128 "Description and Use os the

Whence it is plain, that the central solarray is the only one which passes throughthe centers of the fun and earth, as wellas the only ray that can possibly be perpen-dicular to the earth’s surface; all othersolar parallel rays will fall more and moreoblique, as they are farther from the cen-tral ray, till their arrival at the edge of theenlightened disc, here represented by theinner edge of the broad paper circle, wherethey will become parallel to the horizonsof all places then under the said edge ofthe disc.

In one diurnal revolution of the earth,the central solar ray describes the parallelof the fun’s declination ; or rather that pa-rallel, to the inhabitants of which the funthat day will pass directly vertical, or overtheir heads.

From this application of the terrestrialglobe, we fee the natural cause of the diffe-rent altitudes of the fun at different timesof the day, and at different seasons of theyear j which arise from the earth’s dailyrotative and progressive motion, &c.

When we view the globe in this position,we at once fee the situation of all places in

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