DIY History | Transcribe | Scholarship at Iowa | Theory of the astronomical transit instrument applied to the portable transit instrument Wuerdemann no.26: a compilation from various authorities, with original observations by Harry Edward Burton, 1903 | Theory of the astronomical transit instrument applied to the portable transit instrument Wuerdemann no. 26: a compilation from various authorities, with original observations by Harry Edward Burton, 1903, Page 87

Theory of the astronomical transit instrument applied to the portable transit instrument Wuerdemann no. 26: a compilation from various authorities, with original observations by Harry Edward Burton, 1903, Page 87

Wire Intervals
The number of seconds required for a star to pass from a side wire to the middle wire varies with the declination of the star, being least at the equator and increasing as δ numerically increases. The number of seconds required for a star of declination δ to pass from a side wire to the middle wire is their wire interval for that declination and may be denoted by I[subscript]δ[/subscript][superscript]s[/superscript]. The number of seconds required for a star on the equator to pass from a side wire to the middle wire is called the equatorial interval of the two wires and may be denoted by I[subscript]0[/subscript][superscript]s[/superscript].
The wire interval I[subscript]δ[/subscript][superscript]s[/superscript] may be computed when we know I[subscript]0[/subscript][superscript]s[/superscript] and the equatorial intervals for the different wires may be computed from observations which furnish wire intervals for different declinations.
We shall proceed to find a relation between I[subscript]δ[/subscript] and I[subscript]0[/subscript].

Wire Intervals
The number of seconds required for a star to pass from a side wire to the middle wire varies with the declination of the star, being least at the equator and increasing as δ numerically increases. The number of seconds required for a star of declination δ to pass from a side wire to the middle wire is their wire interval for that declination and may be denoted by I[subscript]δ[/subscript][superscript]s[/superscript]. The number of seconds required for a star on the equator to pass from a side wire to the middle wire is called the equatorial interval of the two wires and may be denoted by I[subscript]0[/subscript][superscript]s[/superscript].
The wire interval I[subscript]δ[/subscript][superscript]s[/superscript] may be computed when we know I[subscript]0[/subscript][superscript]s[/superscript] and the equatorial intervals for the different wires may be computed from observations which furnish wire intervals for different declinations.
We shall proceed to find a relation between I[subscript]δ[/subscript] and I[subscript]0[/subscript].