Casting and Grinding a Speculum Metal Telescope Mirror — Newton's Reflecting Alloy
When Isaac Newton built his reflecting telescope in 1668, he needed a concave mirror to focus light — but silvered glass mirrors did not yet exist. Instead, he cast his mirror from speculum metal, a bronze alloy of approximately 68% copper and 32% tin that can be polished to a brilliant, highly reflective surface. Speculum metal had been known since antiquity — the Romans used it for hand mirrors (speculum is Latin for mirror) — but Newton was the first to grind it into a precise concave paraboloid for astronomical use. The alloy is hard, brittle, and takes a superb polish, but it tarnishes in air and must be periodically repolished. Every reflecting telescope before the 1850s used speculum metal mirrors, including William Herschel's great telescopes that discovered Uranus and mapped the Milky Way. This blueprint casts a speculum metal disc from copper and tin ingots, then grinds and polishes it into a concave mirror suitable for a Newtonian reflecting telescope.
Hazardous content
Ang blueprint na ito ay naglalaman ng mga mapanganib na proseso. Mag-log in at i-enable ang mapanganib na nilalaman sa iyong account settings upang makita ang step-by-step na mga tagubilin.
Kaugnay na Blueprint
Ang mga blueprint na ito ay nagbabahagi ng kaalaman — mga teknik, materyales, o prinsipyo
CC0 Pampublikong Domain
Ang blueprint na ito ay inilabas sa ilalim ng CC0. Malaya kang kumopya, magbago, mamahagi, at gumamit nang walang pahintulot.
Suportahan ang Maker sa pamamagitan ng pagbili ng mga produkto sa kanilang Blueprint Komisyon ng Maker itinakda ng mga Vendor, o lumikha ng bagong bersyon ng Blueprint na ito at isama bilang koneksyon sa iyong Blueprint upang ibahagi ang kita.