Columbus and the Method of Lunar Distance

Molander, Arne B.

doi:10.1179/008228892791016061

Cited by 2 publications

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“…In his 1992 paper, Mr Molander asserted that timing of the conjunction is not required by this method, because Columbus somehow utilizes the Moon's daily topocentric motion. 3 But how this datum is utilized, and in fact all details of the longitude determination itself, are entirely obscure.…”

Section: ' Columbus's Methods Of Determining Longitude ' Keith a Pickmentioning

confidence: 99%

‘Columbus's Method of Determining Longitude’

Pickering¹

1997

J. Navigation

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I am pleased to see that, in light of my critical evaluation, Arne B. Molander has reevaluated a number of points in his analysis, and has revised his proposals of Columbus's alleged use of the Moon for determining his longitude. However, it is disappointing that these latest proposals again do not seem to have been thoroughly considered.Since it is clear that Columbus's East–West position fixes are not correlated with visible lunar-planetary conjunctions, Mr Molander's latest hypothesis is that Columbus observed a dark-horizon moonrise or moonset near each conjunction – which usually can be done whether or not the conjunction itself is visible. However, it is entirely unclear how such an observation can be converted into a longitude. Reading attentively, we can glean a few details of this process: only a single observation is required, since some positions are computed within a few hours of the purported observation; and Columbus apparently used the Ephemerides of Johann Miiller, since errors in that ephemeris are alleged to have caused errors in the computed longitude. In his 1992 paper, Mr Molander asserted that timing of the conjunction is not required by this method, because Columbus somehow utilizes the Moon's daily topocentric motion. But how this datum is utilized, and in fact all details of the longitude determination itself, are entirely obscure.

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Section: ' Columbus's Methods Of Determining Longitude ' Keith a Pickmentioning

confidence: 99%

‘Columbus's Method of Determining Longitude’

Pickering¹

1997

J. Navigation

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“…3 The ' theoretical' method proposed by this leading cosmographer was probably the well-known use of occasional lunar eclipses, while the ' practical' one might well have advocated the more frequent BTH horizon geometries. 4…”

Section: Smentioning

confidence: 99%

“…Venus (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). If Columbus used this fine horizon geometry (the voyage's best, although i-$ degrees further from the horizon than predicted by the Ephemerides) to estimate his longitude, he would have erred badly in this vital position fix.…”

Section: CDmentioning

confidence: 99%

“…Strong circumstantial evidence supporting this possibility was published by the author four years ago in a Journal for the History of Discoveries addressed mainly to historians and geographers. 4 Keith A. Pickering brought this navigation issue to the attention of appropriate experts in a critique of my article published in the January issue of the Journal of Navigation. 5 Unfortunately, Pickering's article contained a number of errors and misinterpretations of fact, some of which may have resulted from my ambiguous presentation.…”

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confidence: 99%

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