76 SCIENTIFIC RECREATIONS. An index hand, RR, moves round a dial apparatus for measuring angles. instru- like the hand of a clock, and the ment is used by gazing first at one of •.— the two objects, between which the ft*----::;""" Jv — angle we wish to determine is made — like the church steeples… … Fig. sop-Measuring angles. shown in the cut (fig. 5 i o). This was so arranged that when any object in the horizon was being looked at through the telescope attached, a plummet line is at o°. But if the telescope be raised to C S, the quadrant will move, and the line will mark a certain number of…
Scientific recreations
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