An introduction to astronomy : designed as a text book for the students of Yale College (1846)
Olmsted, Denison, 1791-1859, Yale College (1718-1887) · New York : Collins, Brother & Co. · leaf 80
d be obtained by asingle reading. In a circle of six feet diameter, like that repre-sented in the figure, the divisions may be easily carried to fiveminutes each. The microscope (which is of the variety calledcompound microscope) forms an enlarged image of each of thesedivisions in the focus of the… … in a direction parallel to the divisions of the limb, and which is soadjusted to the screw as to move over the whole magnified spaceof five minutes by five revolutions of the screw. Of course onerevolution of the screw measures one minute. Moreover, if thescrew itself is made to carry an index…
Astronomy
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