four o'clock in the
morning
Shifting it certainly was . While the path it described as it swung blindly through the darkness , could not be laid down by any chart for want of a starting point , Barbican and his companions soon became aware of a decided modification of its relative position with regard to the Moon 's surface . Instead of its side , as heretofore , it now presented its base to the Moon 's disc , and its axis had become rigidly vertical to the lunar horizon . Of this new feature in their journey , Barbican had assured himself by the most undoubted proof towards four o'clock in the morning . What was the cause ? Gravity , of course . The heavier portion of the Projectile gravitated towards the Moon 's centre exactly as if they were falling towards her surface .