33 
Tapie VII 
Kilometers 
Nautical = 
miles 
0 1 2 3 | 4 5 6 7 8 9 
| 
0.0 1.9 3.7 5.6 7.4 9.3 zeal 13.0 14.8 16.7 
18.5 20. 4 22.2) 2A1 |} 25.9 27.8 29. 6 31.5 33.3 35, 2 
37.0 38.9 40.7 42.6 44.4 46.3 48. 2 50. 0 51.9 53. 7 
55. 6 57.4 59.3 61.1 63. 0 64.8 66. 7 68. 5 70.4 72.2 
T4.1 75.9 77.8 79.6 81.5 83.3 85. 2 87.0 88.9 90. 7 
92.6 94. 5 96.3 98. 2 100.0 101.9 103. 7 105. 6 107.4 109.3 
111.1 113.0 114.8 116.7 118.5 120.4 122.2 124.1 125.9 127.8 
129. 6 131.5 133.3 135. 1 137.1 138. 9 140. 8 142.6 144.5 146.3 
148. 2 150. 0 151.9 153. 7 155. 6 157.4 159.3 161.1 163. 0 164.8 
166. 7 168.5 170. 4 172. 2 174.1 175.9 177.8 179.6 181.5 183.3 
185. 2 187.1 188. 9 190.8 192. 6 194.5 196.3 198. 2 200. 0 201.8 
The velocity values as they are usually finally shown, represented 
by Go, page 31, are the differences between the movement on the 
surface and that at a level a 
where it is believed motionless 
water lies. But it is important 
to bear in mind that as a result 
of dynamic computations, the 
values of velocities are expressed 
in terms NORMAL TO THE 
VERTICAL SECTION which may 
include any two stations. 
Another step is necessary if it 
is desired to obtain the value of 
the real velocity. Let us as- 
sume that the direction of 
flow but not the rate is 
known. In Figure 14 suppose M, 
the direction of the current is Fic. 14—Lines AM and BM1 indicate the 
represented by the parallel __ie¥a det of he cretion. sore 
lnes AM and BM,, between tional line AB. To find: The true velocity 
the two stations A and B. Fur- upersthe current 
thermore, let it be given that the velocity normal to the section has been 
computed by means of equation (g), page 31, and that it is given on the 
figure as the lme K. We now wish to determine the true velocity, 
V, which hes in a direction parallel to the limes AM and BM,, and 
which forms the angle a with the computed velocity. The value of 
V, it is easy to see from the figure, is equal to — The same results 
a 
may be obtained graphically by laying off the angle a and dropping 
a perpendicular from the end point of the known side K upon the 
unknown side V, and then measuring the length of the latter in units 
the same as K. 
