GEOLOGY. 305 



in the fresh-water limestones of Germany, prepare the geologist for the 

 occurrence of fossil reptilian eggs in the oolitic limestones, which are often 

 similar to the coral-sands of our present seas. 



Motion of Glaciers. --The results of an expedition to the Alps, in the 

 winter of 18-39, by Professor Tyndall, of London, have been published 

 during the past year. He remained two nights at Moutanvert, and deter- 

 mined with a theodolite the motion of the Mer-de-Glace, and found it to be 

 about one-half of its summer's motion. Crystals of snow fell almost with- 

 out intermission during the progress of the measurements. He afterwards 

 visited the vault of the Aveiron, and found a turbid stream issuing from it, 

 indicating that even in winter the motion of the glacier along its bed, by 

 which the rocks over which it passes are ground, is never suspended. 



PETROLEUM OR ROCK OIL WELLS. 



Considerable excitement has been occasioned during the past year by the 

 obtaining of large supplies of Petroleum, or, as it is commonly called, " Rock 

 Oil," in Northern Pennsylvania, and the application of the same to commer- 

 cial purposes. The yield of some of the wells which have been opened by 

 boring is very remarkable. At Oil Creek, Yenango County, Pennsylvania, 

 single wells are reported to have yielded from four hundred to eight hundred 

 or even one thousand gallons daily. In some instances the oil overflows from 

 the opening of the Avell spontaneously, but in most cases it is obtained by 

 pumping. The crude oil burns dimly, and is a very good lubricator, but 

 when refined it has little smoke or odor, and in illuminating qualities equals 

 the best coal-oils. Its price at the wells of Pennsylvania is about twenty 

 cents per gallon, and it is estimated that from twenty thousand to thirty thou- 

 sand barrels have been afforded by the State of Pennsylvania during the past 

 year. Near Pittsburg there are several oil wells, which yield a supply nearly 

 sufficient to employ two works in refining it. At Petroleum, on the North- 

 western Railroad of Virginia, and within a radius of ten miles around it, there 

 are thirty wells being pumped, averaging five barrels per day each, giving 

 a total of one hundred and fifty barrels per day. Boring for oil in this 

 region is constantly going on, and it is probable it will be very produc- 

 tive. On the Kanawha river, in Virginia, at the salt works, the oil has been 

 " tubed out " of the wells on account of its damaging the quality of the 

 salt, but it is believed that a large quantity could be obtained there by 

 proper boring. 



The cost of boring a well in the oil districts of Pennsylvania from two 

 to four inches in diameter varies with the locality, six hundred dollars 

 being considered sufficient for a well two hundred feet deep in some places, 

 and two hundred dollars for one of one hundred feet in depth in others. 

 For a well yielding ten or fifteen barrels per day, the outlay, to include 

 tanks in which the oil is separated from water by settling, and sheds, work- 

 shops, etc., is from $1000 to S1500. The long duration of this supply of 

 natural oil is somewhat doubtful, from the fact that a number of the wells 

 have ceased to yield; but it is certain that an immense quantity will be 

 obtained for years to come; and it is not improbable that, with a better 

 knowledge of the geology of the country, and the experience which is fast 

 accumulating, the oil wells may be made a permanent source of wealth. 



Concerning the origin of these oils, no doubt can be entertained that they 

 have exuded, or have been distilled, from animal or vegetable products, the 



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