OCEANIC DISCOVERIES. 291 



verj slowly, owing to its vicinity to the south pole of the 

 ecliptic. The Southern Cross began to become invisible in 

 52° 30' north latitude 2900 years before our era, since, accord- 

 ing to Galle, this constellation might previously have reached 

 an altitude of more than 10°. When it disappeared from the 

 horizon of the countries on the Baltic, the great pyramid of 

 Cheops had already been erected more than five hundred years. 

 The pastoral tribe of the Hyksos made their incursion seven 

 hundred years earlier. The past seems to be visibly nearer 

 to us when we connect its measurement with great and mem- 

 orable events. 



The progress made in nautical astronomy, that is to say, in 

 the improvement of methods of determining the ship's place 

 (its geographical latitude and longitude), was simultaneous 

 with the extension of a knowledge of the regions of space, al- 

 though this knowledge was more the result of sensuous observ- 

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

 course of ages to favor 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 skillful application of astrono- 

 my to the ship's reckoning — must all be regarded as power- 

 ful means toward the opening of the different portions of the 

 earth, the more rapid and animated furtherance of general in- 

 tercourse, and the acquirement of a knowledge of cosmical re- 

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

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

 nautical instruments capable of determining the time by the 

 altitude of the stars were in use among the seamen of Cata- 

 lonia and the island of Majorca, and that the astrolabe de- 

 scribed by Raymond Lully in his Arte de Navegar was almost 

 two hundred years older than that of Martin Behaim. The 

 importance of astronomical methods was so thoroughly appre- 

 ciated in Portugal, that toward 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 nav 

 igating by the meridian altitude of the sun was even at "ihat 



• Barros, Da Asia, Dec. i., liv. iv., cap. 2 (1788), p. 282 



