FIGURE S1.1 Track of the HMS Challenger Expedition 1872-1876. TALLEY Copyright © 2011 Elsevier Inc. All rights reserved FIGURE S1.1

Overturning circulation of the Atlantic Ocean according to Merz and Wüst (1923). TALLEY Copyright © 2011 Elsevier Inc. All rights reserved FIGURE S1.2

FIGURE S1.3 Meteor after refit. Source: From Spiess (1928). TALLEY Copyright © 2011 Elsevier Inc. All rights reserved

FIGURE S1.4 Ekman repeating current meter. Source: From Spiess (1928). TALLEY Copyright © 2011 Elsevier Inc. All rights reserved