Editing Treaty of Tordesillas (section)

==Tordesillas meridian==
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|File:Early Tordesillas lines.jpg
|Various Spanish and Portuguese reckonings of the Tordesillas line (1495–1545) marked along the [[Brazil]]ian coast, from [[Henry Harrisse|Harrisse]]{{sfnp|Harrisse|1897|p=frontisp}}

|File:CantinoPlanisphere.png
|[[Cantino planisphere]] depicting the meridian, generally considered to represent the Portuguese [[Casa da Índia]]'s official [[Padrão Real]] c.{{nbsp}}1502

|File:Map Diego Ribero 1529.jpg
|The 1529 [[Diogo Ribeiro]] world map, generally considered to represent the [[Padrón Real]] used for deciding the [[Treaty of Zaragoza]]
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The Treaty of Tordesillas only specified the line of demarcation in leagues from the Cape Verde Islands. It did not specify the length of the league, its equivalent in equatorial degrees, or which of the Cape Verde islands was intended. Instead, the treaty provided that these matters were to be settled by a joint voyage. This voyage never occurred, and instead there were only a series of nonbinding expert opinions produced over the next several decades. Their computations were further complicated by remaining uncertainty about the exact equatorial circumference of the earth. As such, each proposed line can be variously computed using geographical leagues defined in terms of a degree using a ratio which applies regardless of the size of the earth or using a [[league (unit)|specifically measured league]] applied to the actual equatorial circumference of the earth, with allowances necessary for the imperfect Portuguese and Spanish knowledge of its true dimensions.{{sfnp|Harrisse|1897|p=194}}
* The earliest Aragonese opinion was provided by Jaime Ferrer in 1495 at the request of Ferdinand and Isabella. He stated to them that the demarcation line was 18° west of the most central island of the Cape Verde Islands, equivalent to 24°25{{prime}} west of [[Greenwich meridian|Greenwich]]. ([[Henry Harrisse|Harrisse]] concludes Ferrer must have meant [[Fogo, Cape Verde|Fogo]] as this central island.) Thus, Ferrer placed the line at 42°25{{prime}} W. on his sphere, which was 21.1% larger than the actual size of the earth. Harrisse further concludes from Ferrer's claim that his league contained 32 Olympic [[stadion (unit of length)|stades]] ({{nowrap|{{cvt|6.15264|km|disp=or}}}}) that his line{{mdash}}if perfectly measured{{mdash}}would have corresponded to a position {{nowrap|{{cvt|2,276.5|km}}}} west of Fogo at 47°37{{prime}} W.{{sfnp|Harrisse|1897|pp=91–97, 178–190}}
* The earliest surviving Portuguese opinion is on the [[Cantino planisphere]] of 1501 or 1502, generally considered to represent the [[Padrão Real|Portuguese standard map]] of its day. Because its demarcation line was midway between Cape Saint Roque, the northeast cape of South America, and the mouth of the [[Amazon River]], labeled the Great River ({{lang|pt|Rio Grande}}) with an estuary marked "All of this sea is fresh water" ({{lang|pt|Todo este mar he de agua doçe}}), Harrisse computed that this line was at 42°30{{prime}} W. on the actual globe. Harrisse believed the large estuary just west of the line on the Cantino map was that of the Rio Maranhão (this estuary is now the [[Baía de São Marcos]] and the river is now the [[Mearim River|Mearim]]), whose flow is so weak that its gulf does ''not'' contain fresh water.{{sfnp|Harrisse|1897|pp=100–102, 190–192}}
* In 1518, another Castilian opinion was provided by [[Martín Fernández de Enciso|Martin Fernández de Enciso]]. Harrisse computes that Enciso's sphere was 7.7% smaller than the actual size of the earth so his line at 47°24{{prime}} W. corresponds to the actual 45°38{{prime}} W. based on his other numerical data. Enciso further described the coastal features near which the line passed, but in a very confused manner that might place the line as far west as the mouth of the Amazon between [[49th meridian west|49°W]] and [[50th meridian west|50°W]].{{sfnp|Harrisse|1897|pp=103–108, 122, 192–200}}
* In 1524, the Castilian mathematician Tomás Durán and [[pilot (ship)|pilots]] [[Sebastian Cabot (explorer)|Sebastian Cabot]] (son of [[John Cabot]]) and [[Giovanni Vespucci|Juan Vespucci]] (nephew of [[Amerigo Vespucci]]) gave their opinion to the [[Conference of Badajoz|conference at Badajoz]], whose failure to resolve the dispute led to the [[Treaty of Zaragoza]]. The pilots specified that the line should be understood as 22° plus about {{nowrap|9 [[Spanish miles]]}} ({{cvt |{{#expr: 9 * 1.3932 }} |km |mi |disp=or|link=out}}) west of the center of [[Santo Antão, Cape Verde|Santo Antão]], the westernmost Cape Verde island. Based on their understanding of the equator, Harrisse concludes they intended 47°17{{prime}} W. on their sphere (3.1% smaller than ours) or 46°36{{prime}}W on the actual globe.{{sfnp|Harrisse|1897|pp=138–139, 207–208}}
* At the same conference, the Portuguese presented a globe on which the line was marked as 21°30{{prime}} west of Santo Antão, which would place it at 47°16{{prime}}52{{pprime}} W. when adjusted to match the actual circumference of the earth,{{sfnp|Harrisse|1897|pp=207–208}} nearly identical to the Spanish suggestion. However, the Badajoz conference disbanded without reaching any formal settlement on any issue.
* The 1529 [[Treaty of Zaragoza]], agreed to by the Spanish king [[Charles I of Spain|Charles I]] ([[Emperor Charles V]]) and [[John III of Portugal]], implicitly assumes within its measurements of a new eastern line that the leagues of the two treaties should be understood as a geographical league equivalent to 4/70th of an equatorial degree,{{sfnp|Chardon|1980|p=140}} placing the line between 43°56{{prime}} and 46°18{{prime}} W. depending on the island chosen. Note, however, that the 1529 [[Diogo Ribeiro]] map{{mdash}}generally considered to represent the now-lost [[Padrón Real|Spanish standard map]] used to finalize the agreement at Zaragoza{{mdash}}placed its own delineation of the Tordesillas agreement much further west, around 49°45{{prime}} W.{{sfnp|Harrisse|1897|p=frontisp}}