a view seems quite conclusive to whomever is not obstinate, since it is proved that the diversity of the relative positions of the superior bodies proceeds from the difference between the places of observation.
Supposing that the number of miles or leagues corresponding to each degree were to be verified by the care and skill of the men abovesaid, then another very long and difficult calculation would be necessary, namely, the appointment of experienced men to measure and determine the number of measures or degrees from one continent or province to another. And when they shall reach the half [one hundred and eighty degrees] counting from the line passing at the end of the three hundred and seventy leagues, at that place they shall establish a point or mark to show what pertains to each side. But as this manner of measuring degrees may be difficult from east to west, although easy from north to south, recourse must be had to certain fine and subtile methods, of which, although everybody is well informed concerning them, I shall not hesitate to state a few facts I have been able to acquire, in order to give these other deputies an opportunity to explain those facts of which I am ignorant.
[Various methods for estimating the length of a degree follow. Colon concludes thus:]
But inasmuch as the determination of the above methods seems to be and is difficult, each one of them must be employed, and each one put into execution, so long as one does not conflict with the other. Furthermore the day's run must conform to these methods, and pilots of great experience and judgment chosen. In this way it might be hoped to determine a division in which neither part would suffer any
