  We propose a cloak for coupled shear and pressure waves in solids. Its
elastic properties are deduced from a geometric transform that retains the form
of Navier equations. The spherical shell is made of an anisotropic and
heterogeneous medium described by an elasticity tensor C' (without the minor
symmetries) which has 21 non-zero spatially varying coefficients in spherical
coordinates. Although some entries of C, e.g. some with a radial subscript, and
the density (a scalar radial function) vanish on the inner boundary of the
cloak, this metamaterial exhibits less singularities than its cylindrical
counterpart studied in [M. Brun, S. Guenneau, A.B. Movchan, Appl. Phys. Lett.
94, 061903 (2009).]
  In the latter work, C' suffered some infinite entries, unlike in our case.
Finite element computations confirm that elastic waves are smoothly detoured
around a spherical void without reflection.
