of the clouds, tries to calculate the electric potential necessary for lightning, records the depth and weight of water precipitated by the storm, and thereby learns that there are several distinct kinds of whirling air that produce thunderstorms.
Contrast, therefore, ancient and modern thought. Our ancestors saw in a thunderstorm the conflict between a many-headed, hairy monster, with the sun, or with a being of superhuman strength and attributes, throwing lightning and thunderbolts about. Such an attitude of mind can only induce terror.
Now, when we see a thunderstorm we might observe a wind coming from the W. overhead, while we were oppressed by a stuffy S.E. breeze; and note a squall from the S.W. with a velocity of sixty miles an hour just as the rain commenced. Then we might measure the height of the lower base of the clouds and find it not more than five thousand feet above the earth, while the rocky summits rise no less than fifteen thousand feet above the ground, and the rain-gauge might show that water to the depth of three inches fell out of these ten thousand feet of cloud.
Fear and terror are unknown and almost inconceivable to a man who looks at nature from this point of view.
But the moral effect of weighing and measuring is so great I should like to give you another illustration.
Poets are fond of describing big waves; they talk about mounting on them up to the heavens and then descending to the depths. Painters draw waves of impossible height and steepness, and the influence of both the artist and the poet is to exaggerate any natural fear at first seeing a big wave.
But if you stand on a ship's deck with a couple of chronographs to measure the length and speed of the waves, you find that an exceptionally big wave is only four hundred feet long from crest to crest, and travelling at a rate of thirty- six miles an hour; while your aneroid shows that the height from trough to crest is only forty feet. Then, if you are mathematically inclined, you can calculate like our distinguished countryman the late Professor Rankine that the curve of wave shape is what is called a trochoid; that unless the crest breaks, a ship can ride safely over the highest sea.
