  A new method for the determination of the extinction in our Galaxy is
proposed. The method uses surface brightnesses of external galaxies in the B
and R bands. The observational data have been taken from the ESO-LV galaxy
catalogue. As a first application of our model we derive the ratio of R band to
B band extinction. We introduce two methods for computing the ratio which give:
0.62 $\pm$ 0.05 (the first method) and 0.64 $\pm$ 0.06 (the second method)
which is in agreement with the recent literature value of 0.61. This agreement
confirms the validity and efficiency of our model and is an independent
verification for the standard value of the "total to selective extinction". The
method of extinction determination introduced in this paper will be explored in
subsequent publications.
