  Some aspects of gravitational lensing by large scale structure (LSS) are
investigated. We show that lensing causes the damping tail of the cosmic
microwave background (CMB) power spectrum to fall less rapidly with decreasing
angular scale than previously expected. This is due to a transfer of power from
larger to smaller angular scales which produces a fractional change in power
spectrum that increases rapidly beyond $\ell \sim 2000$. We also find that
lensing produces a nonzero mean magnification of structures on surfaces of
constant redshift if weighted by area on the sky. This is a result of the fact
that light-rays that are evenly distributed on the sky oversample overdense
regions. However this mean magnification has a negligible affect on the CMB
power spectrum. A new expression for the lensed power spectrum is derived and
it is found that future precision observations the high-$\ell$ tail of the
power spectrum will need to take into account lensing when determining
cosmological parameters.
