dz + dp/G = 0;
.: z + p/G = constant; (3)
or the pressure varies hydrostatically as in a fluid at rest. For two
stream lines in a horizontal plane, z is constant, and therefore p is
constant.
[Illustration: FIG. 35.]
_Radiating Current._--Suppose water flowing radially between
horizontal parallel planes, at a distance apart = [delta]. Conceive
two cylindrical sections of the current at radii r1 and r2, where the
velocities are v1 and v2, and the pressures p1 and p2. Since the flow
across each cylindrical section of the current is the same,