Nuclear weapons

The most notable development in weaponry since World War II has been the combination and further development of two weapons first used in it—nuclear weapons and the ballistic missile, leading to its ultimate configuration: the ICBM. The mutual possession of these by the United States and the Soviet Union ensured that either country could inflict terrible damage on the other; so terrible, in fact, that neither nation was willing to instigate direct, all-out war with the other . The indiscriminate nature of the destruction has made nuclear-tipped missiles basically useless for the smaller wars fought since. However computer-guided weaponry of all kinds, from precision-guided munitions to computer-aimed tank rounds, has greatly improved weaponry's accuracy.

Sound recording and reproduction

Sound recording and reproduction is the electrical or mechanical re-creation and/or amplification of sound, often as music. This involves the use of audio equipment such as microphones, recording devices and loudspeakers. From early beginnings with the invention of the phonograph using purely mechanical techniques, the field has advanced with the invention of electrical recording, the mass production of the 78 record, the magnetic wire recorder followed by the tape recorder, the vinyl LP record. The invention of the compact cassette in the 1960s, followed by Sony's Walkman, gave a major boost to the mass distribution of music recordings, and the invention of digital recording and the compact disc in 1983 brought massive improvements in ruggedness and quality. The most recent developments have been in digital audio players like the Apple iPod. New technologies such as Super Audio CD and DVD-A continue to set very hi-fi digital standards.

Swing bridge

A swing bridge is a bridge that has as its primary structural support a vertical locating pin and support ring at or near to its center, about which it can then pivot horizontally as shown in the animated illustration below. Small swing bridges as found over canals may be pivoted only at one end, opening as would a gate, but require substantial underground structure to support the pivot.
In its closed position, a swing bridge carrying a road over a river or canal, for example, allows road traffic to cross. When a water vessel needs to pass the bridge, road traffic is stopped, and then motors rotate the bridge approximately 90 degrees horizontally about its pivot point.