DIY History | Transcribe | Scholarship at Iowa | Eccentricity of the Sextant by Frederic Furbish, 1893 | Eccentricity of the Sextant by Frederic Furbish, 1893, Page 94

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Eccentricity of the Sextant by Frederic Furbish, 1893

Eccentricity of the Sextant by Frederic Furbish, 1893, Page 94

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     In table VIII A interpolate to the nearest 1/4 second. In most cases the interpolation may be performed mentally.
     After recording the number and logarithm under the heading IV we proceed with the next step, - determining the values of A and B. A, as was shown in the formula, is ((cos φ cos δ)/(sin(φ -  δ))), and B, ((cos φ cos δ)/(sin(φ -  δ)))[superscript]2[/superscript] cos (φ -  δ). φ is the latitude = 41°40'15" ; δ is taken from the Nautical Almanac = -10°36'23.1s , φ - δ = 52°16'38.1". Turning to a logarithmic table or find log cos φ = 9.873307 log cos δ = 9.992516(n), log sin(φ - δ) = 9.898166 log cot(φ - δ) = 9.888474.
     Performing the indicated work.-     
log cos φ = 9.873307   
log A[superscript]2[/superscript] = 9.935314
log cos δ = [underlined]9.992516[/underlined](n)
log cot (φ - δ)[underlined]9.888474[/underlined]
log cos φ cos δ = 9.865823(n)
log B 9.823788
log sin (φ - δ) = 9.898166
log A[superscript]2[/superscript] = 9.935314
log A = 9.967657(n)

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[page][illegible][/page] In table VIII A interpolate to the nearest 1/4 second. In most cases the interpolation may be performed mentally. After recording the number and logarithm under the heading IV we proceed with the next step, - determining the values of A and B. A, as was shown in the formula, is ((cos φ cos δ)/(sin(φ - δ))), and B, ((cos φ cos δ)/(sin(φ - δ)))[superscript]2[/superscript] cos (φ - δ). φ is the latitude = 41°40'15" ; δ is taken from the Nautical Almanac = -10°36'23.1s , φ - δ = 52°16'38.1". Turning to a logarithmic table or find log cos φ = 9.873307 log cos δ = 9.992516(n), log sin(φ - δ) = 9.898166 log cot(φ - δ) = 9.888474. Performing the indicated work.- log cos φ = 9.873307 log A[superscript]2[/superscript] = 9.935314 log cos δ = [underlined]9.992516[/underlined](n) log cot (φ - δ)[underlined]9.888474[/underlined] log cos φ cos δ = 9.865823(n) log B 9.823788 log sin (φ - δ) = 9.898166 log A[superscript]2[/superscript] = 9.935314 log A = 9.967657(n)