The loose material in the bore is removed by a sand pump. To protect the bore from caving a casing of steel pipe must be lowered into the well. The boring may proceed at the rate of ten to sixty feet per day, depending upon the material penetrated and the depth of the well. All sorts of difficulties are liable to interrupt the work. The cable may break, the string of tools may become unscrewed, or the casing may drop into the hole, and then follows the tedious process of fishing for the lost parts and hauling them up out of the well.
As the drilling proceeds, the bore becomes progressively smaller and casings of smaller diameter must be used. The well is completed by lowering a pipe within the casing through which the oil flows to the surface and is carried to the storage tanks and thence by pipe lines to the refineries.
While the percussive system of drilling is very generally used throughout the American oil fields, rotary methods of drilling are largely employed in California.
CHAPTER XVII
FROM FIBER TO FABRIC
IT IS NOT very long since the spinning wheel and the clacking loom were an indispensable furnishing of every farmhouse and of many city dwellings as well. With infinite patience the fleece of sheep, the lint of flax, the filaments of silk and the fibers of cotton were spun into yarn and then woven into cloth, and it was the nimble fingers of the housewife that carried the process through from the matted raw product to the finished garment.
It is comparatively easy to comprehend the development of machines for dealing with such gross material as earth, rock, iron, and wood, but when we come to consider the infinitely delicate and almost imponderable fibers that go to make up our textiles, the marvel is that any but highly skilled human hands, guided by keen eyesight, could combine the tangled and obstreperous filaments into fine yarn and weave this yarn into complicated patterns of cloth. But the spinning wheel and hand loom could not stand long in the path of power-driven machinery, and now huge, blind machines, with stiff, unbending fingers of metal, comb out the matted masses of raw material, remove the dirt and twigs, straighten out the snarls far quicker and better than could be done by hand, and transform the fibers into beautiful fabrics such as in former days would have been the envy of kings.