MINING AND TRANSPORTATION OF PETROLEUM. The modern method of drilling for petroleum is similar to that used in sinking gas and artesian well.. The most prominent feature of the drilling outfit is the derrick, which is a tall, pyra mid-like wooden frame about 75 feet high, 12 feet square at the base and about 3 feet at the top. The cost of a rig, as it is called, ranges from $200 to $275. The diameter of the well hole is 10 or 12 inches at the surface, decreasing with depth to 5 or 6 inches. In Russia wells are drilled of much greater diameter, and 20 inches is not an unusual size for the beginning of the bore-hole. In many cases the oil does not flow when the oil-hearing rock is struck, and it is in this instance to explode a torpedo at the bottom of the drill-hole, whereupon the oil almost immediately begins to pour out of the well sometimes with tremendous velocity. For details of petroleum sec WELL-SINKING.
The question of cheap and rapid transportation of erode petroleum from the wells to the refin eries is one of great. importance. At first the oil was transported on carts, later it was carried in barges or by railway in tank (qtrs. but these
methods gave plaeo to the systo-m of pipe hoes. At the present day the total length of pipe lines transporting Pennsylvania crude oil is probably over 25.000 miles. The pipes, which have a diam eter of from 4 to g inches, are usually laid under ground and have bends at regular intervals to allow for contraction and expansion. With pumps and storage tanks are in in 25 to 30 miles apart. the oil lx•ing received into the tank at one pumping station and then forced through the pipe to the next one. Since all petro leum contains more or less paraffin or wax. much trouble is often experienced in the clogging of the pipes, especially in cold weather, and to clear them out an instrument known as the 'go devil' is sent through the pipe. This is so eon structed that it. is tureen along by the moving current of oil and serapes the paraffin off from the inside of the tube. Pipe lines have been built from the Appal ichian oil region to .Jersey Ity, Philadelphia, Baltimore, Chicago, and Cleveland.