288 
An apparatus has been devised by Messrs. Latham and Way by 
which the temperature of the water may be rendered nearly 
uniform throughout the year. It consists of a tube sunk or driven 
into the ground to a depth of about 25ft,, the water to be cooled 
being admitted at the top and withdrawn at the bottom of the 
tube for the supply of the house. With this arrangement it has 
been found that the variation of the temperature of the water has 
been reduced to 3° throughout the year; this apparatus would 
probably be too expensive for the majority of private houses, but 
in many cases, such as for drinking fountains, would be invaluable. 
The next source of supply is that from springs.—In cases where 
springs, fed by the infiltration of rain water, falling upon a large 
area, occur in abundance, and of the requisite quality, they may 
be held to offer the most desirable sources of supply, particularly 
in cultivated districts, because it is impossible to exclude drainage 
water from entering superficial watercourses, such as are used for 
supplying large reservoirs. 
Of course it is important to ascertain the yield of the springs 
during a long succession of seasons. The Cycle of the climate in 
England is supposed to be of about 17 years’ duration, and indica- 
tions derived from gaugings over short periods are likely to prove 
inisleading ; the time of year will also affect the correctness of the 
observation. The most advisable time to measure the discharge, if 
taken within short periods, is during September and October, for 
durivg these months the springs are generally at their lowest. 
Springs may be divided into two classes—land springs, and 
deep-seated springs—according to the structure of the district from 
which they take their supply. 
Land springs are fed by waters falling upon loose permeable 
materials, lying upon a retentive substratum, through the former 
of which they descend until impeded by the latter, such waters 
not being under pressure do not rise above the ground. 
Deep-seated springs derive their supply from the exposed 
surface of a stratum at a high level, then passing under an im- 
