DETAILED STUDY OF SECTIONS 



171 



2"<*Ave. 



Line 



in level are, however, revealed by the indi- 

 vidual borings. To bring out in some meas- 

 ure these differences in the profiles along the 

 northern and southern margins of the belt it 

 is only necessary to study the individual 

 sections. 



Tiventy- sixth Street and Third Street reefs. — 



The first mentioned of these is located in the b 



B 



channel of East river off the foot of Twenty- J 



sixth street, New York, at about one-third * 



the distance to the Brooklyn shore. The *§ 



Third Street reef is in mid-channel opposite £ 



the foot of Third street. From information g 



received from Captain Jadwin, of the Corps g. 



of Engineers, United States Army, both reefs 2. 



are of gneiss. g" s 



East River bridge number 2 {Williamsburg <? ' 



bridge).— This bridge, now approaching com- | • 



pletion, connects Delancy street, Manhattan, J \ 



with the space between the South Fifth Street 5' I 



and South Sixth Street piers, Queens. For ? ! 



the New York tower, anchorage, and ap- ►< « 



proach, and for the Williamsburg tower, a R- j 



large number of drill holes were sunk, those g. \ 



under the towers and anchorages with core £ : 



drills. The rock, so far as encountered, is « 



everywhere gneiss and the surface much | 



more regular than in most other sections. a 



Figure 17 is made from the extensive draw- -• 



ings kindly furnished by Mr H. A. La § 



Chicotte, of the New York department of £ 



bridges. Through the courtesy of Mr R. S. | 



Buck, the former chief engineer, the writer ? 

 was permitted to examine the cores from the 

 foundations of the towers and anchorages. 



East River bridge number S. — Diamond drill 

 borings were put down at a number of points 

 under each of the piers and anchorages of 

 this bridge, and carried about 10 feet into 

 the rock in every case. Through the cour- 

 tesy of Mr R. S. Buck, chief engineer, the cores from all these borings 

 were opened up for the writer's inspection. In all cases but one the 



Bulkhead. 



LTrie 



Vernon Ave.. 



