I will therefore pass on to deal briefly with the Russian free-fall system so much in vogue in the Russian fields. Incidentally, I may here say that when drilling for oil in Russia, one has to recollect several features which are not common to the development of other oil-fields. Bearing in mind the great depth to which wells have to be sunk to reach the prolific oil horizons in the majority of the fields in Russia, which necessitates starting the well with a very large diameter--frequently 30 inches--it will be easily appreciated that the loss of a hole in the course of drilling is a very expensive affair. The Russian free-fall system of boring necessitates patient and hard manual labour. It is, as its name implies, of the percussion type, and is, in fact, a modified pole-tool system which well suits the local conditions. The clumsy drilling tools have a practically free drop, being picked up when the walking beam is at its lowest point, and released at the top of the stroke. When released, the tools naturally force their way downwards in the strata, and are released only with difficulty, although in a measure this difficulty is minimized on account of the fact that the under-reaming (slightly enlarging the diameter of the hole) is done simultaneously with the drilling. After a Russian well has been started by means of a slip-hook suspended from a haulage rope, and a depth of some 30 feet obtained, the free-fall is added to the string of tools. This free-fall is composed of two separate parts--the rod and the body--and these are held together by means of a wedge working in vertical slots cut in the sides of the body. In operating the free-fall, the handles, fixed to the temper screw, are held by the driller. On the downward stroke these are pushed forward from right to left, but as soon as the downward stroke is completed, they are quickly pulled backwards. The steel wedge enters the recess and the tools are carried to the top of the stroke, where, by a quick forward jerk, the wedge is thrown clear of the recess, and the tools drop freely, the momentum of the string of tools driving the drilling bit deeper into the hole. After several feet of the hole are drilled, the tools have to be withdrawn in order to allow the pulverized mass of debris to be cleared away, while, owing to the caving nature of the strata, it is necessary to case the well as drilling proceeds. As I have said, the system is very cumbersome, but, in the hands of experienced men, it does its work well, if but slowly. There are many cases on record where, when the well has assumed a considerable depth, it has been completely spoiled by the carelessness of the operators, but, more often than not, this has been deliberate, for the Caucasian oil-field worker has many grievances, admittedly more or less imaginary. [Illustration: ILLUSTRATION OF THE “OILWELL” HEAVY ROTARY OUTFIT, SHOWING RING AND WEDGE (ON LEFT-HAND SIDE OF FOREGROUND) TO GRIP THE CASING]