

Photo: The Locomotive Publishing Co., Ltd. 



THE SPEED OF LIGHT 



A train travelling at the rate of sixty miles per hour would take rather more than seventeen and a quarter days to go round the earth 

 at the equator, i.e. a distance of 25,000 miles. Light, which travels at the rate of 186,000 miles per second, would take between one- 

 seventh and one-eighth of a second to go the same distance. 



ROTATING DISC OF SIR ISAAC NEWTON FOR 

 MIXING COLOURS 



The Spectroscope sorts out the above seven colours from 

 sunlight (which is compounded of these seven colours). If 

 painted in proper proportions on a wheel, as shown in the 

 coloured illustration, and the wheel turned rapidly on a pivot 

 through its centre, only a dull white will be perceived. If 

 one colour be omitted, the result will be one colour the result 

 of the union of the remaining six. 



