New, rigorous, upper and lower limits to pressure in outer layers of s
pherically symmetric mass distributions in hydrostatic equilibrium are
presented. Upper and lower limits to general integrals of stellar var
iables are obtained and illustrated. The pressure inequalities transla
te into rigorous, upper and lower limits for velocity dispersion in is
otropic, spherically symmetric stellar systems. They set lower limits
to gravitational masses of galaxies in terms of the X-ray temperatures
of the gas they contain.