In http://arxiv.org/pdf/gr-qc/0103044v5.pdf in page 6 it is written about a tidal forces on a sphere built up from test particles. It is written that ball also starts to being squashed in the horizontal directions. I do not understand this. Because gradient of gravitational force is mainly in vertical direction. Is it also in horizontal direction? What is mechanism for squashing in horizontal direction? Is here at this ball of test particles any distinction to the tide on earth caused by moon?