AND "VOLCANIC BOMBS." 2?5 



quite incapable of competing with us at home on equal terms that 

 is, when both have to obtain the oil as a manufactured product of 

 artificial distillation. 



If anything like moderation were possible in America, the first in- 

 dications of scarcity would be followed by some economy in work- 

 ing ; but this is not to be anticipated. It is more likely that the first 

 rise of prices will attract additional speculation, and the sinking of 

 more wells in the hope of large profits, and this of course will shorten 

 the period of gradual exhaustion, the commencement of which may, 

 for aught we know, be very near at hand, especially if the new pro- 

 jects for using petroleum as furnace-fuel under steam boilers, and for 

 the smelting, puddling, and founding of iron and other metals, are 

 carried out, as they may be so easily at present prices, and with the 

 aid of pipe-lines to carry the crude or refined oil from the wells to 

 any part of the great American continent where it may be required in 

 large quantities. 



The old story of the goose that laid the golden eggs seems to be in 

 course of repetition in Transatlantic Petrolia. 



Since the above was written I have received from Dr. Sterry Hunt 

 a copy of his interesting " Chemical and Geological Essays," in one 

 of which he expounds a theory of the origin of petroleum. He states 

 that it appears to him " that the petroleum, or rather the materials 

 from which it has been formed, existed in the limestone rocks from 

 the time of their first deposition," and " that petroleum and similar 

 bitumens have resulted from a peculiar transformation of vegetable 

 matters, or in some cases of animal tissues analogous to these in 

 composition." 



The objections on page 299 apply to the animal tissues of this 

 theory, and as regards the vegetable matter I think it fails from the 

 want of anything like an adequate supply in these limestone rocks. 



CHAPTER XXXIX. 



ON THE SO-CALLED " CRATER NECKS" AND "VOLCANIC BOMBS*' OF 

 IRELAND. 



A Paper Read at the Geologists' Association, December 6th, 1878. 



MR. HULL, " Physical Geography and Geology of Ireland," p. 68, 

 under the head of " Volcanic Necks and Basaltic Dykes," says that 

 " although the actual craters and cones of eruption have been swept 

 from the surface of the country by the ruthless hand of time, yet the 

 old ' necks,' by which the volcanic mouths were connected with the 

 sources of eruption can occasionally be recognized ; they sometimes 

 appear as masses of hard trap, columnar or otherwise, projecting in 

 knolls or hills above the upper surface of the sheets through which 

 they pierce." 



In other cases, the " neck" consists of a great pipe choked up by 

 bombs and blocks of trap, more or less consolidated, bombs which 



