  We report on a measurement of the angular power spectrum of the anisotropy in
the Cosmic Microwave Background. The anisotropy is measured in 23 different
multipole bands from l=54 (~3 deg) to l=404 (~0.45 deg) and in 6 frequency
bands from 26 GHz to 46 GHz over three observing seasons. The measurements are
consistent from year to year. The frequency spectral index of the fluctuations
(measured at low l) is consistent with that of the CMB and inconsistent with
either dust or Galactic free-free emission. Furthermore, the observations of
the MSAM1-92 experiment (Cheng et al. 1994) are repeated and confirmed. The
angular spectrum shows a distinct rise from dT_l =
\sqrt{l(2l+1)<|a^m_l|^2>/4pi} = 49(+8,-5) \uK at l=87 to dT_l=85(+10,-8) uK at
l = 237. These values do not include an overall +/-14\% (1sigma) calibration
uncertainty. The analysis and possible systematic errors are discussed.
