Word: wood
(lookup in dictionary)
(lookup stats)
Dates: all
Sort By: most recent first
(reverse)
...that is an illusion. The mirror is really a pool of liquid mercury in a shallow wood container. A touch would send ripples racing across its surface, and it must always aim straight up to retain its curvature. As the container is slowly rotated on a turntable; making one revolution every six seconds, the mercury rises gently toward the edges and dips in the middle, the way coffee does when it is stirred in a cup. In perfect deference to the laws of physics, the metal's highly reflective surface takes the form of a parabola, the shape of solid...
Borra emphasizes that the concept of a liquid-mirror telescope is not new; he thinks the idea may have occurred to Isaac Newton, who knew about the behavior of spinning fluids and built one of the first reflecting telescopes. Borra knows that Robert Wood of Johns Hopkins University built a primitive model in 1908. "I am not the inventor," says Borra. "But I am the first to make it work and the first to know what to do with...
...Wood's problem was that the motors of his day could not turn at a constant enough rate of speed. As a result, the curvature of his mirror kept changing. Also he was unable to avoid vibrations, which set up ripples in the metallic pool. Wood was aware of another shortcoming of his telescope: because it always had to face straight up, it could not be swung around to point at interesting stars and galaxies or to take time-exposure photographs by following the celestial objects across the sky as the earth rotated...
...book, The Power of Play, a lamentation on the gradual replacement of toy trucks and dollhouses with "robo pets and battery-operated cars," which "don't leave much to the imagination." (But didn't the toy truck seem outrageously modern to a Victorian who grew up playing with wood blocks and marbles?) Similarly, in its journal this month, the American Academy of Pediatrics protests the ebb of recess, arguing that "undirected play allows children to learn how to work in groups, to share, to negotiate, to resolve conflicts ..." But most schools--at least 70%--haven't cut recess. And according...
...sainthood. Or at least Dean’s List. Name at least the titles of every other book Hume wrote; don’t just say Medieval cathedrals, name nine. Think up a few specific examples of “contemporary decadence,” like Natalie Wood. If you can’t come up with titles, try a few sharp metaphors of your own; they at least have the solid clink of pseudo-facts...