  Ultraviolet spectra were taken of 25 Detached Eclipsing Binaries (DEBs) with
spectral types O, B, and early A with the International Ultraviolet Explorer
(IUE) satellite in the 1150 to 1900 ${\AA}$ region. The spectra were compared
with BOSZ model atmospheres (Bohlin, et al. 2017). The composite spectra of the
DEBs were modeled by a combination of models representing the hot and cool
components, and the temperatures of the hottest components of the systems were
determined. From these temperatures a direct Mass-Temperature relation was
obtained for stars close to the main sequence with solar metallicity for B and
early A stars: log M/Msun = -5.90 $\pm$ 0.27 + (1.56 $\pm$ 0.07) x log T This
relation allows a mass to be inferred for comparable stars from an ultraviolet
spectrum. The five chemically peculiar Am stars in the sample have larger radii
than normal A stars of the same mass.
