564 



SCIENCE. 



[Vol. VII., No. 177 



In the vicinity of Macksburg, north of Marietta, 

 the light south-eastward dip of the strata is found 

 to be interrupted, and for nearly a mile a terrace- 

 like structure prevails. This is masked, it is true, 

 by the immense erosion which the country has 

 suffered, and only comes into view when the best- 

 known elements of the exposed section as coal- 

 seams are followed by means of the level. All of 

 the strata ever reached by the drill, as well as all 

 that are above the surface, are equally affected by 

 this structural irregularity. 



But this terrace is an oil-field, and has been for 

 twenty years. Oil was first found here in shallow 

 wells, from two hundred to three hundred feet 

 deep in the upper Mahoning sandstone. But ad- 

 \ enturous drillers, one after another, struck new 

 sources of oil. A second oil-sand, and a third, were 

 discovered at five hundred and seven hundred feet 

 respectively. Finally the drill was sunk deeper 

 still, until, at thirteen hundred feet, the Berea grit 

 was found, holding a stock of oil large enough to 

 make the Macksburg field for the first time a fac- 

 tor in the general market. It has produced as 

 many as three thousand barrels per day since then, 

 and is now yielding twenty-five hundred barrels 

 per day. 



But the shallow and the deep productive wells 

 are alike definitely limited to the terrace that has 

 been described. In other words, four oil-sand- 

 stones become productive in the same area when 

 the structure is found favorable. That they do 

 not communicate with each other is evident from 

 the fact that the oils which they severally contain 

 differ from each other in gravity, in color, and in 

 chemical constitution. 



The depth of the Berea grit below sea-level in 

 the terrace is 735 feet. Of twenty-four wells, oc- 

 cupying four square miles in this field, sixteen 

 reach the Berea between 733 and 737 feet, and six 

 are found by their records to be exactly 735 feet. 



On the north-western margin of the terrace, at 

 elevations of 728, 720, 713, and 704 feet, gas is 

 found, but no oil. After many hundred wells have 

 been drilled on all sides, the terrace which has 

 been revealed by the engineers level is alone found 

 productive. 



The grain of the sandstone is in every way as 

 promising, and its thickness as great, outside of 

 the field as within it ; and the sections both above 

 and a thousand feet below the Berea grit appear 

 identical in productive and in barren territory 

 alike. It is hard to resist the conclusion that the 

 Macksburg oil-field is dependent upon the struc- 

 tural irregularity here described, the other ele- 

 ments, of course, being presupposed. 



May not a like explanation be applied to the oil 

 and gas fields of Pennsylvania and New York as 



well ? Is it not possible that their productive areas 

 are also dependent on structural disturbance, slight 

 though it may be ? These areas have been some- 

 times explained as resulting mainly from the 

 coarseness of grain of the oil-sands. Lenticular 

 deposits of gravel have been suggested, arranged 

 in north-east and south-west lines for the several 

 petroliferous horizons. It is hard to see how any 

 one of these long tongues of gravel could be ac- 

 counted for, laid down so far from the shore of 

 the sea in which it was deposited. It is much 

 harder to understand how, as the geological ages 

 went by, one after another of these peculiar de- 

 posits should be laid down on these self-same lines. 

 It is certainly much easier to conceive of the oil- 

 sands as wide-spread sheets of sand and gravel, 

 that become the reservoirs of oil and gas when 

 lifted into elementary folds. This is certainly true 

 of the Berea grit in Ohio, and this great stratum, 

 it is now definitely settled, constitutes one of the 

 main oil-sands of Pennsylvania. Under this view, 

 the arrangement of the several oil-fields in north- 

 east and south-west lines becomes easily intelli- 

 gible. These oil-fields are simply conforming to, 

 as they are determined by, the main structure- 

 lines of western Pennsylvania. 



Edward Orton. 



THE HEALTH OF NEW YORK DURING 

 21 AY. 



The population of the city of New York on 

 May 1 was estimated at 1,432,094. Assuming the 

 normal increase to be 799 each week, there would 

 be, June 1, a population of about 1,435/290. Of 

 this number, 2,759 died during the month of May, 

 a mortality less by 206 than occurred during the 

 preceding month. Of children under five years 

 of age, there was a saving of 110 lives as com- 

 pared with April. The greatest mortality from 

 all causes which occurred during any one day was 

 on the 20th, when 107 persons died. Of this num- 

 ber, 24 were children under one year of age, 29 

 under two years, and 34 under five years. Con- 

 sumption caused more deaths on that day, as in- 

 deed it usually does on most days of the year, 

 than any other single disease, its victims being 

 24. The deaths during the month from diarrhoea] 

 diseases were 73, an increase of 16 over the month 

 of April. Diphtheria also caused a considerable 

 increase, its deaths t>eing 165 against 124. Scarlett 

 fever maintained the same position among the 

 mortality-factors which it had occupied for the 

 two preceding months : the deaths from this dis- 

 ease in March were 42 j in April, 49; and in May. 

 44. 



It will be remembered that while rain fell on 



