Early navigational techniques employed observations of the sun, stars, waves and birdlife. In the 15th century, the Chinese were using the magnetic compass to identify direction of travel. By the 16th century in Europe, navigational instruments included the quadrant, the astrolabe, cross staff, dividers and compass. By the time of the Age of Exploration these tools were being used in combination with a log to measure speed, a lead line to measure soundings, and a lookout to identify potential hazards. Later, an accurate marine sextant became standard for determining latitude and an accurate chronometer became standard for determining longitude.