Convert from furlong/hour [survey] to speed of light [glass]

Unit Definition (furlong/hour [survey])

Unit Definition (speed of light [glass])
The speed of light in a vacuum is exactly equal to 299,792,458 metres per second (approximately 186,282.4 miles per second). The speed of light is denoted by the letter c, reputedly from the Latin celeritas, "speed", and also known as Einstein's constant. This exact speed is a definition, not a measurement, as the metre itself is defined in terms of the speed of light and the second.