chi

The quantity Ω/χ which appears in many hydraulic equations is called the hydraulic mean radius of the pipe.

In the native words “x” should be given the sound of the Greek χ.

Thus the Romans, when they would express the sound of the Greek θ and of χ, for want of suitable characters, wrote th and ch.

The symbol χ expresses the energy of unit of mass of the liquid at a depth ν within the bounding surface.

Both ρ and χ are functions of z, the value of which remains the same when z − c is substituted for z.