38 The Sea 
The physical law of floating is that the buoyant force 
exerted upon a ship is equal to the weight of the water dis- 
placed. Salt water, being denser than fresh water, weighs 
more for a given volume and hence exerts a greater buoyant 
force. The law is said to have been first discovered by the 
ancient Greek mathematician, Archimedes (287-212 B.C.). 
He discovered the law while in the bath, and in his delight 
ran home naked shouting “Eureka!.Eureka!” Besides having 
accomplished his fundamental theoretical work in hydraulics, 
Archimedes was quite a hand at practical matters. He in- 
vented machines to use against the Romans in the siege of 
Syracuse. He built long range catapults (early “flame throw- © 
ers) for throwing fiery brands into enemy ships, machines 
for discharging volleys of arrows through openings in the 
walls, long movable poles that projected out over the water 
and dropped heavy weights on the enemy's vessels. One ma- 
chine could grapple a vessel with an iron hook, lift it up 
partly out of the water, and then drop it again. 
The enemy leader, Marcellus, chided his own engineers 
with the following pettharies: 
“Shall we not make an end of fighting against fins geo- 
metrical Briareus, who uses our ships as cups to ladle water 
from the sea, drives off our sambuca ignominiously with 
cudgel-blows and, by the multitude of missiles that he hurls 
at us all at once, outdoes the hundred-handed giants of my- 
thology?” 
Archimedes met his death on the seashore while making 
a geometrical diagram in the sand. A conquering Roman sol- 
dier approached him, Archimedes told him to stand aside out 
of the sunlight, at which the soldier became so incensed that 
he drew his sword and slew the old mathematician. 
