A DROP OF WATER. 97 
substances brought down into the sea. It is with 
lime and magnesia that the tiny chalk-builders form 
their beautiful shells, and the coral animals their 
skeletons, while another class of builders use the flint ; 
and when these creatures die, their remains go to 
form fresh land at the bottom of the sea ; and so, 
though the earth is being washed away by the 
rivers and springs it is being built up again, out 
of the same materials, in the depths of the great 
ocean. 
And now we have reached the end of the travels of 
our drop of water. We have seen it drawn up by the 
fairy ". heat," invisible into the sky ; there fairy " co- 
hesion " seized it, and formed it into water-drops, and 
the giant, " gravitation," pulled it down again to the 
earth. Or, if it rose to freezing regions, the fairy of 
" crystallization " built it up into snow-crystals, again 
to fall to the earth, and either to be melted back into 
water by heat, or to slide down the valleys by force 
of gravitation, till it became squeezed into ice. We 
have detected it, when invisible, forming a veil round 
our earth, and keeping off the intense heat of the sun's 
rays by day, or shutting it in by night. We have seen 
it chilled by the blades of grass, forming sparkling 
dew-drops or crystals of hoar-frost, glistening in 
the early morning sun ; and we have seen it in the 
dark underground, being drunk up greedily by the 
roots of plants. We have started with it from the 
tropics, and travelled over land and sea, watch- 
ing it forming rivers, or flowing underground in 
springs, or moving onwards to the high mountains 
or the poles, and coming back again in glaciers and 
