History of the telescope a wider field of view than a classic Cassegrain. During the period 1850–1900, reflectors suffered from problems with speculum metal mirrors, and a considerable number of "Great Refractors" were built from 60 cm to 1 metre aperture, culminating in the Yerkes Observatory refractor in 1897; however, starting from the early 1900s a series of ever-larger reflectors with glass mirrors were built, including the Mount Wilson 60-inch (1.5 metre), the 100-inch (2.5 metre) Hooker Telescope (1917) and the 200-inch (5 metre) Hale telescope (1948); essentially all major research telescopes since 1900 have been reflectors. A number of 4-metre class (160 inch)
Sky & Telescope separate magazines, "The Sky" and "The Telescope". In 2005, Sky Publishing Corporation was acquired by New Track Media, a portfolio company of the private equity firm Boston Ventures. In 2014, New Track was sold to F+W Media. The magazine played an important role in the dissemination of knowledge about telescope making, through the column "Gleanings for ATMs" that ran from 1933 to 1990. Its main competitor is "Astronomy". Sky & Telescope Sky & Telescope (S&T) is a monthly American magazine covering all aspects of amateur astronomy, including the following: The articles are intended for the informed lay reader and include