Telescope Alidade

  • Exhibition Text

    • Brass, silver

      Late 17th century, France

      This instrument, with vertically swinging telescope, measures distances. Setting it on a plane table, the surveyor used the scaled position to draw and measure lines representing sightlines from two positions. Drawing the connecting base line completed a triangle with sides proportional to actual distances.

      AMNH Hayden Planetarium Collection 2034

      Show more