132 THE OCEAN RIVER 



ous vessels, which was begun by Maury in the middle of the 

 nineteenth century, has continued, and the U. S. Navy Hydro- 

 graphic Office, which carries out the huge task of co-ordinating 

 all such information, has been able to prepare special charts 

 that give the average currents for each month of the year. 

 These are provided for every one-degree square of latitude and 

 longitude, covering 60 miles in each direction. These modern 

 charts and their remarkably few blank squares are in strong 

 contrast to the scanty and generalized information on charts 

 of less than 100 years ago. 



While Pillsbury worked from the American side, several 

 scientific expeditions were made from Europe. Most of them 

 were not organized primarily for current measurement, but 

 they have all contributed more or less to the charting of cur- 

 rents. There were the cruises of the Lightning and the Porcu- 

 pine, and later the celebrated cruise of H.M.S. Challenger 

 covering 69,000 miles in the Atlantic, Pacific, and Antarctic 

 Oceans between 1872 and 1876, under the leadership of 

 Wyville Thompson. Though he was not principally interested 

 in ocean currents, Thompson succeeded — as a later chapter 

 will show — in laying the foundations for the study of the 

 depths of the ocean floor and of the living creatures of the 

 deep sea. The Challenger was followed by the Michael Sars in 

 1910, the Deutschland, the Danish Dana in 1921, and the 

 British Discovery and Discovery 11 between 1925 and 1939. 

 In addition to these were the French vessels Travailleur and 

 Talisman toward the end of the nineteenth century, and the 

 Danish ship Ingolf — to mention only some of the more 

 important. 



Our story has shown that the slow piecing together of the 

 experiences of many men was at first hindered by the poor 

 communication of ideas and always handicapped by the tech- 

 nical difficulties of making direct measurements of such large- 

 scale happenings as currents flowing through the restless sea. 



