Tusi couple An animated model of a Tusi couple. Original description Tusi's diagram of the Tusi couple If two coplanar circles, the diameter of one of which is equal to half the diameter of the other, are taken to be internally tangent at a point, and if a point is taken on the smaller circle—and let it be at the point of tangency—and if the two circles move with simple motions in opposite direction in such a way that the motion of the smaller [circle] is twice that of the larger so the smaller completes two rotations for each rotation of the larger, then that point will be seen to move on the diameter of the larger circle that initially passes through the point of tangency, oscillating between the endpoints.  Creation Nasir al-Din al-Tusi, born in the town of Tus in 1201, is acknowledged throughout the Islamic world as one of the 'Great Wisdoms'. Other sources There are other sources for this mathematical model for converting circular motions to reciprocating linear motion.
Russian Revolution - Facts & Summary The February Revolution (known as such because of Russia’s use of the Julian calendar until February 1918) began on March 8, 1917 (or February 23 on the Julian calendar), when demonstrators clamoring for bread took to the streets in the Russian capital of Petrograd (now called St. Petersburg). Supported by huge crowds of striking industrial workers, the protesters clashed with police but refused to leave the streets. On March 10, the strike spread among all of Petrograd’s workers, and irate mobs destroyed police stations. On March 11, the troops of the Petrograd army garrison were called out to quell the uprising. The imperial government was forced to resign, and the Duma formed a provisional government that peacefully vied with the Petrograd Soviet for control of the revolution.
A History of Arabic Astronomy: Planetary Theories During the Golden Age of Islam - George Saliba - كتب Google A History of Arabic Astronomy is a comprehensive survey of Arabic planetary theories from the eleventh century to the fifteenth century based on recent manuscript discoveries. George Saliba argues that the medieval period, often called a period of decline in Islamic intellectual history, was scientifically speaking, a very productive period in which astronomical theories of the highest order were produced. Based on the most recent manuscript discoveries, this book broadly surveys developments in Arabic planetary theories from the eleventh century to the fifteenth. Taken together, the primary texts and essays assembled in this book reverse traditional beliefs about the rise and fall of Arabic science, demonstrating how the traditional “age of decline” in Arabic science was indeed a “Golden Age” as far as astronomy was concerned. To students of European intellectual history, the book reveals the technical relationship between the astronomy of the Arabs and that of Copernicus.
Hypothesis A hypothesis (plural hypotheses) is a proposed explanation for a phenomenon. For a hypothesis to be a scientific hypothesis, the scientific method requires that one can test it. Scientists generally base scientific hypotheses on previous observations that cannot satisfactorily be explained with the available scientific theories. Even though the words "hypothesis" and "theory" are often used synonymously, a scientific hypothesis is not the same as a scientific theory. A working hypothesis is a provisionally accepted hypothesis proposed for further research. The adjective hypothetical, meaning "having the nature of a hypothesis", or "being assumed to exist as an immediate consequence of a hypothesis", can refer to any of these meanings of the term "hypothesis". Uses In Plato's Meno (86e–87b), Socrates dissects virtue with a method used by mathematicians, that of "investigating from a hypothesis Scientific hypothesis Working hypothesis See also Notes
PC Architecture. A book by Michael B. Karbo - a book by Michael Karbo. This book is protected by copyright. It has been published in many European countries but never in English language. These web pages have been produced from a Microsoft Word file. PC Architecture. Leonardo da Vinci Leonardo is revered for his technological ingenuity. He conceptualised flying machines, an armoured vehicle, concentrated solar power, an adding machine, and the double hull, also outlining a rudimentary theory of plate tectonics. Relatively few of his designs were constructed or were even feasible during his lifetime,[nb 2] but some of his smaller inventions, such as an automated bobbin winder and a machine for testing the tensile strength of wire, entered the world of manufacturing unheralded.[nb 3] He made substantial discoveries in anatomy, civil engineering, optics, and hydrodynamics, but he did not publish his findings and they had no direct influence on later science. Life Childhood, 1452–1466 Leonardo's earliest known drawing, the Arno Valley (1473), Uffizi Verrocchio's workshop, 1466–1476 Professional life, 1476–1513 In 1482 Leonardo, who according to Vasari was a most talented musician, created a silver lyre in the shape of a horse's head. Old age, 1513–1519 Personal life
Sustainable Human This video was produced as a gift to humanity by Sustainable Human (sustainablehuman.me). Visit us to find out how you can support and create videos like How Whales Change Climate in collaboration with a global team of volunteers. Together, we can change the story of the world. Visit the official landing page for more information on this incredible story: sustainablehuman.me/how-whales-change-climate "When we try to pick out anything by itself, we find it hitched to everything else in the Universe." - John Muir When whales were at their historic populations, before their numbers were reduced, it seems that whales might have been responsible for removing tens of millions of tonnes of carbon from the atmosphere every year. Credits: Editor: Steve Agnos (bit.ly/1zHaiFl) Producer: Chris Agnos (bit.ly/1bmB8KK) Narration: George Monbiot Music Credits: Cylinder 2 - Chris Zabriskie (bit.ly/1ya8Z4x) Dramatic Film Strings (Cinematic Movie Soundtrack) – Ramazan Yuksel (bit.ly/1CwDMeR) Film Credits: