Newton’s Rings

When a curved glass surface, such as a convex lens, is placed against a flat piece of glass and illuminated by monochromatic light, a series of alternating bright and dark concentric bands, known as Newton’s rings, appears around the point of contact between the curved and flat glass. Though several scientists had observed the phenomenon before him, it was named for Isaac Newton, who analyzed it in detail. Why are the outer rings usually spaced more closely together than the inner rings? Discuss
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Charles Francis Hall

Hall was an American explorer of the Arctic. In the 1860s, he made two notable—but mostly unsuccessful—searches for Sir John Franklin’s lost expedition. In 1871, he attempted to reach the North Pole. Though he set a new northern record, he died suddenly before reaching the pole. Later, 19 members of his crew became stranded on an ice floe for several months before being rescued. It is now believed that Hall was likely murdered, but it is also possible that he accidentally poisoned himself—how? Discuss
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Elizabeth of Bohemia

The daughter of James I of England, Elizabeth was married to elector palatine Frederick V in 1613 to cement an alliance between English and German Protestantism. She became queen of Bohemia when her husband accepted the crown in 1619, but after his defeat by the Catholic League the next year, they went into exile. Her descendents founded the House of Hanover, which ruled England for nearly 200 years. What failed plot would have put nine-year-old Elizabeth on the English throne had it succeeded? Discuss
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The Blowgun

A blowgun is a hollow tube out of which a dart or an arrow is blown. The projectile is usually tipped with a poison, like curare, to stun or kill prey. Usually used for hunting and rarely in warfare, blowguns vary in length from 18 in (45 cm) to over 23 ft (7 m) and are often crafted from cane or bamboo. The arrows, made to fit snugly in the gun’s tube, are fashioned from palm leaf midribs or bamboo splinters. Blowguns were widely used by prehistoric peoples and are still used in what locations? Discuss
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The Gang of Four

The Gang of Four was an alliance of four Chinese political officials who rose to prominence during the Cultural Revolution but were later imprisoned for implementing the harsh policies of Mao Zedong, fomenting widespread civil unrest, and attempting to seize power. They had the youthful Red Guard persecute intellectuals and suppress a wide variety of traditional cultural activities. A month after Mao’s death in 1976, the four were arrested. Among them was Mao’s third wife. What happened to her? Discuss
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