DIY History | Transcribe | Scholarship at Iowa | Eccentricity of the Sextant by Frederic Furbish, 1893 | Eccentricity of the Sextant by Frederic Furbish, 1893, Page 73

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Eccentricity of the Sextant by Frederic Furbish, 1893

Eccentricity of the Sextant by Frederic Furbish, 1893, Page 73

[page]66[/page]

over the entire arc of the instrument.
     3. The method of determining the eccentricity employed in this work was an original one devised by Prof. L. G. Weld of the University and used here for the first time.
     It is a form of class (c) or that in which the eccentricity is found by measuring the altitudes of known stars.
     The following diagram and solution is perhaps the only explanation of the method necessary as the work is carefully and clearly developed step by step.
     Let, P = the eccentricity 
             i = index error
             l = length of index arm
             θ = angle of eccentricity
             ∝[subscript]0[/subscript]' = reading of arc
             ∝' = ∝[subscript]0[/subscript]' + i = reading corrected for index error
              ε = correction for eccentricity.

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[page]66[/page] over the entire arc of the instrument. 3. The method of determining the eccentricity employed in this work was an original one devised by Prof. L. G. Weld of the University and used here for the first time. It is a form of class (c) or that in which the eccentricity is found by measuring the altitudes of known stars. The following diagram and solution is perhaps the only explanation of the method necessary as the work is carefully and clearly developed step by step. Let, P = the eccentricity i = index error l = length of index arm θ = angle of eccentricity ∝[subscript]0[/subscript]' = reading of arc ∝' = ∝[subscript]0[/subscript]' + i = reading corrected for index error ε = correction for eccentricity.