. Elements of theoretical and descriptive astronomy, for the use of colleges and academies. Fig. Fig. 9. the threads of the screw, thus making the number of teeth passedover by the spider threads equal to the number of complete revolutions made by the screw. The central notch is taken as thepoint of reference, and is distinguished by a hole opposite to is a fixed index at i, to which the divisions on the head ofthe screw are referred. When any division of the limb does notcoincide with the central notch, the spider threads are movedfrom the central notch to the division, and the n
. Elements of theoretical and descriptive astronomy, for the use of colleges and academies. Fig. Fig. 9. the threads of the screw, thus making the number of teeth passedover by the spider threads equal to the number of complete revolutions made by the screw. The central notch is taken as thepoint of reference, and is distinguished by a hole opposite to is a fixed index at i, to which the divisions on the head ofthe screw are referred. When any division of the limb does notcoincide with the central notch, the spider threads are movedfrom the central notch to the division, and the number of revo-lutions and fractional parts of a revolution which the screwmakes is noted. If now we suppose the value of each divisionof the graduated circle, MN, to be 10, and that ten revolutionsof the screw suffice to carry the spider threads across one of these 36 FIXED POINTS. divisions, then will one revolution of the screw correspond to anarc of 1 ; and if we further suppose that the head of the screwis divided into 60 equal parts, then each division on the headwill correspond to an arc o
Size: 1930px × 1295px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectastrono, bookyear1901
