The first successful U.S. satellite, Explorer I, was launched into Earth orbit by the Army on Jan. 31, 1958, at Cape Canaveral, Florida, four months after Russia orbited Sputnik. The 18-pound satellite had a cylindrical shape and was 80 inches long and six inches in diameter.

Explorer I’s small package of instruments produced the first major discovery of the Space Age—The Van Allen radiation belts surrounding the Earth. Explorer I burned up in the atmosphere on March 30, 1970.

A chronograph is a timepiece capable of measuring discrete elapsed time units as well as telling time in a 12-hour format. In such a watch, each of these two separate time-keeping functions operates independently. This means that one typically contains a mechanism for regular time-keeping as well as a separate movement for the stopwatch, or elapsed time, function. A chronograph should be distinguished from a chronometer, which is a timepiece that is officially certified for its high degree of accuracy.

Pocket watch chronographs were produced as early as the 18th century but did not become popular until the 1820s.  The term ‘Chronograph’ is often confused with the term ‘Chronometer’ which in some cases designates a watch that has received a precision certification. The Marine chronometer was an accurate timepiece used to enable celestial navigation.

Altimeter: an apparatus used in aircraft for measuring altitudes.
Ammeter: is used for to measure intensity of sound.
Anemometer: is an instrument for measuring the force and velocity of wind.
Audiometer: an instrument to measure intensity of sound.
Audiophone: is an instrument required for improving imperfect sense of hearing.