On April 29, 1785, German inventor Karl Drais was born, who invented the Laufmaschine ("running machine"), also later called the velocipede or draisine, also nicknamed the dandy horse
On April 19, 1943, Swiss chemist Albert Hofmann in the Sandoz (now Novartis) laboratories in Basel, Switzerland performed a self-experiment to determine the true effects of LSD, intentionally ingesting 0.25 milligrams (250 micrograms) of the substance, an amount he predicted to be a threshold dose (an actual threshold dose is 20 micrograms). While riding home on his bicycle, he experienced the very first LSD trip, now referred to as “Bicycle Day”, and proved that he had indeed made a significant discovery.