dirt or gravel.  When the debris accumulates too thickly around the drill, the latter is drawn up rapidly.  The debris has previously been reduced to mud by keeping the drill surrounded by water.  A sand pump, not unlike an ordinary syringe, is then let down, the mud sucked up, lifted, and then the drill sent down to begin its pounding anew.  Great deftness and experience are needed to work the drill without breaking the jars or connected machinery, and, in case of accident, there are grapples, hooks, knives, and other devices without number, to be used in recovering lost drills, cutting the rope, and other emergencies, the briefest explanation of which would exceed the limits of this letter.

The exciting moment in boring a well is when a drill is penetrating the upper covering of sand rock which overlies the oil.  The force with which the compressed gas and petroleum rushes upward almost surpasses belief.  Drill, jars, and sinker bar are sometimes shot out along with debris, oil, and hissing gas.  Sometimes this gas and oil take fire, and last summer one of the wells thus ignited burned so fiercely that a number of days elapsed before the flames could be extinguished.  More often the tankage provided is insufficient, and thousands of barrels escape.  Two or three years ago, at the height of the oil production of the Bradford region, 8,000 barrels a day were thus running to waste.  But those halcyon days of Bradford have gone forever.  Although nineteen-twentieths of the wells sunk in this region “struck” oil and flowed freely, most of them now flow sluggishly or have to be “pumped” two or three times a week.

“Piping” and “casing,” terms substantially identical, and meaning the lining of the well with iron pipe several inches in the interior diameter, complete the labor of boring.  The well, if a good flowing one, does all the rest of the work itself, forcing the fluid into the local tanks, whence it is distributed into the tanks of the pipe-line companies, and is carried from them to the refineries.  The pipe lines now reach from the oil regions to the seaboard, carrying the petroleum over hill and valley, hundreds of miles to tide-water.

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A CEMENT RESERVOIR.

The annexed figures represent, on a scale of 1 to 50, a plan and vertical section of a reservoir of beton, 11 cubic meters in capacity, designed for the storage of drinking water and for collecting the overflow of a canal.  The volume of beton employed in its construction was 0.9 cubic meter per cubic meter of water to be stored.  The inner walls were covered with a layer of cement to insure of tightness.

[Illustration:  A CEMENT RESERVOIR.]

T is the inlet pipe, with a diameter of 0.08 m.

T’ is the distributing pipe, and T” is the waste pipe.—­Annales des
Travaux Publics.

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