P² = 4(a² + [lambda]) (b² + [lambda]) (c² + [lambda]). (10)

With the values above of u, v, w, u´, v´, w´, the equations become of

the form

1 dp

----- -- + 4[pi][rho]Ax + [alpha]x + hy + gz = 0, (11)

[rho] dx

1 dp

----- -- + 4[pi][rho]By + hx + [beta]y + fz = 0, (12)

[rho] dy

1 dp

----- -- + 4[pi][rho]Cz + gx + fy + [gamma]z = 0, (13)

[rho] dz

and integrating

p[rho]^(-1) + 2[pi][rho](Ax² + By² + Cz²)

+ ½([alpha]x² + [beta]y² + [gamma]z² + 2fyz + 2gzx + 2hxy) = const., (14)

so that the surfaces of equal pressure are similar quadric surfaces,

which, symmetry and dynamical considerations show, must be coaxial

surfaces; and f, g, h vanish, as follows also by algebraical

reduction; and

4c²(c² - a²) / c² - a² \²

[alpha] = ------------[Omega]2² - ( -------[Omega]2 - [eta] )

(c² + a²)² \ c² + a² /

4b²(a² - b²) / a² - b² \²

- ------------[Omega]3² - ( -------[Omega]3 - [zeta] ), (15)

(a² + b²)² \ a² + b² /

with similar equations for [beta] and [gamma].

Encyclopaedia Britannica, 11th Edition, "Hydromechanics" to "Ichnography" Volume 14, Slice 2 · 第 50 / 120 题