PETROLEUM 547 



great yields been kept up for more than a few months : the maximum yield at the 

 date alluded to appears to have been about 325 barrels. The MacKinley well, in 

 the same locality, is noticeable on account of its uniformity of yield, amounting to 

 between 50 and 60 barrels per diem, which production has been steadily maintained 

 without pumping for nearly 3 years. 



The uppermost Devonian or Catskill group has as yet given rise to no wells of 

 any importance. The subcarboniferous or mountain limestone, and the lower car- 

 boniferous rocks of the United States are devoid of petroleum ; but in England, traces 

 of the presence of bitumen are found in the mountain limestone in Shropshire, at 

 Castleton in Derbyshire, and at Staunton Harold in Leicestershire. In the lower coal- 

 measures, oil-wells are found in Ohio and Virginia, and also in the upper coal-measures 

 at Marietta, in the former state. A spring of actual petroleum was discovered some 

 years ago in the coal-measures at Alfreton in Derbyshire ; and while the supply 

 lasted, it was employed in the manufacture of paraffin and lubricating oils. 



In the secondary rocks, solid and liquid bitumen occur at many different points, 

 but not in the extraordinary quantities that characterise the palaeozoic rocks of 

 America ; among other localities may be mentioned Deestadt and Sickle, in Bruns- 

 wick, where it occurs in the lias shales ; and Edimissen and Odensee, in Hanover, 

 where springs of petroleum rise from the middle beds of the Wealden series, which 

 are also coal-bearing. In England, the lias jet-rock of Whitby, and the Kimmeridge 

 shale of Dorsetshire, are examples of bituminous rocks belonging to the secondary 

 period. The petroleum of California is derived from rocks of cretaceous, or perhaps 

 tertiary age. 



One of the most interesting of the tertiary petroleum districts is that of Galicia, 

 on the northern slope of the Carpathians. This, according to Von Hochstetter, ex- 

 tends N.W. S.E. for about 200 miles, along a line of fractures parallel to the main 

 chain of mountains, through which fractures petroleum rises on account of the 

 gaseous pressure below, and saturates the overlying brecciated rocks and sandstones, 

 which are of eocene age. The w.ells actually sunk are square shafts, which often 

 pass through a peculiar, breccia of fragments of bituminous shale, angular pieces of 

 asphalt, quartz grains, and flakes of mica, cemented by calc-spar. . The rock generally 

 is a sandy shale. In one of, these weUs, at 2 fathoms, deep, the cracks of the rock 

 were found to bo filled with a white bitumen like Hatchettine, and in the third fathom 

 petroleum appeared in drops, which filtered through the walls, and collected at the 

 bottom of the shaft. The oil is so full of paraffin, that it is only when a certair 

 quantity of water issues with it out of the rock, that any quantity is collected. 

 Samples collected from five different localities varied in specific gravity from 0'803 

 to 0'920, the latter being surface-oils collected from a pool of water. The lighter 

 varieties contain so much paraffin- as to solidify at a temperature of 50 F. The 

 relation between the Weet Galiciaa oil, rising from eocene rocks, to that of Eastern 

 Galicia, which is obtained from miocene strata, is similar to that existing between 

 the Pennsylvanian and Canadian oils the latter in either case being dark in colour, 

 and less fluid than the former. The Wallachian oil is also dark coloured, and is 

 associated with ozokerite or paraffin, in a similar manner to that of Galicia. Another 

 and better-known deposit of petroleum in tertiary strata is that in the Island of 

 Trinidad, which has been described at considerable length by Mr. G. P. Wall, in 

 his ' Report on the Geology of Trinidad.' 



The methods employed in America for boring oil-wells are usually of a very simple 

 character, and do not differ very much from those 'used in this country for trial- 

 borings in the coal-measures. As a rule, a rope is used for suspending the boring- 

 bar, instead of rigid rods ; the lower parts of the arrangement, known as the augur- 

 bar and sinker-bar, weigh from 7 to 9 cwts., and are united by a simple gliding 

 piece, called the 'jars,' which is, in fact, an application of the free-falling cutter used 

 in deep borings in Europe. The detritus is removed by the shell- or sand-pump, in 

 the ordinary way. A modification of Fauvelle's system, having hollow rods with 

 a continuous discharge of the detritus, was at one time in use at Oil Springs, 

 Canada West. The boring-bit has a hollow stem, the cutting edges being formed by 

 throe stout radiating pieces of steel. In the angle formed by these pieces, and their 

 junction with the stem-brass, valves are inserted which allow the detritus to enter 

 the rod through which it rises, and is discharged in jets nt every fall of the cutter. 

 The lifting of the borer is effected by toothed levers, similar to those of a safety-catch 

 used in collieries, which fall together by their own weight, and take hold of the rod 

 at the end of the stroke ; and are released by tappets attached to the boring-frame or 

 derrick, striking against their outer ends when the rod is at the top of its stroke. 

 The boring is usually performed by steam-power, the upper end of the rope being 

 secured to the outer arm of a vibrating or ' walking ' beam, receiving motion by 



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