It was now near the evening. Alexander sent forward a strong reconnoitering party, ordering them to proceed cautiously, to ascend eminences and look far before them, to guard carefully against surprise, and to send back word immediately if they came upon any traces of the enemy. At the present day the operations of such a reconnoitering party are very much aided by the use of spy-glasses, which are made now with great care expressly for military purposes. The instrument, however, was not known in Alexander's day.