SUMMARY / RELATED TOPICS

Muzzleloader

A muzzleloader is any firearm into which the projectile and the propellant charge is loaded from the muzzle of the gun. This is distinct from the more popular modern designs of breech-loading firearms; the term "muzzleloader" applies to both rifled and smoothbore type muzzleloaders, may refer to the marksman who specializes in the shooting of such firearms. The firing methods and mechanism further divide both categories as do caliber. Modern muzzleloading firearms range from reproductions of sidelock and percussion long guns, to in-line rifles that use modern inventions such as a closed breech, sealed primer and fast rifling to allow for considerable accuracy at long ranges. Modern mortars use a shell with the propelling primer attached at the base. Unlike older muzzleloading mortars, which were loaded the same way as muzzleloading cannon, the modern mortar is fired by dropping the shell down the barrel where a pin fires the primer, igniting the main propelling charge. Both the modern mortar and the older mortar were used for high angle fire.

However, the fact that the mortar is not loaded in separate steps may make its definition as a muzzleloader a matter of opinion. Muzzleloading can apply to anything from cannons to pistols but in modern parlance the term most applies to black powder small arms, it but not always, involves the use of a loose propellant and projectile, as well as a separate method of ignition or priming. In general, the sequence of loading is to put in first gunpowder, by pouring in a measured amount of loose powder mostly by using a powder flask, or by inserting a pre-measured bag or paper packet of gunpowder or by inserting solid propellant pellets; the gunpowder used is black powder or black powder substitutes like Pyrodex. Sometimes two types of gunpowder were used consisting of finer priming powder for the flash pan and coarser powder for the main charge behind the ball; this was the case with earlier muzzleloaders like matchlocks but appear to have been less common with flintlocks and was irrelevant with percussion locks since they used percussion caps rather than priming powder.

Wadding is made from felt, cloth or card and has several different uses. In shotguns, a card wad or other secure wadding is used between the powder and the shot charge to prevent pellets from dropping into the powder charge and on top of the shot charge to hold it in place in the barrel. In smooth bore muskets and most rifles used prior to cartridges being introduced in the mid-to late nineteenth century, wadding was used to hold the powder in place. On most naval cannons, one piece of wadding was used to hold the powder in place and served the purpose of creating a better seal around the shot. Another was used to act as a plug to stop the shot rolling out because of the swaying of the ship; the use of cartridges with both gunpowder charge and ball, made up in batches by the shooter or a servant, was known from early on, but until around 1800 loading using a powder flask and a bag of balls was more common outside of the military. The measuring stage for the barrel charge of gunpowder could be avoided by carrying a number of pre-measured charges in small containers of wood, metal or cloth carried on a bandolier.

These were known by various names, including "chargers" or "apostles" as 12 were carried. For most of the time muzzleloaders were in use, a round ball and pre-measured powder charge could be carried in a paper or cloth wrapping; the shooter would bite off the end of the paper cartridge with his teeth and pour the powder into the barrel followed by the ball encased in the paper wrapping. The projectiles and wads were pushed down into the breech with a ramrod until they were seated on the propellant charge. Priming powder could be carried in a separate priming flask and poured into the priming pan or a little powder from the cartridge was used, the frizzen was pushed down to hold the priming powder in place. After the gunpowder and projectile or shot charge were placed in the barrel a ramrod was used to pack everything down at the base of the barrel. Either a priming charge was placed in the priming pan or a percussion cap was placed on the nipple, the firing mechanism initiated. Muzzleloading firearms use round balls, cylindrical conical projectiles, shot charges.

In some types of rifles firing round ball, a lubricated patch of fabric is wrapped around a ball, smaller than the barrel diameter. In other types of round ball firing rifles, a ramrod and hammer is used to force the round ball down through the rifling; when fired, either the lead ball or the wrapping grips the rifling and imparts spin to the ball which gives improved accuracy. In rifles firing Minié balls, the patch the paper wrapping from the cartridge, is used as an initial seal and to hold powder in place during loading; the Minié ball replaced the round ball in most firearms military, in the 1840s and 1850s. It has a hollow base; the combination of the spinning Minié ball and the consistent velocity provided by the improved seal gave far better accuracy than the smoothbore muzzleloaders that it replaced. When aiming for great accuracy, muzzle-loaders are cleaned before reloading, so that there is no residue left in the barrel to reduce accuracy, though in competitions run by the international governing body, the MLAIC, this is pr

Tetrahedral-icosahedral honeycomb

In the geometry of hyperbolic 3-space, the tetrahedral-icosahedral honeycomb is a compact uniform honeycomb, constructed from icosahedron and octahedron cells, in a icosidodecahedron vertex figure. It has a single-ring Coxeter diagram, is named by its two regular cells. A geometric honeycomb is a space-filling of polyhedral or higher-dimensional cells, so that there are no gaps, it is an example of the more general mathematical tiling or tessellation in any number of dimensions. Honeycombs are constructed in ordinary Euclidean space, like the convex uniform honeycombs, they may be constructed in non-Euclidean spaces, such as hyperbolic uniform honeycombs. Any finite uniform polytope can be projected to its circumsphere to form a uniform honeycomb in spherical space, it represents a semiregular honeycomb as defined by all regular cells, although from the Wythoff construction, rectified tetrahedral r, becomes the regular octahedron. Convex uniform honeycombs in hyperbolic space List of regular polytopes Coxeter, Regular Polytopes, 3rd.

Ed. Dover Publications, 1973. ISBN 0-486-61480-8. Coxeter, The Beauty of Geometry: Twelve Essays, Dover Publications, 1999 ISBN 0-486-40919-8 Jeffrey R. Weeks The Shape of Space, 2nd edition ISBN 0-8247-0709-5 Norman Johnson Uniform Polytopes, Manuscript N. W. Johnson: The Theory of Uniform Polytopes and Honeycombs, Ph. D. Dissertation, University of Toronto, 1966 N. W. Johnson: Geometries and Transformations, Chapter 13: Hyperbolic Coxeter groups

École nationale supérieure des mines de Saint-Étienne

École nationale supérieure des Mines de Saint-Étienne called École des Mines de Saint-Étienne or Mines Saint-Étienne and abbreviated EMSE is one of the French graduate engineering schools training engineers and carrying out industry-oriented research. Its function is to support the development of its students and of companies through a range of courses and fields of research, from the initial training of generalist engineers ingénieurs civils des mines, to PhD teaching; the school was founded in 1816 by a decision of Louis XVIII. For French nationals, admission to Civil Engineer of Mines is decided after competitive examination at the end of preparatory classes, a selective system. Benoît Fourneyron designed the first practical water turbine in 1827. Jean Baptiste Dieudonné Boussingault Christian Brodhag Henri Fayol, a French management theorist. Jules Garnier Mahamadou Issoufou, elected Niger President on March 2011 Tadeusz Nowicki; the puRkwa Prize is an "international prize for the scientific literacy of the children of the planet" awarded annually by the école nationale supérieure des mines of Saint Etienne and the French Academy of Sciences.

The prize is awarded to pioneers in the innovation of general science education in school curricula for children less than 16 years of age. It was launched in 2004 at the initiative of Robert Germinet, the director of the école nationale supérieure des mines of Saint Etienne, comes with an €80,000 monetary award. École nationale supérieure des Mines d'Albi Carmaux École nationale supérieure des Mines d'Alès École nationale supérieure des Mines de Douai École nationale supérieure des Mines de Nancy École nationale supérieure des Mines de Nantes École nationale supérieure des Mines de Paris Official website SPIN Center of Chemical Engineering Saint Etienne Mines alumni union Mines alumni union