"You find this odd contraption lost in the brush near an extinguished fire. You stick the Telescope to your eye and nearly fall over as a distant hill comes right at you. No, the hill didn't moved, just your vision. What an ingenious device!"
The Telescope is an artifact from Heroes of Might and Magic IV that gives the hero +1 scouting radius.
The Telescope allows a hero to see further, and this is always a good thing. Scouts will find this artifact especially handy, but every army enjoys the Telescope. The ability to see further allows heroes to spot mines and other locations of interest easier and faster. This is one of the few items that are worth being kept even after better replacements are found. Having Expert Scouting, a +2 scouting radius artifact and the Telescope doesn't hurt.