132 
EIGHTH REPORT. 
seeds of life thus gathered—for the very reason that they may not 
he in great abundance or variety, thus allowing such as are present 
favorable conditions for development—are likely to increase in num¬ 
bers if the conditions in reference to temperature and light are favor¬ 
able. To prevent farther contamination and especially to exclude mos¬ 
quitoes from cisterns, they should be properly covered. Rain water, 
however, as usually gathered, contains a relatively high percentage of 
inorganic matter either in suspension or in solution, which is liable 
to undergo decomposition, and render it foul and unhealthy to man. 
In order to counteract this tendency as far as practicable, adequate 
ventilation, suitable overflow pipes, and frequent cleansing of cisterns 
should be provided for. In reference to the use of rain water for 
domestic purposes the fact should be borne in mind, as stated above, 
that it is deficient in the mineral matter in solution to an extent 
which for continuous use for drinking, renders it unwholesome. 
When all precautions have been taken to preserve the purity of 
rain water, when desired for domestic use, it is safe to assume that 
it should not be taken internally by man, unless well boiled or thor¬ 
oughly filtered. 
For use as a means of fire protection, rain water is obviously as 
serviceable as water from any other source, and for use in generating 
steam it is no doubt superior to any other water that can be obtained, 
for the reason that its content of mineral matter in solution is far 
below that of average streams and springs. In regions where water 
is scarce and even in humid regions where the streams and springs 
are abnormally high in mineral matter in solution, the construction 
•of gathering grounds for rain water in excess of that supplied by roofs, 
might be advisable and practicable, in order to obtain water for fire 
protection and for generating steam. 
Shallow Wells: In regions where the surface level of soil satura¬ 
tion or the water table, is within approximately fifty feet or less of 
the surface, the obtaining water by means of ordinary dug wells is 
practicable, and such wells may be utilized as a source of municipal 
water supply. The ideal conditions in this connection are; sufficient 
volume of water especially during dry seasons, to be obtained econom¬ 
ically, and also that the water shall be wholesome. 
Shallow wells, however, especially if situated in the vicinity of 
thickly inhabited regions, are always to be viewed with suspicion; and 
in general it is safe to say, such sources of supply should not be 
utilized for municipal purposes except as a last resort. In case it is 
necessary to use them every possible care needs to be taken to decrease 
the dangers of contamination, and the water properly filtered before 
it should be considered suitable for domestic use. The practice some¬ 
times indulged in, of depending on natural filtration during the pro¬ 
cess of percolating into a shallow well, is not wise, as the condition 
and nature of the so-called filter is seldom if ever thoroughly known. 
The chemical nature of the water supplied by shallow wells and 
cold or hill side springs, also demands attention. In many regions 
where such sources of water supply are utilized, the superficial blanket 
of rock waste is highly sandy and the underlying rocks contain but a 
small percentage of easily soluble material, and the water is of a com- 
