Lectures on Practical Astronomy and Astronomical Instruments (1879)
Challis, James Rev. · Deighton, Bell and Co. (Cambridge) · leaf 83
ed position. For an alt-azimuth the process would be to adjust nearly the vertical and horizontal axes of motion by spirit-levels, and then determine the meridian direction by equal altitudes of the same star before and after its passage across the meridian. 66. The instrument having been thus put… … field of view, Aa is one of the transit wires, and Dd is the middle wire. Transits are taken at Aa and Dd, after which the instrument is reversed. After the reversion, whereby Aa
Book · Astronomy
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