  The detection by the HESS atmospheric Cherenkov telescope of fifteen new
sources from the Galactic plane makes it possible to estimate the contribution
of unresolved point sources like those detected by HESS to the diffuse Galactic
emission measured by EGRET and recently at higher energies by the Milagro
Collaboration. Assuming that HESS sources have all the same intrinsic
luminosity, the contribution of this new source population can account for most
of the Milagro $\gamma$-ray emission at TeV energies and between 10 and 20 per
cent of EGRET diffuse Galactic $\gamma$-ray emission for energies bigger than
10 GeV. Also, by combining the HESS and the Milagro results, constraints can be
put on the distribution and the luminosities of gamma ray emitters in the
Galaxy.
