554 
POPULAR SCIENCE REVIEW. 
water of tMs pump was the active cause of the outbreak of 
cholera. I bring forward this case now as it may be a timely 
warning_, and also as an illustration of the importance of 
securing, at least for drinking purposes, pure water. 
As an organic being, man requires water for the performance 
of the functions of his life. Water is necessary to the existence 
of the universal world. Eocks and the inorganic substances of 
the earth assume their forms in obedience to the influence of 
water. The great physical features of the earth^s surface have 
been determined by the action of water. As it assumes the 
solid, liquid, and gaseous forms under the influence of heat, it 
is one of the great agents of change upon the surface of the 
earth. Plants and animals may be regarded as organised water. 
There is no life upon the globe without water. Many of the 
lower forms of animal and vegetable hfe consist mainly of 
water. A jelly fish, weighing many pounds, was found to con- 
tain only a few grains of other constituents. All organic matters 
when dead lose a great portion of their weight when exposed 
to heat, on account of the evaporation of the water which they 
contain. 
The life of plants and animals is maintained by the chemical 
changes which go on in their tissues by the agency of the 
organic elements, carbon, hydrogen, oxygen, and nitrogen. But 
these elements are not conveyed into the plant or animal in 
their pure form. The plant takes them up in the form of 
carbonic acid and ammonia. Neither are these compounds 
taken up in their pure form. They are conveyed into the tissues 
of plants by the agency of water. Each drop of rain, as it 
descends for the nourishment of the vegetable kingdom, con- 
tains its quota of carbonic acid and ammonia, and it is the 
water which is absorbed, and which carries into the system of 
the plant these compounds. Not only are the organic elements 
thus carried, but the mineral constituents of plants, the salts of 
lime, soda, and potash, are thus conveyed. Arrest the supply 
of water and all nourishment ceases. 
The same is the case with animals. Not only is water 
necessary for the constitution of their bodies, but all the sub- 
stances which maintain animal heat, and which nourish the 
animal tissues, are dissolved and carried into the body by the 
aid of water. Nay, even when these substances are oxidised 
and changed, and are no longer fitted for the purposes of life, 
they are carried off from the system by the aid of v^ater. 
Man is no exception to this law. His body is composed 
mainly of water. The constituents of a man^s body, weighing 
150 pounds, might be easily divided into five parts, each of 
which could be placed in an ordinary-sized pail, holding 32 
pints. All the solid constituents of a man^s body would go 
