The student's manual of natural philosophy / [Charles Tomlinson].

  • Charles Tomlinson
Date:
1838
Catalogue details

Licence: Public Domain Mark

Credit: The student's manual of natural philosophy / [Charles Tomlinson]. Source: Wellcome Collection.

    609/640 page 599
    MERIDIAN-LINE. that is, the hour angles must he calculated for the inclination of the plate. But supposing a level to be obtained, draw three or four concentric circles from any point near the middle of the Fig. 8. plane n; and at the centre of these circles, set up a perpen¬ dicular object, such as a wire or stick b. This wire must be of such a height, that the top of its shadow shall fall among the circles, for several hours during the middle of the day. In order to attain perpendicularity in the wire, the two legs of a pair of compasses may be applied, one to any one of the circles, and the other to the top of the wire. If such distance remain equal all round, the wire is quite perpendicular. Suppose now that, when
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