Eduard Penkala, best known in Croatia and the world for his invention of the mechanical pen, was a Croatian inventor and chemical engineer. Although born in the Slovak town of Liptovsky St. Mikulaš, upon his arrival in Zagreb in 1900, immediately fell in love with him. He liked the city and the environment in which he lived and worked so much that he named his name Slavoljub. In addition to the mechanical pen for which he himself cast thin graphite mines, he enriched the world with over 80 patented inventions. The solid ink fountain pen is certainly one of the more famous. Penkala developed the ink himself and later added a clip to the fountain pen, a simple invention with which the fountain pen can be attached to the pocket and thus prevent ink from spilling on the pocket. Clips can be found on almost all pencils today, whether mechanical or chemical.
One of his first inventions was the hot water bottle, the forerunner of today's thermos bottle. He invented the rotary toothbrush for his daughter who refused to brush her teeth because of the rough brush. Anode battery, laundry detergent, insect repellent, anti-parasite preparation in railway sleepers are just some of his inventions of a chemical nature, and after his death sketches were found for a so-called perpetual dynamo battery whose prototype he never managed to produce due to lack highly qualified masters in Zagreb at the time.
He enriched physics with a manometer, dynamometer and systems for measuring fluid flow. His ambitious project would have to be his own plane. He had the idea for its construction from an early age, and he began constructing it in 1908 in Zagreb. The main idea was that it could be operated by anyone, without special training and preparation. At that time, he could often be seen working on it at the military training ground between Selska cesta and the Črnomerec stream, where he built a hangar. It became a kind of sensation for curious citizens of Zagreb.
Only 7 years after the first flight of the Wright brothers, in 1910 Dragutin Novak took off in Penkala's plane - the first Croatian plane. He also contributed to music of which he was a passionate lover. He perfected the ebonite mass used to cast gramophone records, and he also patented an extended-life gramophone needle. Penkala was and remains a world-famous inventor, and apart from Croatia, in many other countries the name Penkala has remained synonymous with the mechanical pen.