let do_measurement time =
      let (print, draw) = Experiment1.do_measurement ~time in
      if with_drawings then
        begin
          if step_by_step then
            begin
              Printf.printf "  -  Press a key...%!";
              ignore (Graphics.read_key ());
              Printf.printf "\013%!"
            end;
          draw (time - time_transient);
          Graphics.synchronize ();
          if snapshot_now time then
            ( |> )
              (Images.Rgb24
                 (Graphic_image.get_image 0 0 (Graphics.size_x ())
                    (Graphics.size_y ())))
              (Images.save
                 (Printf.sprintf "%s_step%0*i.png" snapshot_name time_width
                    time)
                 None [])
        end;
      print time