Longitude rewards

From Hispanopedia
Longitudes and latitudes of the Earth

The longitude rewards were a system of incentive prizes, first offered by King Philip II of Spain in 1567, for a simple and practical method of accurately determining the geographic longitude of ships on the high seas. Philip II initially offered 6,000 ducats to whoever discovered such a method.[1]

His son Philip III, after acceding to the throne in 1598, increased the prize: in addition to the 6,000 ducats, he offered a further 2,000 ducats as a lifetime annuity and 1,000 ducats for expenses. The call drew a great response, and leading figures of the time such as Galileo Galilei entered. Although the prize was ultimately never awarded, the initiative served to explore two methods. One relied on measuring the elapsed time exactly, which was technically difficult at the time. The other calculated an approximation through lunar eclipses observed from different places on Earth. This second method was eventually adopted by the institutions of the Spanish Empire, which was able to implement it because its numerous overseas possessions gave it the logistics needed to set up astronomical observatories at different points on the planet, whose tasks included calculations of lunar eclipses.

These were not the only rewards offered to solve this problem, although they were the first. The States General of the Netherlands offered 10,000 florins in the 17th century,[2] and the United Kingdom offered its own rewards much later, starting in 1714.

Background: the longitude problem

Main article: History of longitude

Measuring longitude became a problem once transoceanic voyages began to be made with relative frequency. Determining latitude was relatively easy, since it could be found from the altitude of the sun at noon with the help of a table giving the sun's declination for each date.[3] For longitude, the first ocean navigators had to rely on dead reckoning, based on calculations of the ship's course and speed over a given time (many of which relied on the intuition of the Captain and/or the navigator). This procedure was inaccurate on long voyages far from the coast, which sometimes ended in tragedy. An accurate determination of longitude was also needed to know the proper "magnetic declination," that is, the difference between the magnetic north shown by the compass and true north, which can differ by as much as 10 degrees in the main trading latitudes of the Atlantic and Indian oceans. Finding a suitable solution for determining longitude at sea was therefore of the utmost importance.

The need for better navigational accuracy on increasingly long ocean voyages had been explored by many European nations for centuries. Spain, Portugal and the Netherlands offered financial incentives for solutions to the problem of geographic longitude as early as 1598.[4]

Astronomical Observation Plan

In 1554 Alonso de Santa Cruz, Chief Cosmographer under the reigns of Charles I and Philip II of Spain, was summoned to Valladolid, where the court of the Regent Prince Philip was located, to take part in a Junta of cosmographers and astrologers charged with addressing the calculation of longitudes. That junta resulted in the writing of the Libro de las Longitúdines y manera que hasta ahora se ha tenido de navegar[5] (Book of Longitudes and the manner in which navigation has been carried out until now), addressed to Philip II, by then King, the first systematic study of the longitude problem.[6] Philip II strictly forbade the publication and distribution of Santa Cruz's work, to prevent it from falling into the hands of rival European powers (although it was naturally taught at the Casa de Contratación), and it was only made public in 1921.

After Santa Cruz's death, Juan López de Velasco took charge. He conceived and carried out an Observation Plan based on calculation by lunar eclipses, which was to be carried out over years by several dozen royal cosmographers, mathematicians and other officials throughout all the dominions of Philip II. They recorded every circumstance surrounding the eclipse they observed, such as the start time, the duration, the intensity (total or partial) and the shadow on an instrument. In this way a relative approximation could be calculated for specific navigation, which served to locate geographically (latitude and longitude) all the territories and the position of each in relation to the others.

The General Archive of the Indies holds two sets of documents that constitute the only graphic documentation of lunar eclipse observations to have survived to the present day. They are the records of an eclipse observation made in Mexico City and another in Puerto Rico.

Thanks to the data received, López de Velasco was able to plot the "Carreras de las Indias" (Indies routes) and the sailing times of each route: from Seville to Sanlúcar de Barrameda, from Sanlúcar de Barrameda to the Canary Islands, from the Canary Islands to La Deseada, from the Lesser Antilles to Cuba, from Cuba to Veracruz, from the Lesser Antilles to Cartagena and Nombre de Dios and from that port to Havana, from San Juan de Ulúa to Havana, from Havana to the Azores and from the Azores to Sanlúcar de Barrameda. He was also able to describe the other routes: from Spain to the Río de la Plata and the Strait of Magellan, the voyages of the South Sea from New Spain, and from there to the Far East.

Bibliography

  • de Grijs, Richard. "Premios Europeos de Longitud I. Determinación de la Longitud en el Imperio Español". Revista de Historia y Patrimonio Astronómico 23, no. 3 (2020): 465–94.
  • Dunn, Richard and Rebekah Higgitt, eds. Empresas de navegación en Europa y sus imperios, 1730-1850. London: Palgrave Macmillan, 2016.
  • Portuondo, María M. La ciencia secreta: la cosmografía española y el Nuevo Mundo. Chicago: University of Chicago Press, 2009. (IsisCB)
  • Randles, WGL "Intentos portugueses y españoles de medir la longitud en el siglo XVI". Vistas en Astronomía 81, no. 4 (1995): 235–41. (IsisCB)

See also

References

  1. ↑ La longitud como coordenada geográfica. Asociación Española de la Marina Civil
  2. ↑ Bell, A.E. (1950). The Life of Christian Huygens. Edward Arnold, London. p. 35.
  3. ↑ In the northern hemisphere, latitude can also be determined from the angle of the Pole Star above the horizon. However, since the Pole Star is not exactly above the pole, latitude can only be estimated unless the exact time is known or many measurements are taken over time. While many measurements can be taken on land, this makes it an impractical method for determining latitude at sea.
  4. ↑ Andrewes, William J.H. (1996). "Introduction". The Quest for Longitude: The Proceedings of the Longitude Symposium: 1–10.
  5. ↑ «Libro de las longitudines y manera que hasta agora se ha tenido en el arte de navegar, con sus demostraciones y ejemplos dirigido al muy alto y poderoso señor Don Phelippe II de este nombre Rey de España» Alonso de Santa Cruz, Cosmógrafo Mayor
  6. ↑ Cuesta Domingo, pp. 31–32.
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