  Magnetization and susceptibility studies on single crystals of the pyrochlore
Ho$_{2}$Ti$_{2}$O$_{7}$ are reported for the first time. Magnetization
isotherms are shown to be qualitatively similar to that predicted by the
nearest neighbor spin-ice model. Below the lock-in temperature, $T^{\ast
}\simeq 1.97$ K, magnetization is consistent with the locking of spins along
[111] directions in a specific two-spins-in, two-spins-out arrangement. Below
$T^{\ast}$ the magnetization for $B||[111]$ displays a two step behavior
signalling the breaking of the ice rules.
