During recent years, the rotary method of drilling has been successfully adopted, and it is in regard to this revolutionary method of speedy drilling that I will now touch upon. The rotary method of drilling made its début in Texas some fourteen years ago, and since then it is not any exaggeration to say that nearly 20,000 wells for oil have been drilled with the system, which has found popularity in all the oil-fields of the world. Its main operation is simplicity itself: a rigid stem of heavy pipe rotates a fish-tail drilling bit at the bottom of the hole, cutting and stirring up the formation to be drilled. It cuts its way through the underground formations, much in the same way as a screw when rotated forces its way through wood. It is the essence of speed in drilling, for, unlike the necessary principles to be adopted in the percussion methods of drilling, the rotary drill does not have to be lifted from the hole for the purposes of clearing. The pulverized strata are continuously washed from the hole by a stream of water reaching the bottom of the drill. Very frequently, a pressure-fed mud is used, and this serves a double purpose, for in its return to the surface it tends to plaster the walls of the well. The mud emerges in streams of high velocity from the two apertures in the drilling bit (for in its downward course it is carried through the drilling pipe or stem), but naturally loses this velocity considerably in its return to the surface. It is, however, very easy to detect the kind of stratum being drilled through from the returned cuttings, these reaching the surface but a few minutes after the drilling bit has entered the formation. From time to time various grievances have been ventilated against this improved system of boring for petroleum, but to-day its adoption is world-wide, and by its use wells which, with the old-fashioned method of drilling would take many months if not two or three years, are now got down to the producing horizons in but a few weeks. It is, in fact, solely due to the ever-increasing use of the rotary drill that the universally increased demands for petroleum products have been met by an ever-increasing production of the crude oil.