INVESTIGATION OF OYSTER SPAWNING, ETC., MILFORD, CONN. 455 



will be transported back to it. This consideration has a bearing on the distribution 

 and occurrence of oyster larvaj in the harbor and Sound, which will be discussed later. 

 Briefly summarized, the chief chatacteristics of the tides and currents in Milford 

 Harbor are as follows: 



1. The mean range of tide is 6.6 feet. 



2. With spring tides the maximum range recorded during the summer was 9 

 feet, while with neap tides the minimum range was 4.2 feet. 



3. The tide is of the semidiurnal type and possesses the general characteristics 

 of the Atlantic Ocean tide, as described previously. 



4. The tidal currents are of the rectilinear or reversing type. 



5. The duration of the flood current is approximately 5J4 hours, and of the ebb 

 current 6 hours. 



6. The currents attain their greatest velocity when the tide is halfway between 

 high and low water mark. 



7. The velocity of the ebb current is approximately one-third greater than the 

 velocity of the flood current. 



8. The period of slack water, or zero velocity, occurs at the times of high and 

 low water. With neap tides, slack water lasts for an interval of about 1 hour, and 

 with spring tides only 20 minutes. 



TIDES AND CURRENTS IN LONG IgLAND SOUND 



Studies of the tides and currents were not confined entirely to Milford Harbor 

 but were carried on in Long Island Sound also, as this is the largest and most im- 

 portant seed-oyster producing region in the north. Here the tidal currents are rather 

 complex, and, in order to study them, several experiments were made with drift 

 bottles in addition to the current-meter observations. 



The current-meter observations consisted of determinations of the velocity and 

 direction of the current at various stages of the tide and were made at two stations 

 off Milford. Observations made during ebb tide showed that the predominant 

 direction of the current during this period was E. 20° S., and that the maximum veloc- 

 ity was 0.9 foot per second. During the flood tide the current does not run in one 

 general direction but swings to the right through an arc of 140° from low water to 

 high water. The direction and velocity at four stages of the flood tide are as follows: 



Table 6 



Predominat- 

 ing direction 



Velocity 

 (linots) 



First-quarter flood. . . 

 Second-quarter flood. 

 Third-quarter flood... 

 Fourth-quarter flood. 



W. 20°N 



W. 40° N 



N. 40° E 



N. 70° E 



0.25 

 .85 



1.15 

 .30 



The veering of the current to the right during this flood cycle can be attributed 

 to two chief causes: (1) The rotation of the earth, in consequence of which all 

 moving bodies are impressed with a force that, in the Northern Hemisphere, 

 deflects them to the right of the direction in which they are moving. The water 



