Horsepower, as a unit of measurement, originated in the late 18th century. The concept was developed to quantify the power of steam engines, specifically to demonstrate their benefit compared to working horses. One PS (Pferdestärke) represents the power needed to lift 75 kilograms by one meter in one second. This measurement wasn't purely scientific, however; it served as a marketing tool for James Watt, the inventor of the improved steam engine. By relating the engine's power to the familiar strength of a horse, Watt aimed to make its capabilities more easily understood and appealing to potential buyers in Great Britain. The unit’s adoption facilitated the comparison of engine output to the labor force available at the time, solidifying its place in engineering and industry.