Compass, in navigation, an instrument used to indicate directions. It ranks as one of the most important inventions ever made. The usual compass shows the cardinal points—north, east, south, and west—and a number of intermediate points. Most compasses are also graduated in the degrees of a circle, north being 0°; east, 90°; south, 180°; and west, 270°. Surveyors, however, reverse this arrangement and measure clockwise from the south, so that a bearing of 90° in a survey is west.
One person lay in critical condition on Feb. 29, 2008, after the deadly biotoxin ricin was found in his Las Vegas hotel room. What is ricin, and why is it so dangerous?
Pianos lose their tuning, guitars fall out of key -- even church organs need to be tuned every now and then. For centuries, the only sure-fire way to tell if an instrument was in tune was to use a tuning fork.