Because the air presses down with a force of fifteen pounds on every square inch of surface, and a column of water thirty-four feet high presses down with a force of fifteen pounds on every square inch of surface.
Does the weight of the air exactly balance the weight of the column of water?
It does; they balance each other.
Is water heavier than air?
Water is heavier than air; because a column of water thirty-four feet high weighs as much as a column of air fifty miles high.
Is quicksilver heavier than water?
Yes; quicksilver is about thirteen times heavier than water.
How high a column of quicksilver can the air keep up?
The air can keep up a column of quicksilver only thirty inches high.
Why is this?