The light is then reflected by a distant mirror which reflects it back to the wheel. The Fizeau experiment was carried out by Hippolyte Fizeau in 1851 to measure the relative speeds of light in moving water. In 1849 French physicist Armand Fizeau developed a device known as the Fizeau wheel in order to measure the speed of light.
Given the rotational speed of the wheel and the distance between the wheel and the mirror Fizeau was able to calculate a value of 315000 kms for the speed of light.
Based on the number of teeth and speed of rotation of the toothed wheel and knowing the distance to the mirror he was able to calculate a speed of 315000 kms. In 1849 the French physicist Armand Fizeau created a new method to measure the speed of light more accurately using a rotating toothed wheel and a mirror as illustrated in the picture below. Based on the number of teeth and speed of rotation of the toothed wheel and knowing the distance to the mirror he was able to calculate a speed of 315000 kms. One lantern would shine signaling the other person to shine their lantern.