July 30, 1886.] 



SCIENCE. 



101 



quently the westerly winds must be at least twice as 

 strolls' in Januarj' as in July, notwithstanding: Dr. 

 Newberry seems to think there may not be much dif- 

 ference. If the annual average velocity of wind, 

 therefore, whatever it may be, causes a difference of 

 level between America and France of 2.4 inches, then 

 this difference in January is 3.2 inches, and in July 

 only 1.6 inches, and consequently a change of differ- 

 ence of sea-level of 1.6 inches between the two 

 seasons. The discussion of long series of tide obser- 

 vations on both sides of the Atlantic gives a small 

 annual inequality of sea-level with a range of several 

 inches ; but both the ranges and the epochs of maxi- 

 mum height of sea-level are nearly the same on both 

 sides, the latter occurring in the fall ; and so there 

 can be, at most, only a very small change between 

 January and July, not possibly as much as 1.6 inches, 

 and therefore the average wind of the year cannot 

 cause a difference as great as 2.4 inches, deduced 

 from the preceding argument upon the hypothesis 

 that wind-friction is in proportion to the velocity. It 

 is admitted that some of the data upon which these 

 results are based are somewhat uncertain ; but if 

 some of them are in error, a fourth or even a third 

 part, it affects the argument very little. 



Upon the usual assumption that friction between 

 the different strata of water is proportional to the 

 relative velocities without regard to difference of 

 pressure at different depths, it is readily inferred, 

 from what precedes, that the absolute surface velo- 

 city is independent of depth of water, and so a wes- 

 terly wind of 40 miles an hour across the Atlantic 

 would give rise to the same surface velocity as on 

 Lake Erie. Dr. Newberry has not furnished us with 

 any observation of surface velocity, and therefore we 

 cannot infer what the velocity of surface water on 

 the Atlantic, corresponding, say, to the average ve- 

 locity of about 8 miles per hour, would be. This, if 

 wind-friction is proportional to the velocity, would be 

 one-fifth of that on Lake Erie corresponding to a 

 velocity of 40 miles per hour. If the wind does not 

 blow the water against a barrier, but in circuits, of 

 course the case is very different. 



In the trade-wind latitudes the westerly component 

 of motion is perhaps about the same as the easterly 

 component of the middle latitudes in the North At- 

 lantic ; and, as the tropical sea between Africa and 

 the Gulf of Mexico is much deeper, we may infer, 

 from what precedes, that the trade-winds cannot 

 possibly cause a difference of sea-level of two inches, 

 and hence raise the level of the Gulf of Mexico as 

 much as one inch above the normal undisturbed level. 

 The winds, therefore, can have no sensible influence 

 in producing the Gulf Stream, for this deep and 

 rapid current can only be caused by a difference of 

 sea-level between the Gulf and the parts in higher 

 latitudes toward which it flows. 



Wm. Fekrel. 

 Washington, July 18. 



Neff's gas-wells. 



In the geological map of Ohio, showing the posi- 

 tions of the oil and gas wells {Science, June 25, 1886), 

 there is a circle enclosing these words. ' Neff's gas- 

 wells.' This region was discovered in 1864 as geologi- 

 cally, and in many particulars physically, the dupli- 

 cate of the Venango county, Penn., region. In 1865 

 well No. 1 was bored, proving the substratification 

 of the subcarboniferous shales and sands to be the 



equivalents of those in Pennsylvania ; but. in place 

 of striking oil, there was developed a remarkable 

 gas-well, which has been described by tourists and 

 scientific men as a geyser of great violence. A full 

 account of all the wells has been published in the 

 Ohio state geological survey, and quite recently in 

 the tenth volume of the Tenth census of the 

 United States, by Prof. S. F. Peckham. 



Some of the wells discharge a few gallons of oil 

 each day, of a superior lubricating quality, gravity 



The analysis of the gas is as follows : — 



Marsh-gas 81 .4 



Ethyl hydride 12.2 



Nitrogen 4.8 



Oxygen 0.8 



Carbon monoxide 0.5 



Carbon dioxide 0.3 



100.0 



There is also a small amount of free hydrogen 

 which is carburetted before burning. 



The analysis of the carbon, known as an article of 

 commerce by the trade-mark, ' Patented diamond 

 black,' produced from the gas of these wells by 

 patented processes granted the writer, is as fol- 

 lows : — 



Carbon > 95.057 



Hydrogen! 0.665 



Nitrogen O.I^'S 



Carbon monoxide-,, 1.378 



Carbon dioxide ^ 1..3S6 



Water 0.682 



Ash (Fe„03 and UuO) O.O.'ie 



100.000 



The pressure on these wells is not the same in all. 

 There is a pressure for each well ; at which degree 

 of pressure there is an equilibrium between the gen- 

 eration or discharge of the gas, and the well's state 

 of rest or quiet. Very little salt water is found in 

 these wells, and it gives little trouble. Observations 

 show that the supply increases in warm weather and 

 in the heat of the day, and regularly with the varia- 

 tions of the moon, being strongest at the full moon. 

 The gas is a rich illuminating hydro-carbonaceous 

 gas, and, even when mixed with seven parts of 

 atmospheric air, is a good illuminant. Well No. 2 

 has been systematically examined ; and there is no 

 apparent diminution in the supply of gas, during the 

 past foui'teen years of the twenty years the well has 

 been ' blowing.' Where is it from ? 



That there is a limit to the supply of petroleum or 

 gas cannot be questioned ; but, with proper scientific 

 and economical use of wells and territory, the life of 

 a well can scarcely be measured or computed : it is 

 too great in quantity, and too long in time. 



Fresh water will ' drown out ' a well. Will not 

 holding a well under pressure until its equilibrium 

 between a state of rest and production is about 

 established, injure the well ? It is an injury ; there- 

 fore transporting gas through long lines of pipe, by an 

 initial potential force amounting to several hundred 

 pounds' pressure at the wells, is not the correct way. 

 There is a reduction of pressure of about eight 

 pounds to the mile in pipes. For long distances it 

 will be proven that gas can be blown more economi- 

 cally, and to better advantage to wells and trans- 

 portation, through the pipes, than be forced by its 



1 Including the C and H of 0.034 solid hydrocarbon. 



2 These gases were doubtless partly formed from solid 

 carbon and occluded oxygen by the heat applied in vacuo. 



