Curta. A Curta mechanical calculator Curta A partially disassembled Curta calculator, showing the digit slides and the stepped drum behind them Curta Type I calculator showing view from top Curta Type I calculator showing view from bottom Curta (Type I) mechanical calculator shown in the operational position (left hand). The Curta is a small, hand-cranked digital mechanical calculator introduced by Curt Herzstark in 1948.
The Curta's design is a descendant of Gottfried Leibniz's Stepped Reckoner and Thomas's Arithmometer, accumulating values on cogs, which are added or complemented by a stepped drum mechanism. Curtas were considered the best portable calculators available until they were displaced by electronic calculators in the 1970s.[1] History[edit] The Curta was conceived by Curt Herzstark (1902–1988) in the 1930s in Vienna, Austria. Herzstark, the son of a Catholic mother and Jewish father, was taken into custody in 1943, eventually finding himself at the Buchenwald concentration camp.
T-Shirts. ThisIsWhyImBroke.com - ThisIsWhyImBroke is where you'll find cool gift ideas, unique products, and awesome birthday and christmas gift ideas. With hundreds of reasons to spend every penny you've got, ThisIsWhyImBroke features amazing products you can buy. Bismuth crystal. Bismuth is a chemical element with symbol Bi and atomic number 83. Bismuth, a pentavalent other metal, chemically resembles arsenic and antimony. Elemental bismuth may occur naturally, although its sulfide and oxide form important commercial ores.
The free element is 86% as dense as lead. It is a brittle metal with a silvery white color when freshly produced, but is often seen in air with a pink tinge owing to surface oxidation. Bismuth is the most naturally diamagnetic element and has one of the lowest values of thermal conductivity among metals. Bismuth metal has been known from ancient times, although until the 18th century it was often confused with lead and tin, which share some physical properties. Bismuth compounds account for about half the production of bismuth. History[edit] The name bismuth is from ca. 1660s, and is of uncertain etymology. Characteristics[edit] Bismuth crystal illustrating the many iridescent refraction hues of its oxide surface Physical characteristics[edit] Snorg Tees - New Funny T-Shirts Every Week (Vintage T-Shirt, Cool Graphic Tee Shirts) Geeky Gifts.