  We determine and tabulate A(lambda)/A(K), the wavelength dependence of
interstellar extinction, in the Galactic plane for 1.25um<lambda<8.0um along
two lines of sight: l~42 and l~284. The first is a relatively quiescent and
unremarkable region; the second contains the giant HII region RCW 49 as well as
a ``field'' region unrelated to the cluster and nebulosity. Areas near these
Galactic longitudes were imaged at J, H, and K bands by 2MASS and at 3--8um by
Spitzer for the GLIMPSE Legacy program. We measure the mean values of the color
excess ratios (A(lambda)-A(K))/(A(J)-A(K)) directly from the color
distributions of observed stars. The extinction ratio between two of the
filters, e.g. A(J)/A(K), is required to calculate A(lambda)/A(K) from those
measured ratios. We use the apparent JHK magnitudes of giant stars along our
two sightlines, and fit the reddening as a function of magnitude (distance) to
determine A(J)/kpc, A(K)/kpc, and A(J)/A(K). Our values of A(lambda)/A(K) show
a flattening across the 3--8um wavelength range, roughly consistent with the
Lutz 1996 extinction measurements derived for the sightline toward the Galactic
center.
