Notes shewing how to get the angle of parallax of a comet or other phænomenon at two observations to be taken in any one station or place of the earth and thereby the distance from the earth / by R. Holland.
About this Item
Title
Notes shewing how to get the angle of parallax of a comet or other phænomenon at two observations to be taken in any one station or place of the earth and thereby the distance from the earth / by R. Holland.
Author
Holland, R. (Richard), 1596-1677.
Publication
Oxford :: Printed by L. Lichfield for Richard Davis,
1668.
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Subject terms
Parallax.
Astronomy -- Early works to 1800.
Cite this Item
"Notes shewing how to get the angle of parallax of a comet or other phænomenon at two observations to be taken in any one station or place of the earth and thereby the distance from the earth / by R. Holland." In the digital collection Early English Books Online 2. https://name.umdl.umich.edu/A44164.0001.001. University of Michigan Library Digital Collections. Accessed May 8, 2024.
Pages
But if the Difference of Two Parallaxes be given.
IX. Then seeing the sines of the Distances from the Zenith of the Start, is the termes of Proportion between the two unknown Parallaxes thereof, as by he 7th. Note, thereforee take the natural sines of the said distances, and subtract the lesser sine from the great∣er, and take half the difference for the First in the Rule of Three; also adde the same half difference to the lesser sine of distance from the Zenith, for the Third in the Rule of Three, and then the Proportion is,
As the half difference of the Two sines from the Zenith, To the Tangent of the half difference of the Parallaxes, So is the Aggregate of the half differ∣rence
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of the sines aforesaid, and the lesser sine of distance from the Zenith, To the Tangent of an other Arch.
To which Arch adde half the differ∣ence of Parallaxes, it giveth the great∣er Arch of Parallax; But the half dif∣ference of Parallax subtracted from the same Arch leaveth the lesser Arch of Parallax. See Clavius's 7th. Prop. of his Triangula Rectilinea.
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