The following exercises have been proved to be practical by several years' use with classes of sixty to a hundred, handled in divisions of about fifteen, working two hours a week during the academic year. In this work the student is, whenever possible, left to draw his own conclusions from data discussed. The Ameri can Ephemeris is in constant use, photographs of objects in the sky furnish the specimens for inspection, and in this subject, as in botany or zoology, sharpening the pencil sharpens the eyes to draw the object fixes the attention upon details of structure. The graph is often used to show the relation between variables, and from it the student can often discover for himself great law's.
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