Conversion from 100 Nautical leagues to Centimeters

Information about the Nautical league (nlea)

The nautical league is a unit of length equal to three nautical miles, or exactly 5556 metres. It is longer than the land league by about 728 metres, since it is built from the nautical mile of 1852 metres rather than the statute mile.

The unit belonged to an era when it was the practical measure of coastal jurisdiction. The cannon shot rule, articulated in the seventeenth and eighteenth centuries, held that a state's authority extended as far as it could defend from shore, conventionally taken as three nautical miles. That distance became the standard territorial sea limit and was expressed as one marine league. Many older treaties and statutes define maritime boundaries in leagues for this reason.

The three-mile limit held for centuries before eroding through the twentieth. States progressively claimed wider waters, and the United Nations Convention on the Law of the Sea settled the matter in 1982 by establishing a twelve nautical mile territorial sea and a two hundred mile exclusive economic zone. Both figures are stated in nautical miles rather than leagues, and the older unit fell out of legal use.

Charts and pilot books from the age of sail used the league routinely for describing offshore distances and the visibility of landmarks. Reading those sources accurately requires knowing which league is meant, since the same word could refer to a land league, a marine league or a Spanish or Portuguese variant, and the differences are large enough to matter when reconstructing a historical position.

Today the unit has no navigational role. Charts are marked in nautical miles, and distances at sea are quoted the same way. The nautical league appears only in historical and legal texts.

The unit also underlies a familiar figure in visibility calculations. From a height of about three metres above sea level, the horizon lies roughly one nautical league away, which is why the three-mile limit corresponded loosely to what a lookout could see as well as to what a gun could reach.

One nautical league equals 3 nautical miles, 5556 metres, 5.556 kilometres, or about 3.452 statute miles.

Information about the Centimeter (cm)

The centimetre is one hundredth of a metre, written cm. Among the metric subdivisions it is the one people reach for most readily in daily life, occupying the range where objects are small enough to hold but too large to measure comfortably in millimetres.

Body measurement is its most common application. Height, waist, chest and inside leg are recorded in centimetres across most of the world, and clothing is sized accordingly. Paediatric growth charts plot height and head circumference in centimetres against age. Rainfall over long periods, snow depth and the dimensions of furniture and luggage are all reported the same way.

The unit had a formal role in science for nearly a century. The centimetre-gram-second system, adopted by the British Association for the Advancement of Science in 1874, took the centimetre as its base unit of length. CGS units such as the erg, the dyne and the gauss were standard in physics until the metre-kilogram-second system displaced them, and SI formally superseded CGS in 1960. Some CGS units persist in astronomy and in parts of electromagnetism.

Volume follows naturally. A cubic centimetre, written cm³ or cc, equals exactly one millilitre. Engine displacement is often quoted in cubic centimetres, particularly for motorcycles, and medical syringes are marked the same way.

Despite its usefulness, the centimetre sits awkwardly in engineering practice. Technical drawings prefer millimetres precisely to avoid mixing units that differ by a factor of ten, since a misplaced decimal point between the two is a plausible and expensive error.

Map scales often make the unit explicit. A 1:25,000 map means one centimetre on the paper represents 25,000 centimetres on the ground, or 250 metres, so four centimetres cover a kilometre. Walkers and orienteers use this relationship constantly, and it is one of the clearer illustrations of why a decimal system is convenient: converting between the two scales requires only moving a decimal point.

Two well-known wavelengths fall in this range and are named by it. Neutral hydrogen radiates at 21 centimetres, a line predicted in 1944 and detected seven years later, and because hydrogen fills the galaxy that single wavelength has mapped the spiral arms of the Milky Way and the rotation curves that first indicated dark matter. Domestic microwave ovens work at 12.2 centimetres, chosen from a band set aside for industrial and medical use rather than for any special resonance with water. In both cases the centimetre is the natural unit because the wave is the size of a hand.

One centimetre equals 10 millimetres or 0.01 metres, and is very close to 0.3937 inches.