Quern-stones are stone tools for hand-grinding a wide variety of materials. They are used in pairs. The lower stationary stone of early examples is called a saddle quern, while the upper mobile stone is called a muller, rubber or handstone. The upper stone was moved in a back-and-forth motion across the saddle quern. Later querns are known as rotary querns. The central hole of a rotary quern is called the eye, and a dish in the upper surface is known as the hopper. A handle slot contained a handle which enabled the rotary quern to be rotated. They were first used in the Neolithic era to grind cereals into flour.
An old Gaelic proverb is "The quern performs best when the grindstone has been pitted."
The upper stones were usually concave while the lower ones were convex. Quern-stones are frequently identifiable by their grooved working surfaces which enabled the movement of flour. Sometimes a millrind was present as a piece of wood (or other material), which allowed the cereal etc. to be added but still acted as a centering device. The upper stone sometimes had a cup-shaped area around the hopper hole with a raised edge. Most handstones have a handle hole on the upper surface, but one class of quern-stones have a slot handle which indicates that a piece of wood was placed horizontally and protruded out from the edge so that the operator could turn the stone by standing and using a rod vertically. One class of upper quern-stones has from two to three sockets for the rod used to turn them and this is thought to reflect the need to reduce wear and tear by having alternative points of contact when in active use.
Quern-stones have been used by numerous civilizations throughout the world to grind materials, the most important of which was usually grain to make flour for bread-making. They were generally replaced by millstones once mechanised forms of milling appeared, particularly the water mill and the windmill, although animals were also used to operate the millstones.
This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.
A mill is a device, often a structure, machine or kitchen appliance, that breaks solid materials into smaller pieces by grinding, crushing, or cutting. Such comminution is an important unit operation in many processes. There are many different types of mills and many types of materials processed in them. Historically mills were powered by hand or by animals (e.g., via a hand crank), working animal (e.g., horse mill), wind (windmill) or water (watermill). In modern era, they are usually powered by electricity.
A mortar and pestle is a set of two simple tools used to prepare ingredients or substances by crushing and grinding them into a fine paste or powder in the kitchen, laboratory, and pharmacy. The mortar (ˈmɔrtər) is characteristically a bowl, typically made of hard wood, metal, ceramic, or hard stone such as granite. The pestle (ˈpɛsəl, also USˈpɛstəl) is a blunt, club-shaped object. The substance to be ground, which may be wet or dry, is placed in the mortar where the pestle is pounded, pressed, or rotated into the substance until the desired texture is achieved.
A windmill is a structure that converts wind power into rotational energy using vanes called sails or blades, by tradition specifically to mill grain (gristmills), but in some parts of the English-speaking world the term has also been extended to encompass windpumps, wind turbines, and other applications. The term wind engine is also sometimes used to describe such devices. Windmills were used throughout the high medieval and early modern periods; the horizontal or panemone windmill first appeared in Persia during the 9th century, and the vertical windmill first appeared in northwestern Europe in the 12th century.
Dans ce cours introductif à la physique des fluides, l'étudiant commence par apprendre, au moyen de bilans de masse et de contraintes, à décrire et à prédire les écoulements types. Ces méthodes sont a
Covers hydrostatic forces, equilibrium in fluid systems, and solutions to hydrostatic conundrums.
Explores passing by reference in C, deep copying, memory allocation rules, and type differentiation.
Introduces a 'professional' 3D measurement system for stone analysis and feature extraction using stereo photogrammetry and structured light technologies.