ARTESIAN WELLS, named after Artois, the ancient Artesium, a French province, where the method of boring was first adopted in Europe. A bore hole is carried down into water bearing strata, and the water, in certain formations, rises by hy drostatic pressure, or is pumped up. There is a well within the old Carthusian convent at Lillers which has been flowing since the 12th century. Traces of more ancient bored wells appear in Lombardy, in Asia Minor, Persia, China, Egypt, Algeria, and in the Sahara desert. Very big yields are often obtained; for instance, a set of eight wells at Camber well, London, give a million and a half gallons per day. A large variety of tools is employed in the work of boring, some rotary, some percussive, and their opera tion is effected with hand plant, or by power. A derrick is erected on the spot to suspend the rods from, and carries the winding drum, and, in rotary plants, an engine for turning the rods. The diagram shows a percussive plant, with the chisel seen well into the water-bearing strata. Changes in tools have to be made according to the strata encountered; in some instances a rotary crown of diamonds, costing thousands of pounds, has to be used to bore through rock. Lining-tubes, which range from 3 in. to 24 in. or more in diameter are driven down as the bore progresses, while permanent lining-tubes are put in for the passage of the fluid. This is therefore only able to rise from the water-bearing strata, no surface percolations gaining access. The use of a continuous casing, or pipe, insures this. Depths reach to as much as 2,5ooft. in some cases.
Several kinds of pumps are applied to the duty of raising water, some being reciprocating, worked from a crankshaft at the top, and operating a bucket with flap or lift valves, in conjunction with a foot-valve. As the bucket rises the water is sucked up through the foot-valve, and as it descends the foot-valve shuts, and those in the bucket open to pass the water upwards. The driving is done by belt, steam-engine, internal-combustion engine, or electric motor. Latterly multi-stage turbine pumps have been installed to an increasing extent, while the compressed-air method, forcing up the water without any moving mechanism below, is much utilized. The turbine pumps are driven in some instances direct by a vertical electric motor on the top end of the shaft, and this goes down through a tube jointed up in sections, with lignum-vitae bearings, which are lubricated by the water itself, as it flows through the tube to the delivery outlet at the top. (See PUMPS; AIR LIFT.)