48 EFFECTS OF WINDS AND OF 



Each value shown in the seventh column is the product of the two quanti- 

 ties in that line entered in the fourth and sixth columns. Each value in the 

 seventh column is rounded off to three significant figures, as that gives 

 sufficient accuracy. 



The continuous sum shown in the last column of table No. 9 was started 

 at the extreme eastern part of Lake Erie and carried forward continuously, 

 and was rounded off to three significant figures after the summation had been 

 made continuously. 



DETERMINATION OF POSITION OF NODAL LINE. 



The values of 2 shown in the fifth and sixth columns of table No. 9 

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are all referred to the extreme eastern part of Lake Erie, near Buffalo. For 

 use in formula (59) it is necessary to have these summations referred to the 

 nodal point on the line of disturbed elevations of the water surface, such 

 as is indicated by the point G in figure 1, plate 4. Hence, the location of 

 this point G must be determined. 



Figure 1, plate 4, is drawn for a west wind. It shows the disturbed water 

 surface depressed to the westward of G and elevated to the eastward. It is 

 clear that if the wind were from the east the disturbed water surface would 

 be depressed to the eastward of the nodal point, G, and elevated to the west- 

 ward. The ultimate effect of a steady east wind is to transfer water from 

 portions of the lake lying to the eastward of the nodal point to portions of 

 the lake lying to the westward of that point. 



In the computation of which selected parts are shown in table No. 9 the 

 summations shown in the fifth, sixth, and eighth columns are all referred to 

 an initial point at the extreme eastern part of the lake at the water surface. 

 This point is the lowest point of the disturbed water surface under the in- 

 fluence of an east wind. Let the total disturbance of elevation of the water 

 by an east wind at this particular point, which has been used as the initial 

 point, be called Hi. 



The total amount of water in the lake which is above the elevation of this 

 initial point in the disturbed condition under the influence of an east wind is 



S (area of strip) (CiS ) (60) 



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In (60) the outer S stands for a summation, strip by strip for the strips 

 shown in the computations illustrated in tables Nos. 8 and 9, of the products 



of the area of each strip by the quantity CiS- for that strip. This 



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summation is supposed to start at the initial point and to extend over the 



whole lake. So, too, the summation S- for each strip is supposed to 



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start at the same initial point, but is supposed to stop for each strip at that 



