  Behavior of individual molecules of normal and heavy water in beryl single
crystals was studied by $^1$H and $^2$H nuclear magnetic resonance
spectroscopy. From temperature dependences of the spectra we deduce that type-I
water molecules embedded in the beryl voids are oriented quite differently from
the view established in the literature. Namely, contrary to earlier
assumptions, their H-H lines deviate by about 18$^\circ$ from the hexagonal
axis. We suggest that this is due to the molecules attaching to the oxygen
atoms forming the beryl structural voids by a hydrogen bond. Our analysis shows
that the molecules perform two types of movement: (i) rapid librations around
the axis of the hydrogen bond, and (ii) less frequent orientational jumps among
the twelve possible binding sites in the beryl voids. The frequencies of the
librational motions are evaluated from a simple thermodynamic model, providing
a good quantitative agreement with the frequencies of librations from optical
experiments reported earlier.
