Newtonian telescope Newtonian telescope The Newtonian telescope, also called the Newtonian reflector or just the Newtonian, is a type of reflecting telescope invented by the English scientist Sir Isaac Newton (1642–1727), using a concave primary mirror and a flat diagonal secondary mirror. Newton's first reflecting telescope was completed in 1668 and is the earliest known functional reflecting telescope. The Newtonian telescope's simple design makes it very popular with amateur telescope makers. Newton's idea for a reflecting telescope was not new. Galileo Galilei and Giovanni Francesco Sagredo had discussed using a mirror as the image forming objective soon after the invention of the
Woodwind instrument Woodwind instrument Woodwind instruments are a family of musical instruments within the more general category of wind instruments. There are two main types of woodwind instruments: flutes and reed instruments (otherwise called reed pipes). What differentiates these instruments from other wind instruments is the way in which they produce their sound. All woodwinds produce sound by splitting an exhaled air stream on a sharp edge, such as a reed or a fipple. A woodwind may be made of any material, not just wood. Common examples include brass, silver, cane, as well as other metals such as gold and platinum. Occasionally