  In terms of spinless fermions via the Jordan-Wigner transformation along a
snake-like path and spin waves modified so as to restore the sublattice
symmetry, we investigate static and dynamic properties of two-leg
antiferromagnetic Heisenberg ladders. The specific heat is finely reproduced by
the spinless fermions, whereas the magnetic susceptibility is well described by
the modified spin waves. The nuclear spin-lattice relaxation rate is discussed
in detail with particular emphasis on its novel field dependence.
