A vigia is a warning on a

nautical chart A nautical chart is a graphic representation of a sea area and adjacent coastal regions. Depending on the scale of the chart, it may show depths of water and heights of land (topographic map), natural features of the seabed, details of the coa ...

indicating a possible rock,

shoal In oceanography, geomorphology, and geoscience, a shoal is a natural submerged ridge, bank, or bar that consists of, or is covered by, sand or other unconsolidated material and rises from the bed of a body of water to near the surface. It ...

, or other hazard which has been reported but not yet verified or

surveyed Surveying or land surveying is the technique, profession, art, and science of determining the land, terrestrial Two-dimensional space#In geometry, two-dimensional or Three-dimensional space#In Euclidean geometry, three-dimensional positions of ...

. Some non-existent vigias have remained on successive charts for centuries as a precaution by hesitant hydrographers. One such example was 'Las Casses Bank', a vigia between

Menorca Menorca or Minorca (from la, Insula Minor, , smaller island, later ''Minorica'') is one of the Balearic Islands located in the Mediterranean Sea belonging to Spain. Its name derives from its size, contrasting it with nearby Majorca. Its capi ...

and

Sardinia Sardinia ( ; it, Sardegna, label=Italian, Corsican and Tabarchino ; sc, Sardigna , sdc, Sardhigna; french: Sardaigne; sdn, Saldigna; ca, Sardenya, label=Algherese and Catalan) is the second-largest island in the Mediterranean Sea, after ...

in the

Mediterranean Sea The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ea ...

which first appeared on charts in 1373 and remained on some charts as late as 1852. Another notable false vigia was ' Aitkins' Rock' off the northwest coast of Ireland, first reported in 1740 with six further reports over the following eighty years the supposed rock was blamed for numerous lost ships. Surveys by the

Royal Navy The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against F ...

in 1824, 1827, and 1829 failed to locate the rock, until a final extensive six week survey in 1840 using two

brigs A brig is a type of sailing vessel defined by its rig: two masts which are both square rig, square-rigged. Brigs originated in the second half of the 18th century and were a common type of smaller merchant vessel or warship from then until the ...

led to the conclusion that the rock had never existed. Captain

Alexander Thomas Emeric Vidal Alexander Thomas Emeric Vidal (1792 – 5 February 1863) was an officer of the Royal Navy. He became an accomplished surveyor, and reached the rank of vice-admiral. Early life Vidal was born in 1792, the youngest of four children of Emeric Vidal ...

, who led the final survey, noted that such false sightings were likely due to floating debris or whales. The term vigia is derived from the Spanish ''vigía'' or Portuguese ''vigia'', from the Latin ''vigilia''''.''

References

{{Reflist Cartography Hydrography Phantom islands

See also

References