TEMPERATURE OF WELLS.
Invariably the temperature of water from great depths is higher than at the surface, this being due to some unknown source of heat in the interior of the globe.
In Scotland, the rate of increase of temperature, after permanent degree has been attained, is about one degree Fahrenheit for every forty-eight feet of descent.
At Grenelle, the temperature was found to be 1.8 degrees for every 106 feet of descent below the point of constant temperature.
The average rate of increase of temperature is one degree for a descent of from forty to fifty feet.
The temperature of the boring at Columbus increased, below the permanent line, one degree in every seventy-one feet.
EXAMPLES OF ARTESIAN WELLS.
The famous well at Grenelle, France, was commenced, by the government, in 1834, and after repeated failures and discouragements almost to abandonment, notwithstanding the urgent representations of the scientist Arago, that water would be found, the end was accomplished at the depth of 1,798 feet, in the year 1843. The diameter of the bore is 3½ inches; capacity, 600 gallons per minute; temperature of water, 82 degrees; height of flow, 128 feet. The expense attending this boring was 300,000 francs. The Passy well, near Paris, supplied from the same water-bearing stratum of the Grenelle, is 1,923 feet deep; 2′ 4″ inches bore at bottom; capacity, 5,582,000 gallons per day; height of flow, 54 feet. The La Chapelle well was started in 1866, with a gigantic bore of five feet seven inches, and by November, 1869, had reached a depth of 1,811 feet, the intention of the engineer being to extend it to a depth of 2,950 feet.
At the part of Paris named Butte-aux-Caelles, a well was started, in 1866, of six and a half feet diameter, to be carried down to a depth of 2,600 to 2,900 feet.
The Kent Water-Works, of London, is supplied by wells in the chalk formation, yielding 9,000,000 gallons daily. This great flow is due to what is known as a fault in the London basin strata.