670 COSMOS. 



ous with the extension of a knowledge of the regions of space, 

 although this knowledge was more the result of sensuous ob- 

 servation than of scientific induction. All that was able in the 

 course of ages to favour advance in the art of navigation the 

 compass and the more correct acquaintance with magnetic 

 declination; the measurement of a ship's speed by a more 

 careful construction of the log and by the use of chronometers 

 and lunar observations ; the improved construction of ships ; 

 the substitution of another force for that of the wind; and 

 lastly, and most especially, the skilful application of astronomy 

 to the ship's reckoning, must all be regarded as powerful 

 means towards the opening of the different portions of the 

 earth, the more rapid and animated furtherance of general 

 intercourse, and the acquirement of a knowledge of cosmical 

 relations. Assuming this as one point of view, we would again 

 observe, that even in the middle of the thirteenth century nau- 

 tical instruments capable of determining the time by the altitude 

 of the stars, were in use among the seamen of Catalonia and 

 the Island of Majorca, arid that the astrolabe described by Ray- 

 mond Lully in his Arte de Navcgar, was almost two hundred 

 years older than that of Martin Behaim. The importance of 

 astronomical methods was so thoroughly appreciated in 

 Portugal, that towards the year 1484, Behaim was nominated 

 President of a Junta de Mathematicos, who were to form 

 tables of the sun's declination, and, as Barros observes, to 

 teach pilots the method of navigating by the sun's altitude, 

 maniera de navegar por altura del Sol.'* This mode of navi- 

 gating by the meridian altitude of the sun was even at that 

 time clearly distinguished from that by the determination of 

 the longitude, por la altura del Este-0este.\ 



The importance of determining the position of the 

 papal line of demarcation, and of thus fixing the limits 

 between the possessions of the Portuguese and Spanish crowns 

 in the newly discovered land of Brazil, and in the group 

 of islands in the South Indian Ocean, increased, as we 

 have already observed, the desire for ascertaining a practical 

 method for determining the longitude. Men perceived how 

 rarely the ancient and imperfect method of lunar eclipses 



* Barros, da Asia, Dec. i. liv. iv. cap. 2 (1788), p. 282. 



f* Navarrete, Coleccion de los Viages y Descubrimientos que hicieron 

 por mar los Espaholes, t. iv. p. xxxii. (in the Noticia biographica de 

 Fernando de Magellanes) 



