The “swallow,” for so it is named, is made entirely of steel and wrought iron.  It is very easily kept clean; the horse can be harnessed to it in three minutes; and, aside from its uses for pleasure, it is capable of being utilized in numerous ways.—­La Nature.

[Our excellent contemporary, La Nature, is mistaken in its account of the above vehicle.  It is an American invention and was first published, with engraving, in the SCIENTIFIC AMERICAN, December 16, 1882.]

* * * * *

BORING AN OIL WELL.

HOW THE HOLE WAS MADE AND THE OIL BROUGHT UP.

A letter from Bradford, Pa., says:  The machinery used in boring one of these deep oil wells, while simple enough in itself, requires nice adjustment and skill in operating.  First comes the derrick, sixty feet high, crowned by a massive pulley.

The derrick is a most essential part of the mechanism, and its shape and height are needed in handling the long rods, piping, casting, and other fittings which have to be inserted perpendicularly.  The borer or drill used is not much different from the ordinary hand arm of the stone cutters, and the blade is exactly the same, but is of massive size, three or four inches across, about four feet long, and weighing 100 or 200 pounds.  A long solid rod, some thirty feet long, three inches in diameter, and called the “stem,” is screwed on the drill.  This stem weighs almost a ton, and its weight is the hammer relied on for driving the drill through dirt and rock.  Next come the “jars,” two long loose links of hardened iron playing along each other about a foot.

The object of the jars is to raise the drill with a shock, so as to detach it when so tightly fixed that a steady pull would break the machinery.  The upper part of the two jars is solidly welded to another long rod called the sinker bar, to the upper end of which, in turn, is attached the rope leading up to the derrick pulley, and thence to a stationary steam engine.  In boring, the stem and drill are raised a foot or two, dropped, then raised with a shock by the jars, and the operation repeated.

If I may hazard a further illustration of the internal boring machinery of the well, let the reader link loosely together the thumbs and forefingers of his two hands, then bring his forearms into a straight line.  Conceiving this line to be a perpendicular one, the point of one elbow would represent the drill blade, the adjacent forearm and hand the stem, the linked finger the jars, and the other hand and forearm the sinker bar, with the derrick cord attached at a point represented by the second elbow.  By remembering the immense and concentrated weight of the upright drill and stem, the tremendous force of even a short fall may be conceived.  The drill will bore many feet in a single day through solid rock, and a few hours sometimes suffices to force it fifty feet through