The velocity of sound was determined in helium on 14 equally spaced isotherms from -175 deg to 150 deg c and at pressures from 10 to 150 atm. The results were correlated with an abbreviated perturbation equation of state which employs both the Lennard-Jones (n,6) and the exponential repulsion potentials. Six parameters in the equation of state were adjusted to fit the velocity data within the experimental precision of about 0.0001%. The derived results reliably predict literature (p, V, t) values and other velocity-of-sound data for pressures as high as 7,000 atm and for temperatures from -223 deg to 577 deg c. A value of the gas constant was derived, r=8,314.79+/- 0.35 Jk-1 lmpl-1, which is statistically consistent with the accepted value. The results also support a recent gas thermometry result that indicates the 1968 temperature scale may be in error by 0.012 K at -183 deg c.