The Nature of Sea Water 37 
ence greater ease in swimming in salt water than in fresh 
water. 
Ocean liners are buoyed up differently (that is, have a dif- 
ferent water line) in different bodies of water. By interna- 
ae 
BOW OF SHIP 
ae MSOLL MARKS 
a9 
BOW ag BOW OE SHIR, SHIP 
Wi = 
— Ik 
Plimsoll marks appear on each side of hull. Abbreviations mean 
FW Fresh water S Summer 
IS Indian Ocean, summer W Winter 
WNA_ Winter North Atlantic 
tional agreement (International Load Line Convention, 
1930) vessels of 150 gross tons or over must have load lines 
painted on their hulls. This line represents the maximum 
safe draft of the vessel. There are usually different lines for 
different bodies of water because of their different densities. 
