knowledge of time of year and solar declination. This device was limited to use on
days without overcast and was difficult to employ when a ship’s deck was vigorously
pitching. Alternatively, the angles of stars above the horizon in the night sky could
be checked against astronomical tables. Longitude was impossible to measure with
precision until the invention of the first portable chronometer in 1722. The chronom-
eter is a clock that keeps solar-based time for a specified meridian (now
universally the prime meridian). At local noon when the sun is directly over the
meridian, the chronometer is checked. The hours and minutesof time difference
between local noon and the chronometer reading is converted into longitude at the
rate of 15°of longitude per hour. Sextants and chronometers can provide accurate
measurements down to seconds of the geographic grid. There has been a revolution
in latitude/longitude determination. This was enabled by the 1993 launch of the last
of a constellation of 24 geopositioning satellites. Ground units, hand held and inex-
pensive enough to be owned by virtually anyone, can be used to determine latitude,
longitude, and altitude by geometrically determining the angles between the receiver
and—usually four or more—satellites.Law of the Sea
The Law of the Sea refers to a collective body of jurisprudence that has developed
largely over the past three centuries. The fundamental question involved how much
territorialitya state could claim over the sea, as an extension of its shoreline. Some
European countries began claiming a “territorial sea” adjacent to their coastlines in
the late 16th century, but no internationally recognized standard existed, and such
zones were arbitrarily established. As European states became more involved in
maritime commerce and exploration, the indeterminate character of the territorial
sea led to frequent wars, especially between England and the Netherlands. The
two countries fought four wars between 1652 and 1784, and one of the main causes
of this extended string of conflicts was the struggle over control of shipping lanes,
maritime resources, and territorial waters. By the beginning of the 19th century, a
number of countries were claiming a stretch of water adjacent to their coastlines
of three to four nautical miles, although some demanded a somewhat wider swath
of water. No wars erupted from these conflicting claims, although disputes some-
times occurred. Most of these disagreements were resolved by bilateral or multilat-
eral treaties, but it still remained the purview of any sovereign maritime state to
declare and enforce the extent of its territorial waters—no universally accepted
and recognized code governed such claims. The formation of the League of Nations
in the wake of World War I led to greater efforts to establish global standards202 Law of the Sea