  Results from the third campaign of a ground-based multi-band observation of
the millimeter emission of the sky from Tenerife (Canary Islands) are
presented. The instrument consists of a 0.45 meter diameter off-axis telescope
equipped with a 4-band multi-mode $^3He$ cooled photometer working at 1.1, 1.3,
2.1 and 3.1{\notetoeditor{These are effective wavelengths}} mm wavelengths. The
beam is well approximated by a Gaussian with 1$% ^{o}$.35 Full Width Half
Maximum (FWHM) at all wavelengths. The wide wavelength coverage of our
instrument allows us to characterize and reduce both the atmospheric and
galactic contamination in our data. The CMBR data is analyzed in 6 multipole
bands whose centers span the range $\ell=39$ to $\ell =134$ at the two longest
wavelengths (2.1 and 3.1 mm). A likelihood analysis indicates that we have
detected fluctuations in all bands at the two wavelengths. We have evidence of
a rise in the angular power spectrum from low $\ell $ to high $\ell $. Our
measured spectrum is consistent with current popular theories of large scale
structure formation, COBE, and other recent balloon-borne experiments with
similar wavelength coverage.
