Furthermore navigation charts shall be made by them, in which the said line shall be drawn in the manner aforesaid, so that henceforth the said vassals, natives, and subjects of the said emperor and king of Castilla shall navigate by them; and so that the navigators of either pa shall be certain of the location of the said line and of the aforesaid distance of the two hundred and ninety-seven and one-half leagues between the said line and Maluquo. It is covenanted and agreed by the said deputies that, whenever the said King of Portugal should wish to prove his right to the proprietorship of Maluco, and the lands and seas specified in this contract, and although at that time the said emperor and king of Castilla shall not have returned the price abovesaid, nor the said contract be canceled, it shall be done in the following manner, namely, each one of the said sovereigns shall appoint three astrologers and three pilots or three mariners who are experts in navigation, who shall assemble at a place on the frontier between the kingdoms, where it shall be agreed that they assemble, within four months of the time when the emperor and king of Castilla, or his successors, shall be notified by the said King of Portugal to appoint a day. There they will consult, covenant, and agree upon the manner of ascertaining the right of said proprietorship conformable to said treaty and contract made between the said Catholic sovereigns, Don Fernando and Doña Isabel, and the said King Dom Joam the Second of Portugal. In case the said emperor and king of Castilla be judged to have the right of said proprietorship, such sentence will not be executed nor used until the said emperor and king of Castilla or his successors shall first have actually returned all the said three hundred and fifty thousand ducats, which by virtue of this contract shall have been given. If the right of proprietorship be conceded to the said King of Portugal, the said emperor and king of Castilla or his successors shall be obliged actually to return the said three hundred and fifty thousand ducats to said King of Portugal or his successors within the first four years ensuing after the date of such sentence.