A Catechism of Familiar Things; / Their History, and the Events Which Led to Their Discovery. / With a Short Explanation of Some of the Principal Natural Phenomena. For the Use of Schools and Families. Enlarged and Revised Edition.

by Anonymous

Expansion, extending or spreading out.

What is Twilight?

The light from the first dawning of day to the rising of the sun; and again between its setting and the last remains of day. Without twilight, the sun's light would appear at its rising, and disappear at its setting, instantaneously; and we should experience a sudden transition from the brightest sunshine to the profoundest obscurity. The duration of twilight is different in different climates; and in the same places it varies at different periods of the year.

Instantaneously, done in an instant, in a moment's time.

Obscurity, darkness, want of light.

How is it produced?

By the sun's refraction—that is, the variation of the rays of light from their direct course, occasioned by the difference of density in the atmosphere.

Variation, change.

Density, closeness of parts, compactness.

What is the poetical name for the morning Twilight?