Calculation table (“Table I”) for anti-aircraft fire, maker: Joseph Bürgin, 1915, 61.9 × 41.2 × 3.4 cm, wood, paper, celluloid, metal. KIT Archives 28508/60.
The panel, consisting of tables and a shiftable reading pointer, was designed as a tool for defense against enemy aircraft during World War I. When the war began, airplanes were quickly developed into a weapon. The city of Karlsruhe was one of the early targets of bombing raids. The first was on June 15, 1915, killing 30 people. Another attack in 1916 killed 120 people, including 71 children. Since 1914, Josef Bürgin (1872–1917), a surveyor at Karlsruhe Polytechnic, had been working on calculation aids for defensive fire. Not only the impact of the war on the civilian population but also the presence of anti-aircraft positions in Karlsruhe may have been a driving force behind his decision to apply his expertise in this way. The problem tackled by Bürgin involves the rapid motion of aircraft in three-dimensional space and their distance away. A flying object traveling at 150 kilometers per hour at a distance of 1,000 meters can cover around 50 meters distance in the time it takes for a projectile to travel from the gun to it. Therefore, anti-aircraft guns are aimed at the point where the projectile and the target will meet. The difference between this and the gun alignment directly on the target is called the lead. Calculating the lead requires an equation that relates distance, direction, and the velocities of both target and bullet. The calculation tables created by Bürgin are an attempt to reduce the time required for this enough to be able to use the result in practice. The lack of signs of wear on the tables created by Bürgin suggests, however, that his tools must have served as models at best. kn