Until the late 1800s what was the
purpose of a secondary education in
the United States?

To prepare students for college

The students of secondary classes were meant to teach those in primary ones.

Explanation:

I hope this is correct, I am just using some of my knowledge previously.

norsemen from northern countries had made earlier journeys

incident infrared radiation is blocked. visible and ultraviolet radiation heat   earth.

earth radiates infrared radiation. infrared radiation is blocked and heats earth. visible and shortwave radiation heat earth.

earth radiates longwave radiation

longwave radiation is reflected downward longwave radiation heats earth