e solid iron
this would be true, for iron is certainly much heavier than water. But
if the iron is bent up at the edges,--as it is in a dish pan,--it has
to push much more water aside before it goes under than it would if it
were flattened out. The water displaced, or pushed aside, would have
to take up as much room as was taken up by the pan _and all the empty
space inside of it_, before the edge would go under. Naturally this
amount of water would weigh a great deal more than the empty pan.

But suppose you should fill the dish pan with water, or suppose it
leaked full. Then you would have the weight of all the water in it
added to the weight of the pan, and that would be heavy enough to push
aside the water in which it was floating and let the pan sink. This is
why a ship sometimes sinks when it springs a leak.

You may be able to see more clearly why an iron ship floats by this
example: Suppose your iron ship weighs 6000 tons and that the cargo
and crew weigh another 1000 tons. The whole thing, then, weighs 7000
tons. Now that ship is a big, bulky affair and takes up more space
than 7000 tons of water does. As it settles into the water it pushes
a great deal of water out of the way, and after it sinks a certain
distance it has pushed 7000 tons of water out of the way. Since the
ship weighs only 7000 tons, it evidently cannot push aside more than
that weight of water; so part of the ship stays above the water, and
all there is left for it to do is to float. If the ship should freeze
solid in the water where it floated and then could be lifted out of
the ice by a huge derrick, you would find that you could pour exactly
7000 tons of water into the hole where the ship had been.

But if you built your ship with so little air space in it that it took
less room than 7000 tons of water takes, it could go clear under the
water without pushing 7000 tons of water aside. Therefore a ship of
this kind would sink.

The earth's gravity is pulling on the ship and on the water. If the
ship has displaced (pushed aside) its own weight of water, gravity is
pulling down on the water as hard as it is on the ship; so the ship
cannot push any more water aside, and if there is enough air space in
it, the ship floats.

Perhaps the easiest way to say it is like this: Anything that is
lighter than the same volume of water will float; since a cubic foot
of wood weighs less than a cubic foot of water, the wood will float;
since a quart of