I also like https://technicshistory.com/2021/02/18/the-age-of-steam-introduction/ https://technicshistory.com/2021/02/18/the-age-of-steam-intr..., which points

I also like https://technicshistory.com/2021/02/18/the-age-of-steam-introduction/ https://technicshistory.com/2021/02/18/the-age-of-steam-intr..., which points in part to metal purity and engineering tolerances.