16 Observations on the increase of Sandy Hook. 
Art. III.— Observations to determine the cause of the increase of 
Sandy Hook, made by the Coast Survey for the Commissioners on 
Harbor encroachments of New York ; by Prof. A. D. BacHE, 
Sup. U.S. Coast Survey.—(Abstract.) 
It is known as one of the developments of the Coast Survey 
that the peninsula of Sandy Hook is gradually increasing, grow- 
ing to the northward into the main ship channel. A spot north 
ot the Hook where there was-forty feet of water when Captain 
Gedney made his survey, in less than ten years was nearly bare 
at low water. The importance of determining the cause of this 
increase, as leading to the means of controlling it, cannot be over- 
estimated. The Commissioners on Harbor Encroachments had 
early attended to this matter, and requested that the necessary 
observations for its investigation should be made. These were 
made under my immediate direction, by Henry Mitchell, one of 
the sub-assistants in the Coast Survey, with all desirable zeal and 
ability. Various causes had been assigned for this growth, by 
the action of the waves and winds sometimes on the outer side 
and sometimes on the inside of the Hook. The effect of the 
opening and closing of Shrewsbury Inlet had also been insisted 
n. ‘To examine these and other probable causes, laborious 
observations of tides and currents had been made in the vicinity 
at stations marked upon the map presented to the Association. 
Careful measurements of the low water line had also been made 
them are perfectly safe, and are of the highest importance. 
turns out that this growth of the Hook is not an accidental phenom- 
ena, but goes on regularly, and according to determinable laws. 
The amount of increase depends upon variable causes, but the 
general fact is, that it increases year by year; and the cause of 
this is a remarkable northwardly current, the amount and dura- 
tion of which these observations assign along both shores of the 
Hook, the outer one extending across the whole breadth of False 
Hook channel with varying velocity, and the one inside of the 
Hook extending nearly one-third of the distance across oy 
Hook ie _ These currents run to the north during both the ebb - 
and flood tide, with varying rates, and result from these tides 
