  Gravitational lens time delays depend on the Hubble constant, the observed
image positions, and the surface mass density of the lens in the annulus
between the images. Simple time delay lenses like PG1115+080, SBS1520+530,
B1600+434, PKS1830-211 and HE2149-2745 have H0 = A(1-<k>)+B<k>(e-1) where the
two coefficients A ~ 90km/s Mpc and B ~ 10km/s Mpc depend on the measured
delays and the observed image positions, <k> is the mean surface density in the
annulus between the images, and there is a small correction from the
logarithmic slope e ~ 2 of the surface density profile, k ~ R^(1-e), in the
annulus. These 5 systems are very homogeneous, since for fixed H0=100h km/s Mpc
they must have the same surface density, <k>=1.11-1.22 h +/- 0.04, with an
upper bound of 0.07 on any dispersion in <k> beyond those due to the
measurement errors. If the lenses have their expected dark halos, <k> ~ 0.5 and
H0=51+/-5 km/s Mpc, while if they have constant mass-to-light ratios, <k> ~
0.1-0.2 and H0=73+/-8 km/s Mpc. More complicated lenses with multiple
components or strong perturbations from nearby clusters, like RXJ0911+0551 and
Q0957+561, are easily recognized because they have significantly different
coefficients.
