MAGELLANIC CLOUDS. 47 



the long duration of Magellan's circumnavigation (from Au- 

 gust, 1519, to September, 1522), and the long sojourn of a 

 numeJ-ous crew under the southern sky, obHterated the re- 

 membrance of all earher observations, and spread the name 

 of the Magellanic Clouds among all the sea-faring nations 

 of the Mediterranean. 



We have thus shown by a single example how the exten- 

 sion of the geographical horizon southward opened a new 

 field to contemplative astronomy. There were four objects 

 to which the attention of pilots was especially directed in the 

 new hemisphere, viz., the search for a southern polar star, the 

 form of the Southern Cross, which assumes a vertical position 

 when it passes through the meridian of the place of observ- 

 ation, the Coal-sacks, and the circling clouds of light. We 

 learn from the treatise on the art of navigation [Arte de Nav- 

 egar, lib. v., cap. 11), by Pedro de Medina, which has been 

 translated into many languages, and first appeared in 1545, 

 that the meridian altitudes of the " Cruzero" were used as 

 early as the first half of the sixteenth century for the determ- 

 inations of latitude. Measurement soon succeeded the mere- 

 ly contemplative observation. The first work on the position 

 of stars contiguous to the antarctic pole was based on the dis- 

 tances of known stars of the Rudolphine Tables, as calcula- 

 ted by Tycho Brahe. This work, as I have already observed,* 

 was composed by Petrus Theodori of Embden, and Friedrich 

 Houtman of Holland, who navigated the Indian Seas about the 

 year 1594. The results of their measurements were speedi- 

 ly embodied in the Star- Catalogues and celestial globes of 

 Blaeuw (1601), of Bayer (1603), and of Paul Morula (1605). 

 Such were the materials for the foundation of the topography 

 of the southern heavens before Halley (1677), and before the 

 meritorious astronomical researches of the Jesuits Jean de 

 Fontaney, Richaud, and Noel. The intimate connection be- 

 tween the history of astronomy and that of geography thus 

 indicates those memorable epochs in which (scarcely two 

 hundred and fifty years ago) men first acquired the knowl- 

 edge necessary for the completion of the cosmical image of 

 the firmament and of the configuration of continents. 



The Magellanic Clouds, the larger of which covers a ce- 

 lestial space of forty-two, and the smaller a space of ten 

 square degrees, certainly produce, at first sight, the same 



the Milky Way throughout the arch of heaven within tho breadth of 

 that space."] 



* Cosmos, vol. ii., p. 287; vol. iii., p. 112, 138. 



