A high-school astronomy: in which the descriptive, physical, and practical are combined .. (1853)
Mattison, Hiram, 1811-1868 · New York, F. J. Huntingdon [etc.] · leaf 21
fluous, the substance of them being already sufficiently understood. With suchstudents the judicious teacher will pass rapidly over the next ten pages, or omit themaltogether. 14. Define a solid,, or body—a surface. How many kinds of surfaces ?(Any other distinctions ?) What is a plane surface ?… … Perpendicular Planes aresuch as stand exactly uprightupon each other, or cross eachother at right angles. In the figure, one plane is placed horizontally,and the other perpendicular to it. They aretherefore perpendicular to each other, howeverthey may stand in relation to the observer. Inclined…
Astronomy
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