In the oil-well boring of Pennsylvania, the rope (with about 50 feet of iron bar, sliding jaws, sinking bar, flat drill and sand pump attached) are exclusively preferred.
PRACTICAL EXAMPLES OF WELLS AS SOURCES OF SUPPLY ONLY.
Where the surface soil and underlying drift possess sufficient porous qualities for absorption of a large portion of the rain-fall, together with the natural benefits of the impervious stratum beneath, having a proper axis of inclination favorable for conducting the infiltration of adjoining water-sheds, a large supply of water may be secured by the construction of dug wells for intercepting the subterraneous water.
Fanning has computed the following available quantities, under favorable circumstances, for percolation, from one square mile of porous gathering area (the mean annual rain being assumed at forty inches depth).
| MONTH. | RATIO OF 1-12 OF | VOLUME OF PERCOLATION | NO. OF PERSONS IT |
| MEAN ANNUAL RAIN. | IN DRY YEARS. | WOULD SUPPLY AT FIVE | |
| INCHES. | CUBIC FEET. | CUBIC FEET DAILY. | |
| January, | .737 | 1,712,198 | 11,264 |
| February, | .796 | 1,479,878 | 9,736 |
| March, | 1.070 | 2,237,242 | 14,719 |
| April, | .814 | 566,861 | 3,729 |
| May, | 1.462 | 387,974 | 2,552 |
| June, | .964 | 88,282 | 581 |
| July, | 1.077 | 51,110 | 336 |
| August, | 1.251 | 30,202 | 199 |
| September, | 1.015 | 46,464 | 305 |
| October, | 1.076 | 989,976 | 6,572 |
| November, | .937 | 2,176,838 | 14,321 |
| December, | .801 | 2,604,307 | 17,133 |
The city of Brooklyn gathers its supply by intercepting ponds. The source is the southern slope of Long Island, with a drainage area of 60.25 square miles. The plain is composed of fine sand, which is saturated with excellent water, the surface of which rises twelve feet per mile from the tide level at the shore, and which appears at the surface of the ground in springs and streams, where depressions occur in the ground level. The minimum observed flow occurred in 1880, and was equal to 9.4 inches on the water-shed. The available supply is, at times, quite small.
The city of Lynn uses a driven well partly, of which they say, in their annual report for 1880:
“The doubtful character of any underground supply of water, especially when it is drawn from beneath a territory occupied by a densely settled community, makes frequent examination of its quality a duty not to be disregarded. We invite attention, however, to the fact that the chemical examination of the well water has shown an increasing quantity of foreign matter mingling with it as pumping proceeded, and that this increase suggests an inflow of water to the wells from some other source than that from which it was at first drawn.”
This method of securing water, however, is largely resorted to in the origin of water-works for small cities.