Toyota Corona Mark II

Speed measurement? Overrated! Especially in the early days of car manufacturing. The development of the speedometer began in 1902. Initially, cars were so slow that their speed could be gauged with the senses. Acceleration and movement were still easily perceptible with the five senses. There was just no precise measure for speed. On October 7, 1902, Otto Schulze patented a method in Berlin that could accurately measure speed. A magnet was rotated by a shaft connected to the car's wheel. Above the magnet was a rotatable metal disc with an indicator. The rotating magnet induced eddy currents in the metal hood, which the metal disc wants to follow. Due to a special spring brake, only a slight rotation occurred instead of a complete rotation. With increasing rotation of the magnet, the force of the eddy currents increased, causing the indicator to display a higher speed on the proportional scale. This speedometer was initially an expensive extra. However, by 1910, Ford decided to offer this instrument as standard. Accidents increased, and authorities had to respond with speed limits.