AN ACCOUNT OF THE RISE OF NAVIGATION. 1 



By R. H. Curtiss. 



One of the most obvious practical benefits directly traceable to 

 astronomical research is found in the application of celestial observa- 

 tions to the solution of the problems of navigation. Though other 

 sciences have contributed their quota, it is mainly astronomy that has 

 made the ocean safe for the navigator. 



The fundamental problem of navigation is : Given the position on 

 the earth of the port to be reached, to determine the ship's positions 

 and the best courses to be steered at suitable intervals from the begin- 

 ning to the consummation of the voyage. This problem, so important 

 commercially, is, strictly speaking, one of science, for it depends 

 chiefly for its accurate solution on the application of the principles 

 and methods of practical astronomy. 



For obvious reasons the accuracy attainable in determinations of 

 position and direction at sea is much inferior to that possible on 

 shore. The unsteadiness of the platform of a ship, the uncertainties 

 of atmospheric refraction near or on the horizon, and the intervention 

 of cloudy periods while the ship is progressing through disturbing 

 currents and winds are formidable difficulties which the navigator 

 must meet. But the results attainable with care leave only a small 

 element of risk affecting modern transportation at sea. 



Quite different was the position of the navigator in early times. 

 The compass was introduced generally into Europe about 1400 A. D. 

 Before this time the only practical means of navigating a ship on 

 the Atlantic and Mediterranean was to keep in sight of land, or 

 occasionally, for short distances, to direct the ship's course by refer- 

 ence to the sun and stars. But this latter rough method failed in 

 cloudy weather, and even during short voyages on the Mediterranean 

 in such circumstances the navigator became hopelessly bewildered as 

 to his position. Frequently on the China Sea and the Indian Ocean 

 vessels were able to traverse long distances out of sight of land 

 by running directly before the steady winds, called the monsoons, 

 which prevail in those localities. But the compass was an important 



1 Reprinted by permission from Popular Astronomy, Vol. XXVI, No. 254, April, 1918. 

 The author expresses acknowledgements especially to the United States Hydrographic 

 Office and the Encyclopedia Brlttanica for material used in this article. 



127 



