- Phonograph (Wikipedia)
A phonograph, later called a gramophone (as a trademark since 1887, as a generic name in the UK since 1910), and since the 1940s a record player, or more recently a turntable, is a device for the mechanical and analogue reproduction of recorded sound. The sound vibration waveforms are recorded as corresponding physical deviations of a helical or spiral groove engraved, etched, incised, or impressed into the surface of a rotating cylinder or disc, called a “record”. To recreate the sound, the surface is similarly rotated while a playback stylus (or “needle”) traces the groove and is therefore vibrated by it, faintly reproducing the recorded sound. In early acoustic phonographs, the stylus vibrated a diaphragm that produced sound waves coupled to the open air through a flaring horn, or directly to the listener’s ears through stethoscope-type earphones.
- Messier 25 (Wikipedia)
Messier 25, also known as IC 4725, is an open cluster of stars in the southern constellation of Sagittarius. The first recorded observation of this cluster was made by Philippe Loys de Chéseaux in 1745 and it was included in Charles Messier’s list of nebulous objects in 1764. The cluster is located near some obscuring features, with a dark lane passing near the center.
