9 8 
THE FAIRY-LAND OF SCIENCE. 
beautiful whiteness, is all pressed out, and the snow- 
crystals themselves are squeezed into one solid mass 
of pure, transparent ice. 
Then we have what is called a " glacier," or river of 
ice, and this solid river comes creeping down till, in 
Greenland, it reaches the edge of the sea. There it 
is pushed over the brink of the land, and large pieces 
snap off, and we have " icebergs." These icebergs 
made, remember, of the same water which was first 
drawn up from the tropics float on the wide sea, and 
melting in its warm currents, topple over and over * 
till they disappear and mix with the water, to be car- 
ried back again to the warm ocean from which 
they first started. In Switzerland the glaciers cannot 
reach the sea, but they move down into the valleys 
till they come to a warmer region, and there the end 
of the glacier melts, and flows away in a stream. The 
Rhone and many other rivers are fed by the glaciers 
of the Alps ; and as these rivers flow into the sea, our 
drop of water again finds its way back to its home. 
But when it joins itself in this way to its com- 
panions, from whom it was parted for a time, does 
it come back clear and transparent as it left them? 
From the iceberg it does indeed return pure and clear; 
for the fairy Crystallization will have no impurities, 
not even salt, in her ice-crystals, and so as they melt 
they give back nothing but pure water to the sea. Yet 
even icebergs bring down earth and stones frozen into 
* A floating iceberg must have about eight times as much ice 
under the water as it has above, and therefore, when the lower 
part melts in a warm current, the iceberg loses its balance and 
tilts over, so as to rearrange itself round the centre of gravity. 
