Herschel's 'large' 10-foot telescope, artwork. This telescope was designed by the German-born British astronomer William Herschel (1738-1822). The tube was 10 feet (3 metres) long, but was larger in overall size than the smaller 10-foot model (see R102/174). It is mounted on wheels on a circular base so it can be rotated. A rope and pulley system is used to adjust the angle. The observer would use a ladder to make observations by looking down an eyepiece on the side of the tube (centre left) at an image that was projected to the side by the primary mirror in the base of the telescope. The mirror was made of polished metal, instead of glass. This was one of more than 400 telescopes designed and built by Herschel, whose discoveries included Uranus (1781) and several moons of Saturn and Uranus.