Gravitation 25 



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. 



