the influx of oil would be injured, and had to be occasionally cleansed from the accumulation of mud. In the twenties, the daily yield of the separate cisterns varied between 8 and 140 pud, but according to Abich's statement, 70 pits at Balakhani produced in 1856, 250,000 pud. When the news of Drake's success penetrated to the Caucasus, Colonel Norvosiljoff caused borings to be made in the Kubany district near Kudako. The experiment showed such good results that Mirsojeff, a rich Armenian, who rented the crown pits in the Apscheron peninsula, also made drilling experiments, the success of which forms the basis of the present large Russian petroleum industry.

Artesian Wells.

In the petroleum industry artesian wells form the transition to the present deep borings. Although they have not been especially employed for obtaining oil, their use is as old as the primitive methods previously mentioned. In China the Jesuit missionaries found artesian wells in full operation. These wells were drilled for brine and natural gas, the latter being frequently accompanied by petroleum. It may be interesting to give an extract from Abbe Huc's work on China, describing the Chinese method of drilling wells:

"The wells are usually from 1500 to 1800 feet deep, and only 5 or 6 inches in diameter. The mode of proceeding is as follows: If there be a depth of 3 or 4 feet of soil on the surface, they plant in this a tube of wood surmounted by a stone, in which an orifice of the desired size of 4 or 5 inches has been cut. Upon this they bring to work in the tube a rammer of 300 or 400 pounds weight, which is notched and made a little concave above and convex below. A strong man, very lightly dressed, then mounts a scaffolding, and dances all the morning on a kind of lever that raises this rammer about 2 feet and then lets it fall by its own weight. From time to time a few pails of water are thrown into the hole, to soften the material of the rock and reduce it to pulp. The rammer is suspended to a rattan cord not thicker than your finger, but as strong as our

ropes of catgut. This cord is fixed to the lever, and a triangular piece of wood is attached to it, by which another man, sitting near, gives it a half turn, so as to make the rammer fall in another direction. At noon this man mounts on the scaffold and relieves his comrade till the evening, and at night these two are replaced by another pair of workmen. When they have bored 3 inches they draw up the tube, with all the matter it is loaded with, by means of a great cylinder which serves to roll the cord on. In this manner these little wells or tubes are made quite perpendicular and as polished as glass. rock is good the work advances at the rate of two hours, so that about 3 years are required to dig a well.”1 In Europe the first artesian well was drilled in 1126, at Lillers, in the department Pas de Calais, France. However, on a more extensive scale, artesian wells appear to have first been drilled in Modena and in Austria. The term artesian well is derived from the county Artois, the soil of which is especially suitable for drilling such wells.

When the feet in 24

In the United States the first artesian well was drilled in 1809, and furnished, besides a very large volume of gases, a great quantity of oil. Prior to 1858, a great many wells had been drilled for brine in the valley of the Ohio and its tributaries, with such additional improvements as rendered them very effective for this purpose. Steam, horse and hand power had been employed in drilling with equal success, the tools and general manipulations of the well being essentially the same. The drilling of wells with hand-power was accomplished by means of a spring-pole. For this purpose a straight tree, 40 or 50 feet in length, was selected. After the branches were removed, the butt was secured in the ground in such a position that the pole extended at an angle of about 30°over the spot at which the well was to be bored. To the smaller end the tools were attached, and by the elasticity of the pole, as it was alternately pulled down and allowed to spring back, they were lifted and made to strike at the bottom of the well.2

'Travels in the Chinese Empire, 1300. Harper's ed., 1855. 2 S. F. Peckham, Report on Petroleum.'

The success which attended the drilling of artesian wells gave, indirectly, rise to the drill. The drilling of the first petroleum well by Colonel Drake has already been described.

Drilling for Petroleum.

Prior to drilling it is absolutely necessary to acquire as thorough a knowledge as possible of the geology of the soil, in order to determine, on the one hand, the point where to sink the drill, and, on the other, to what depth drilling might have to be done to attain the desired result. These two factors serve as the basis for the choice of one or the other of the customary drilling systems, it not being the same whether by a drilling system chosen at will a slighter or greater depth is to be attained in a soft, for instance, a slimy or sandy soil. A drill which may be very suitable for a soft soil and a slight depth would perform but poor work in drilling through a hard soil and to a greater depth. The principal drilling systems in use are the rotatory, percussive and free-fall systems. There is more or less difference in the drilling and auxiliary tools, as well as in the execution of the drilling operation itself.

I. DRILLING TOOLS.

A. For the Rotatory Method.

The screw auger, Fig. 7, is used for slight depths; the diameter does not exceed 4 inches, while the diameter of the stem should be at least I inch.

The common earth or clay auger, Fig. 8, may be used for slight depths and for penetrating soft rock, clay and sand. A stout stem is required.

The drill with diamond or steel crown consists of a hollow rod through which a continuous supply of water is forced down to keep the crown cool and to carry off the debris formed by the erosion of the strata by the crown. The water flows through channels cut in the face of the crown, rises on the out

side of the core-tube to the surface, and is collected in settling ponds where the sediment is deposited. For soft rock steel crowns are used, while for harder rock the crown is provided with black diamonds (Fig. 9.).

FIG. 7.

FIG. 8.

FIG. 9.

The method of cutting hard rocks employed by the ancient Egyptians remained a mystery for a long time. However, a solution of this question seems to have been found by the researches of Flinders,' who through various finds at Gizeh came to the conclusion that the Egyptians used precious-stone drills. He states that granite broken from a drill-hole at Gizeh showed marks which can be explained only by the use of solid points of precious stones. Hence the diamond drill can no longer be considered a modern tool, and Fauck's statement that it was employed in the stone and bronze ages seems plausible.

For deep drilling the diamond drill was first employed in the United States, but it was improved by Captain Beaumont, an Englishman. However, this improvement embraces only the

i Flinders, "The Pyramids and Temples of Gizeh."

machinery of the drilling operation, the drill itself remaining essentially the same as employed for a long time by Leschot in Switzerland. The boring rods are tubes of drawn steel, 2 inches outside diameter and 3/8 inch in thickness, in lengths of 5 feet. To the lower end of the rods is screwed the core-tube, 15 feet long, the diameter of which corresponds to that of the drill-hole (21⁄2 to 3 inches). The drilling crown is screwed to the core-tube and contains eight or more black diamonds. Only a small portion of the diamonds projects above the edge of the crown in which they are imbedded, otherwise they might readily break out. Fig. 9 shows the arrangement of the diamonds, as well as the channels between them for the passage of the rinsing water and for carrying away the debris.

By utilizing the inventions of Koebrich, Olaf Terp and others, the Well Works Co. of Aurora, Ill., has succeeded in arranging the boring machinery so that the drill alternately exerts a rotatory and percussive effect. The advantage of this invention consists in the use of a feed-cylinder, Fig. 10, suspended to the stirrup a, which for drilling with the use of water serves for regulating the feed for the hollow stem. The water enters at c and is discharged at b, or with the valve closed, by lifting the piston d, through the apertures f.

FIG. 10.

The great cost of the diamond drill has thus far been a hindrance to its general introduction, though in some cases it cannot be employed on account of local conditions. However, by comparing the rapidity and quantity of effect of a diamond drill with that of a free-fall drill worked by steam

power, it will readily be seen that the cost of the former is completely compensated by its advantages. Thus the average daily performance of a free-fall drill with steampower is about 5 feet, and if a hole 1800 feet deep has to be drilled, 360 working days would be required for the purpose. The average performance of a diamond drill is about 30 feet per day, so that for a depth of 1800 feet only 60 working days