US Patent 1,068,781, an internal-combustion engine design assigned to the K D Motor Company.
On July 29, 1913, Margaret Knight, then 75 years old, was granted US Patent 1,068,781 for an internal-combustion engine design. The patent was assigned to the K D Motor Company, indicating a formal business relationship through which Knight's late-career automotive engineering work was being commercially developed.
This patent represents a continuation of the engineering trajectory she had begun over a decade earlier with her rotary engine series. Internal combustion technology was, at this time, rapidly displacing steam and electric power as the dominant automotive propulsion method, and Knight's continued contributions in this space placed her squarely within one of the most consequential technological transitions of the industrial age.
The K D Motor Company assignment suggests Knight had established herself as a serious contributor to a formal engineering enterprise even in the final year of her life, rather than working as an isolated hobbyist inventor. Remarkably, this was not her final patent in this field — a packing-ring patent would follow just months later, in February 1914, and a further internal-combustion engine patent would be granted posthumously in 1915. Taken together, these late-life patents demonstrate that Knight remained an active, engaged inventor literally until her death, a rare and notable trajectory for any inventor of either sex in this era.