  The superconductor Nb$_3$Sn has a high critical temperature and high critical
field, widely used for high-field superconducting magnets. In this work we
investigate its microscopic electronic structure with $^{93}$Nb nuclear
magnetic resonance (NMR). The high-quality Nb$_3$Sn powder sample was studied
in both 3.2T and 7T magnetic fields in the temperature range from 1.5K to 300K.
From measurement of the spectrum and its theoretical analysis, we find evidence
for anisotropy despite its cubic crystal structure. This anisotropy is manifest
in alignment of powder grains under certain temperature and field cycling
conditions. The Knight shift and spin-lattice relaxation rate, $T_1^{-1}$, were
measured in the normal state. Additionally, $T_1^{-1}$ was measured in the
superconducting state and compared with BCS theory revealing a weak field
dependence, with an energy gap $\Delta(0)=2.0\pm0.08k_B T_c$ at 3.2T and
$\Delta(0)=1.73\pm0.08k_B T_c$ at 7T, indicating suppression of the order
parameter by magnetic field.
