the origin of horsepower

James Watt did use the concept of horsepower to compare steam-engine output with the work of horses. His calculations of a horse’s power date to around 1782, and the measure became part of Boulton & Watt’s commercial language during the 1780s. I found no reliable source establishing 1789 as the first use of the term itself. The date in the source item is therefore unverified; the idea arose earlier. The illustration is AI-generated.