William Strutt, FRS (1756–1830) was a cotton spinner in Belper, Derbyshire, England, and later a civil engineer and architect, using iron frames in buildings to make them fire-resistant.

He also inherited his father's mechanical abilities and is said to have thought of the self-acting mule some years before Richard Roberts patented it in 1830, but the technology was not available to make it work.

He was co-founder of the Derby Philosophical Society with Thomas Gisborne, Richard French, Erasmus Darwin and other individuals, and was President for twenty-eight years.

He rebuilt Belper North Mill after it burnt down in 1803 using an iron-framed structure pioneered by Charles Bage at Ditherington in Shrewsbury.

Sylvester documented the new ways of heating hospitals that were included in the design and the healthier features such as self-cleaning and air refreshing toilets.

The President of the Royal Society eulogised Strutt in 1831 as "author of those great improvements in the construction of stoves, and in the economical generation and distribution of heat, which have of late years been so extensively and so usefully introduced in the warming and ventilation of hospitals and public buildings".

[3] R. S. Fitton, Alfred P. Wadsworth (1958): The Strutts and the Arkwrights, 1758-1830: A Study of the Early Factory System, Manchester University press.