Short answers, pulled from the story.
András Mechwart, a Hungarian engineer, unveiled the roller mill in 1874. This invention replaced the ancient tradition of stone grinding with cylindrical steel rollers to crush grain with industrial precision.
The Hungarian high milling process emerged between 1865 and 1872 as a radical upgrade to traditional stone mills. This method utilized hard Hungarian wheat to create superior flour that secured the First in the world success for the Vienna Bakery at the 1867 Paris Exposition.
Engineers developed complex systems involving five or six rollers to maximize efficiency and purity. A six-roller mill featured three distinct sets of rollers that divided the output into three specific streams while a five-roller mill streamlined the process by having one roller perform double duty.
Roller mills crushed rock, gravel, and ore for the cement industry and the recycling of construction aggregate. These machines also processed specialized materials like pyrophyllite powder for the glass fiber industry and gangue powder for the coal industry.
A dust removal blower was integrated into the system to generate negative pressure at the inlet and outlet of the grinder. This feature prevented dust from escaping and radiated the heat produced by the friction of the rollers to ensure worker safety and machine stability.
The technology spread to mills in Poland where early 20th-century oil-seed roller mills were installed and in West Virginia where a late 19th-century double roller mill was preserved at Cook's Mill. The machine was also found in New York's New Hope Mills Complex where Barnard's Roller Mill stood as a testament to the era's industrial progress.