June 26, 1885.] 



SCIENCE. 



521 



insect is now abundant in Washington, it will 

 scarcely be noticed in any part of the District 

 seventeen years hence. I base this opinion 

 upon a new phase in the cicada historj- ; viz., 

 the presence of the English sparrow. It is the 

 first time, perhaps, in the history of the world, 

 that Passer domesticus has had an opportunity 

 of feeding upon this particular brood of Cicada 

 septendecim : and so ravenously and persist- 

 ently does this bird pursue its food, that the 

 ground is strewn with the wings of the unfor- 

 tunate cicada wherever these have been at all 

 numerous ; so that, considering the numbers 

 of the sparrow and their voracity, very few of 

 the cicada will be left long enough to procreate 

 and perpetuate the species in this District. 



* * * * * 



THE GEOLOGY OF NATURAL GAS. 



The recent introduction of natural gas into 

 general use as a source of heat for industrial 

 and domestic purposes has raised it from the 

 rank of a mere curiosity to one of the earth's 

 most valuable treasures. 



To the reader unacquainted with the great 

 change natural gas has effected in all indus- 

 tries where it can be obtained, the following 

 quotation from an article in Macmillan's mag- 

 azine for January, written by Mr. Andrew 

 Carnegie, the chief iron master of Pittsburgh, 

 will be a revelation: "In the manufacture 

 of glass, of which there is an immense quan- 

 tity made in Pittsburgh, I am informed that gas 

 is worth much more than the cost of coal and 

 its handling, because it improves the qualit} 7 

 of the product. One firm in Pittsburgh is al- 

 ready making plate glass of the largest sizes, 

 equal to the best imported French glass, and is 

 enabled to do so by this fuel. In the manu- 

 facture of iron, and especially in that of steel, 

 the quality is also improved by the pure new 

 fuel. In our steel-rail mills we have not used 

 a pound of coal for more than a year, nor in 

 our iron mills for nearly the same period. The 

 change is a startling one. Where we formerly 

 had ninety firemen at work in one boiler-house, 

 and were using four hundred tons of coal per 

 day, a visitor now walks along the long row of 

 boilers, and sees but one man in attendance. 

 The house being whitewashed, not a sign of the 

 dirt}- fuel of former days is to be seen ; nor do 

 the stacks emit smoke. In the Union iron- 

 mills our puddlers have whitewashed the coal- 

 bunkers belonging to their furnaces. Most of 

 the principal iron and glass establishments in 

 the city are to-day either using this gas as fuel, 

 or making preparations to do so. The cost 



of coal is not only saved, but the great cost 

 of firing and handling it ; while the repairs to 

 boilers and grate-bars are much less." 



This new fuel, which bids fair to replace coal 

 almost entirely in many of our chief industrial 

 centres, has not received that attention from 

 the geologist which its importance demands. 

 So far as the writer is aware, nothing has been 

 published on the subject which would prove of 

 any value to those engaged in prospecting for 

 natural gas, and it is the existence of this 

 blank in geological literature that has sug- 

 gested the present article. 



Practically all the large gas-wells struck 

 before 1882 were accidentally discovered in 

 boring for oil ; but, when the great value of 

 natural gas as fuel became generally recognized, 

 an eager search began for it at Pittsburgh, 

 Wheeling, and many other manufacturing cen- 

 tres. 



The first explorers assumed that gas could 

 be obtained at one point as well as another, 

 provided the earth be penetrated to a depth 

 sufficiently great ; and it has required the ex- 

 penditure of several hundred thousand dollars 

 in useless drilling to convince capitalists of this 

 fallacy which even yet obtains general credence 

 among those not interested in successful gas 

 companies. 



The writer's study of this subject began in 

 June, 1883, when he was employed by Pitts- 

 burgh parties to make a general investigation 

 of the natural-gas question, with the special 

 object of determining whether or not it was 

 possible to predict the presence or absence of 

 gas from geological structure. In the prosecu- 

 tion of this work, I was aided b} 7 a suggestion 

 from Mr. William A. Earsenian of Allegheny, 

 Penn., an oil-operator of man} 7 3 T ears' expe- 

 rience, who had noticed that the principal gas- 

 wells then known in western Pennsylvania were 

 situated close to where anticlinal axes were 

 drawn on the geological maps. From this he 

 inferred there must be some connection between 

 the gas-wells and the anticlines. After visiting 

 all the great gas- wells that had been struck in 

 western Pennsylvania and West Virginia, and 

 carefully examining the geological surround- 

 ings of each, I found that every one of them 

 was situated either directly on, or near, the 

 crown of an anticlinal axis, while wells that 

 had been bored in the synclines on either side 

 furnished little or no gas, but in many cases 

 large quantities of salt water. Further obser- 

 vation showed that the gas-wells were confined 

 to a narrow belt, only one-fourth to one mile 

 wide, along the crests of the anticlinal folds. 

 These facts seemed to connect gas territory 



