A DROP OF WATER. 91 
turning into water, and the bright spot in the middle 
is a bubble of empty space, left because the watery 
flower does not fill up as much room as the ice of the 
crystal star did 
Fig 23. 
tVater-flowers in melting ice. Tvndall. 
And this leads us to notice that ice always takes 
up more room than water, and that this is the reason 
why our water-pipes burst in severe frosts ; for as the 
water freezes it expands with great force, and the pipe 
is cracked, and then when the thaw comes on, and 
the water melts again, it pours through the crack the 
ice has made. 
It is not difficult to understand why ice should take 
more room ; for we know that if we were to try to 
arrange bricks end to end in star-like shapes, we must 
leave some spaces between, and could not pack them 
so closely as if they lay side by side. And so, 
when this giant force of crystallization constrains 
the atoms of frozen water to grow into star-like 
forms, the solid mass must fill more room than 
