  Context. The Sagittarius (Sgr) dwarf spheroidal galaxy is currently being
disrupted under the strain of the Milky Way. A reliable reconstruction of Sgr
star formation history can only be obtained by combining core and stream
information. Aims. We present radial velocities for 67 stars belonging to the
Sgr Stream. For 12 stars in the sample we also present iron (Fe) and
$\alpha$-element (Mg, Ca) abundances. Methods. Spectra were secured using
different high resolution facilities: UVES@VLT, <EMAIL_ADDRESS>and SARG@TNG.
Radial velocities are obtained through cross correlation with a template
spectra. Concerning chemical analysis, for the various elements, selected line
equivalent widths were measured and abundances computed using the WIDTH code
and ATLAS model atmospheres. Results. The velocity dispersion of the trailing
tail is found to be $\sigma$=8.3$\pm$0.9 km s$^{-1}$, i.e., significantly lower
than in the core of the Sgr galaxy and marginally lower than previous estimates
in the same portion of the stream. Stream stars follow the same trend as Sgr
main body stars in the [$\alpha$/Fe] vs [Fe/H] plane. However, stars are, on
average, more metal poor in the stream than in the main body. This effect is
slightly stronger in stars belonging to more ancient wraps of the stream,
according to currently accepted models of Sgr disruption.
