Wire Maze Electricity DIY STEM Kit
$9.99$5.95
The mean radius of the earth is approximately 6.4 million meters (exact = 6.37 x 106 m). Its volume is then:
'To myself I seem to have been only like a boy playing on the seashore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me.'