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100 Greatest Science Discoveries of All Time: Levers and Buoyancy

Year of Discovery: 260 B.C. What Is It? The two fun da men tal prin ci ples un der ly ing all phys ics anden gi neer ing.Who Dis cov ered It? Ar chi me desWhy Is This One of the 100 Great est?The con cepts of buoy ancy (wa ter pushes up on an ob ject with a force equal to theweight of wa ter that the ob ject dis places) and of le vers (a force push ing down on one side ofa le ver cre ates a lift ing force on the other side that is pro por tional...

MYSTERY MAN

A trove of fossils found deep in a South African cave adds a baffling new branch to the human family tree.  Conjured in clay and cast in silicone by paleoartist John Gurche, Homo naledi is the newest addition to our genus. MARK THIESSEN, NGM STAFF BY JAMIE SHREEVE  •  PHOTOGRAPHS BY ROBERT CLARK (National Geographic - October 2015) On September 13, 2013, two recreational cavers named Steven Tucker and Rick Hunter entered a dolomite...

Pigeons Make Flight Plans

Though their head-bobbing walk may be comical, pigeons in flight are no fools. They’re urban artful dodgers, threading their way among buildings and other obstacles. David Williams and his Harvard University colleagues studied the birds’ maneuvers to learn how they avoid collisions. First Williams trained wild pigeons to fly through an empty corridor. Then he placed vertical poles at intervals in the corridor and videotaped the birds in the altered...

PUZZLE 001 - Arithmetic & Algebraic Problems

Source: 536 PUZZLES & CURIOUS PROBLEMS by Henry Ernest Dudeney Introduction Henry Ernest Dudeney (the last name is pronounced with a long "u" and a strong accent on the first syllable, as in "scrutiny") was England's greatest maker of  puzzles. With respect to mathematical puzzles, especially problems of more than trivial mathematical interest, the quantity and quality of his out­ put surpassed that of any other puzzlist before or since,...