618. Why has the thunder-peal sometimes a low grumbling noise?
Because the electrical discharges, though violent, take place far away, and the vibrations of the air become subdued.
619. Why does the thunder-peal sometimes follow immediately after the flash of lightning?
Because the discharge of electricity takes place near the hearer.
620. Why does the thunder-peal sometimes occur several seconds after the flash?
Because the discharge takes place far away, and light travels with a much greater velocity than sound.
621. Through what distance will the sound of thunder travel?
Some twenty or thirty miles, according to the direction of the wind, and the violence of the peal.
622. Through what distance will the light of lightning travel?