1887.] NEW TOKK ACADEMY OF SCIEKCES. 83 



The specimens discharged into the tub are collected and pre- 

 served, and thus a complete section of the strata may be obtained. 

 The tubes may be extended by adding sections at the top as the 

 boring extends downwards. Fig. 3 shows the section obtained 

 near one of the plants on Long Island to the depth of 433 feet. 

 Two of the gravel deposits passed through were composed of 

 coarse rounded gravel, almost wholly free from any admixture 

 of fine sand or clav, an evidence that there is a continued flow 

 of water among the particles of gravel. 



Mr. Henry E. Knox, Jr., formerly a student in the School of 

 Mines, has been for many years engaged under the direction of 

 the Messrs. Andrews in prospecting for water in various places, 

 and I am indebted to him for the description of the prospecting 

 device just described. 



Mr. Knox found, between Albany and Troy, an extensive bed 

 of gravel beneath a bed of fine clay, from 16 to 25 feet thick 

 near the surface. The gravel bed is from 17 to 35 feet thick, 

 about 700 feet wide and of indefinite length, it having been 

 traced about half a mile longitudinally. 



The gravel from this bed is entirely different from that on 

 Long Island. It is composed of coarser grains or fragments of 

 dark-colored rock, nearly all of uniform size, and less rounded 

 than those from Long Island, showing evidence of that kind of 

 attrition which comes from running water rather than wave 

 action. 



Mr. Knox found precisely the same gravel in his explorations 

 near Utica ; and under a bed of clay, 118 feet thick, near Al- 

 bany, he found a bed of clean gravel, of nearly uniform size and 

 uniform material, but composed of angular, water-worn pebbles 

 as large as pigeons^ eggs. 



One of the most important questions connected with the 

 system adopted on Long Island, and which has been repeated 

 elsewhere on a smaller scale, was the permanency of the full 

 supplying capacity of the wells. 



It was urged by some distinguished engineers that the tubes 

 must tap sheets or reservoirs of still water, and that a continued 

 draught upon the system must speedily exhaust the reservoirs. 



Experience has not confirmed this view. Mr. Knox informs 



