When a cloud overcharged with electric fluid approaches another which is undercharged, the fluid rushes from the former into the latter, till both contain the same quantity.
Is there any other cause of lightning besides the one just mentioned?
Yes; sometimes mountains, trees, and steeples will discharge the lightning from a cloud floating near, and sometimes the electricity passes from the earth into the clouds.
How high are the lightning clouds from the earth?
Sometimes they are elevated four or five miles high, and sometimes actually touch the earth with one of their edges; but they are rarely discharged in a thunder storm when they are more than seven hundred yards above the surface of the earth.
What is a thunder storm?
The disturbance caused in the air when successive discharges of accumulated electricity take place.
Into how many kinds has lightning been divided?
Three.
What are they?