Initially, a hand held tube, compound microscopes were soon mounted to a side pillar with a base so they could be rotated at an angle and objects illuminated with a magnifying glass on a stand known as a bulls eye condensing lens. Around 1855 large, elegant binocular microscopes with dual eyepieces on twin body tubes that converge into a single tube with a single objective appeared on the market. They were meant to alleviate eyestrain because of stereoscopic viewing. They were generally accompanied by abundant accessories but were unpopular for serious research due to delicacy and inconsistent optics. From the 1870s some instruments were made of nickel silver or nickel brass and oxidized brass was used on some microscope feet and posts Black enamelled steel or brass became popular in the 1890s.