Thus it can be seen that the formula as corrected by the introduction of the 

 third harmonic in not deviating more than plus or minus 2% is sufficiently- 

 accurate to be used in tidal work where a like accuracy is seldom approached, 



APPLICATION OF FORMULA 



On reviewing a new formula, the first thought which comes to one's mind 

 is the question of its adaptability to current engineering problems. Conse- 

 quently an effort will be made to show a method of application and comparison 

 of the results with actual gaged data 



First, let it be assumed that Nantucket Inlet is being studied and that 

 it is desirable to know the maximum quantity of water which may be expected 

 to pass through the inlet during the afternoon of 29 December 1933. .Inasmuch 

 as the tidal prism of the inner basin is equal to the area of the basin multi- 

 plied by the range in tide, the area of the basin was planimetared from No S„ 

 Co k 0. So Chart No. 1209 and the tidal range for the afternoon of 29 December 

 1938 was taken from the predicted tides in the Uo 5, Co & Go Go tide tables 

 for 1933. The area as measured from the chart was found to be 190,000,000 

 square feet, while the tidal range was found to be 2.3 feet. Consequently the 

 tidal prism as computed is 437,000,000 cu. ft. Substituting this value of V 

 in the formula, Q m = 0.86 -j^ - it is found that the maximum quantity of water 

 that may be expected to flow through the inlet on the afternoon of 29 December 

 1933 is 26,300 ou. ft. per sec. This discharge when compared with the gaged 

 value of ^ m given in table 2 shows a deviation of only 0.75$» The remarkable 

 agreement of the observed and computed maximum discharges should not be con- 

 strued to mean that the formula will work equally well for any inlet under 

 all conditions. In the first place the determination of the area of the inner 

 basin can only be determined accurately when the inner pas in is well defined 

 such as Nantucket Harbor. Consequently, as the inner basins become more com- 

 plex such as that at Eeaufort Inlet, the accuracy of the application of the 

 formula depends wholly on one's ability to choose the lodal points in the 

 various bodies of water which make up the inner basin . In other words, the 

 value of the application of the formula decreases as the inner basin increases 

 in complexity. In addition to the limitations of accurately determining the 

 area of the inner basin there Is always the possibility that the predicted 

 range of the tide for a specific day as read from the U, 3. Co fk G. 3. Tide 

 tables will be altered by strong persistent winds. It can be seen, however, 

 that a few tide gages advantageously placed in the inner basin will assist in 

 making a more accurate estimate of the limits of the inner basin and also 

 give accurate tidal ranges. 



CONCLUSION 



In presenting this monograph no effort has been made to show that the 

 formula developed will necessarily eliminate inlet gaging, but it has merely 

 been presented as an additional working tool to be used by engineers when 

 applicable. 



21 



