgarten from the time he was studying in Halle. At the Society's meetings, Jacobi gave a lecture “about lifting tools”.

Military activity

Jacobi sought out Colonel Johann Friedrich von Merkatz (1698 to 1763) in Berlin, who accepted him as a non-commissioned officer in his company. Jacobi was able to prove that he was good at anything to do all the duties of a soldier. He showed courage and loyalty and took part in the capture of Leipzig and in the battle of Kesselsdorf near Dresden. The battle of Kesselsdorf decided the war in Prussia's favor. The Saxons and Austrians were defeated.

Jacobi wrote a description of this battle, "the first in which he participated". In doing so, he showed his disgust for the looting. But he found himself unable to protest against it.

In February 1746 Jacobi was transferred to the "Company of Bombardiers" of Colonel Ernst Friedrich von Holtzmann (deceased 1759). In his free time he devoted himself to studying mathematics and physics. He developed special skills in this, so that his superior, Lieutenant Otten, instructed him to instruct the soldiers in weapons technology and land surveying. Before and after the Silesian Wars, under Frederick the Great, the regimental colleges worked diligently to train prospective artillerymen. Johann Heinrich von Holtzmann (the brother of Ernst Friedrich von Holtzmann) and Jacobi, whose collegium, which had been held since 1747, and probably earlier, has probably been lost, made a particular contribution to the education. From July 1749 Jacobi had the advantage of getting to know the Prussian field marshal and Grand Maitre of the artillery Samuel Graf von Schmettau (1684–1751), who was also the curator of the Academy of Sciences . At a demonstration of new weapons, Jacobi gave the marshal, who had also invited Leonhard Euler (1707–1783) and Johann Kies (1713–1781) to the event, a proof of his weapons technical skills.

In 1745 Euler had translated a work by the Englishman Benjamin Robins into German with his own commentary on the results of new research on ballistics and the advantages of rifled barrels. This work dealt with the new principles of artillery, in particular the determination of the force of the powder along with an investigation into the difference in the resistance of the air in fast and slow movements. Euler endeavored in this translation to provide an applicable solution to the problem of air resistance. Based on Euler's ballistic analysis of 1753, Jacob not only calculated the 18 tables proposed by Euler, but created a total of 36 tables. He has carried out numerous experimental studies of mortar and cannon firing trajectories with a view to air resistance, and the relationship between speed, mass and angle of influence

When in 1751 two of his essays on ballistics were presented to the Prussian King Frederick the Great , he was promoted to lieutenant. Jacobi was ordered by the king because of his knowledge in the philosophical and mathematical sciences to instruct the "senior officers as fireworkers and bombardiers". A real artillery academy was not established in Prussia until 1791. Before the Seven Years' War (1756–1763) and afterwards, however, there were so-called Collegia, which were visited by officers, NCOs, fireworks and bombing. In 1754 the so-called "Jacobische Collegium" was established, which was directed by Jacobi. Frederick the Great called the lessons given since Jacobi the "artillery school". At the age of 28 he became a full member of the Royal Prussian Academy of Sciences in 1752 . Jacobi was the first to deal seriously and thoroughly with the trajectory of projectiles in his lectures. He took into account the fall of bodies in free space, the resistance of the air and the initial velocity of the projectiles. He showed that in order to achieve a greater probability of hitting it was necessary to use the strongest in combination with the smallest elevation among all usable charges, and then dealt with the trajectory of the taxiing shot . He made the Riloschettiren, which was probably only introduced around the middle of the 18th century, a special subject of scientific investigation and in 1756 wrote his own treatise on it, in which he also discussed the theories of the philosopher , mathematician , physicist and astronomer Galileo Galilei (1564-1641) subjected to an examination. He also wrote a lecture on the use of flat mirrors to observe one's own shots and to record the terrain in front of an attacked front. He also taught to find the attachment from the length of the gun and the elevation angle, as well as to find the elevation angle from this and the imaginary length by means of trigonometric operations. In August 1755, King Friedrich II visited a maneuver in Spandau in which mortars were fired. He convinced himself of Lieutenant Jacobi's skill, praised him very much and told him that his expectations had been exceeded.

In 1756 Jacobi wrote an extensive work on ricocheting and the rules that would produce the best results if followed. In the second year of the Seven Years' War , Frederick II decided to invade Bohemia and conquer Prague . Jacoby took part in the battle near Reichenberg (April 21, 1757) and the Battle of Prague (May 6, 1757), in which the Prussians were victorious. The Prussians were finally defeated in the Battle of Kolin (June 18, 1757) and suffered their first defeat in the Seven Years' War. During the siege of Olomouc in June 1758, Jacobi was hit by an enemy cannonball and mortally wounded. When Nicolai did the above Comment on the letter Mendelssohn wrote to Lessing, Jacobi had already died.

biography

• Eloge de M. Jacobi, Treatises of the Royal Academy of Sciences in Berlin, 1769, 520ff, digitally in French [9]

Individual evidence

1. ^ Rolf Straubel : Biographical manual of the Prussian administrative and judicial officials 1740–1806 / 15 . In: Historical Commission to Berlin (Ed.): Individual publications . 85. KG Saur Verlag, Munich 2009, ISBN 978-3-598-23229-9 , pp. 456 ( limited preview in Google Book search).
2. ^ Johann David Erdmann Preuss: Friedrich the Great. A life story. Volume 4, Berlin 1834, p. 486ff. digital [1]
3. ^ Karl Lachmann (Ed.): Gotthold-Ephraim Lessing: Sämmliche Schriften. New edition, Volume 13, Berlin 1840, p. 19. (digitized version)
4. ↑ Rainer Falk: Scholarly coffee house. In: Handbook of Berlin Associations and Societies 1786–1815. Berlin 2015, ISBN 978-3-05-006015-6 , pp. 17ff. (on-line)
5. ^ Louis von Malinowsky, Robert von Bonin , History of the Brandenburg-Prussian Artillery , Volume 2, p. 509
6. ↑ Robins, Benjamin; Euler, Leonhard, New principles of artillery: containing the determination of the power of the powder together with an investigation into the difference between the resistance [sic!] Of the air in fast and slow movements, Berlin 1745, digital: [2]
7. ^ Gabriel Christoph Benjamin Busch , Handbook of Inventions, Volume 2, 4th edition, Eisenach 1809, digital [3]
8. ↑ Brett D. Steele, The Heirs of Archimedes: Science and the Art of War Through the Age of Enlightenment, London 2005, p. 365 digital [4]
9. ↑ Brett D. Steele, Rational Mechanics as Enlightenment Engineering: Leonhard Euler and Interior Ballistics, 2005, p. 292 (First presented at the 23rd Symposium of ICOHTEC, Budapest, 1996) [5]
10. ^ Johann Carl Conrad Oelrichs: Contributions to history and literature. Berlin 1760, p. 229. (digitized version)
11. ^ Johann David Erdmann Preuss: Friedrich the Great. A life story. Volume 4, Berlin 1834, p. 486ff. digital [6]
12. ^ Directory of members of the predecessor academies of the Berlin-Brandenburg Academy of Sciences. ( Digitized version , accessed on September 7, 2015)
13. ↑ Louis von Malinowsky, Robert von Bonin, History of the Brandenburg-Prussian Artillery, Volume 2, P. 631ff, digital [7]
14. ^ Carl Julius Cranz, Otto von Eberhard , Karl Emil Becker, Otto Poppenberg, Textbook of Ballistics, Volume 1, Leipzig and Berlin 1910, p. 21, partly digital: [8]
15. ^ Directory of members of the predecessor academies of the Berlin-Brandenburg Academy of Sciences. ( Digitized version , accessed on September 7, 2015)