In a Brans-Dicke (BD) cosmological model, the energy density associated wit
h some scalar field decreases as a(-2[(omega 0+1/2)/(omega 0+1)]) with the
scalefactor a(t) of the universe, giving matter with an equation of state p
= -(1/3) [(2 + omega(0))(1 + omega(0))]rho. In this model, the universe co
uld be closed but still have a non-relativistic matter density correspondin
g to its critical value, Ohm(0) = 1. Different cosmological expressions, su
ch as luminosity distance, angular diameter, number count and ratio of the
redshift thickness-angular size, are determined in terms of the redshift fo
r this model.