19J8] 



on The Romance of Petroleum 



341 



pump. The next slide (Fig. 8) gives a view of the interior of the 

 lower part of the derrick during drilling operations. The photograph 

 shows the drilling appliances withdrawn from the well, in order that 

 the sand-pump may be introduced. 



To exclude water, met with in upper strata, from the well, and 

 to prevent caving, the well is lined with steel artesian tubing, and, 

 as it is usually necessary to reduce the diameter as the boring pro- 

 ceeds, the well may contain several concentric strings of such tubing. 



The drilling of petroleum wells has been brought to such perfec- 

 tion that depths of a mile or more may be reached without serious 

 difficulty in a moderate length of time, l:)ut the yield of oil needs to 

 be considerable to render drilling to such depths a profitable under- 

 taking. Four years ago there were in the Boryslaw-Tustanowice 

 oil-field of Galicia sixteen wells of a depth of over 5000 feet, and one 



Fig. 3. — Interior of Derrick. 



was then yielding oil from strata which had been reached at 5873 feet, 

 or nearly a mile and a furlong. 



Drilling operations in the tropical jungle are attended with 

 exceptional difficulti< s of transport. The next two photographs 

 (Fig. 4) are of scenes in the Digboi oil-field of Assam. It will be 

 observed that the patient and intelligent elephant is here employed 

 as a labourer, and that the derricks are thatched to protect the 

 drillers from the sun's rays. 



Within recent years, the rotary system of drilling, in which a 

 rapidly-revolving annular cutter, of the type indicated by the example 

 on the lecture-table, is employed, has l)een largely adopted, with 

 great saving of time when the formation is suitable for its use. 



It not infrequently happens that oil is met with on completion of 



the well under such high pressure, sometimes several hundred pounds 



on the square inch, that the flow is uncontrollable. Most of us have 



seen pictorial representations of the famous oil-fountains of Baku, 



Vol. XXII. (Xo. 112) 2 a 



