[s. E. DAWSox] THE LINES OF DEMARCATION 543 



there it is necessary that the said vessel change and take her course along 

 said line in the direction of the Antarctic pole up to that point where the 

 Arctic pole is fifteen degrees in elevation, and then at that exact end will be 

 the end of the line or parallel which passes through the said Cape Verde and 

 at the end and true terminus of the said 370 leagues; which terminus is very 

 clearly indicated by the elevation of the North star according to tne 

 aforesaid rule. 



5. And because the sailing chart is not wholly useful and does not suffice 

 for the mathematical demonstration of the above rule, a world map in spheri- 

 cal form is necessary, divided into two hemispheres by its lines and degrees, 

 and the situation of the laud, islands and sea, each in its own place — which 

 world map I put down together with these expressions of my meaning and 

 opinion, the more clearly to demonstrate the truth. 



And I say that to understand the above rule and practical method it is 

 necessary to be a cosmographer, arithmetician and navigator, or to under- 

 stand the art; and he who does not possess all these three sciences, cannot 

 possibly understand (the rule) nor (can he succeed) by any other way or rule 

 if he is not expert in the three said sciences. 



6. And for a further exposition of the above rule it must be known that 

 the quarter of the wind (point of the compass) the vessel takes as its course, 

 starting from the Cape Verde islands at the end of the 370 leagues, will be 

 distant from the western parallel or line seventy-four leagues at the rate of 

 twenty per cent, and because the said quarter (of the wind-rose or compass) 

 inclines towards the North sailing by it the different (increasing) elevation 

 of the pole-star is clearly apparent, and the said seventy-four leagues com- 

 prise three degrees and a third of latitude, very nearly. 



7. It is, moreover, to be noted that pursuing the above rule it is neces- 

 sary to give to each degree seven hundred stadia, according to Strabo, Alfra- 

 gano, Teodoci, Macrobi, Ambrosi and Euristhenes (Eratosthenes) ; since 

 Ptolemy gives only five hundred stadia to a degree. And I say further that 

 there is another method of finding the said terminus according to the practice 

 and science of mariners, and it is as follows. 



8. First, let the sovereigns our lords and the King of Portugal take twenty 

 mariners, ten for each side, the best to be found, and conscientious men, and 

 let them start in one vessel from the Cape Verde islands on a westerly line, 

 and let each one of the said mariners note with great care on his chart, every 

 six hours, the course the vessel makes according to his judgment; and, hav- 

 ing been bound under oath, let none of them communicate his opinion to 

 another until the first of the mariners who in his judgment finds himself at 

 the said terminus shall state so to two captains — men of reputation, put on 

 board the said vessel by the will and accord of the said sovereigns. And let 

 the said captains then take the opinions and judgments of the other mariners 

 and, if the rest agree with the first who finds himself at the terminus, let them 

 take his decision as conclusive and final as to the said terminus; and if they 

 do not agree with the first, let them take the opinion and judgment of the 

 majority, and after agreeing, let them change the course on a straight line 

 towards the Antarctic pole, and everything they find on the left hand towards 

 Guinea shall belong to the King of Portugal in the manner above stated. 



This second method is uncertain and may be erroneous because it is 

 based on the simple and sole judgment and opinion of mariners, and the first 

 rule is very certain, (that one) by the elevation of the North star, as is shown 

 above. 



9. And if in this my decision and opinion any error appear, I will always 

 defer to the correction of those who know and understand more than I, 

 especially to the Admiral of the Indies, who at the present time knows more 

 than any other person in this subject, for he is greatly learned in the theory 

 and admirably practical, as his famous achievements demonstrate ; and I 

 believe that Divine Providence holds him as elect to carry out its great 

 mystery and service in this undertaking, which I believe is the disposition 

 and preparation of that (result) which, hereafter, the same Divine Providence 

 will manifest to its great glory— the salvation and good of the world. 



10. Here is shown the navigation of the Admiral of the Main-land. 

 Ptolemy in the eighth book de situ orbis says at chapter five: 



'V*- 



