Note 570 — THE THIRD VOYAGE NORTH-WARD TO THE KINGDOMES OF CATHAIA and China, in Anno 1596.
Reading edition
The declination here given (correctly 20° 46′,5) is that of the 24th May; that of the 25th being 20° 57′,6. The amended calculation for both days will be as follows:—
May 24th May 25th.
Observed altitude of sun 34° 46′,0 34° 46′,0
Refraction - 1′,4 - 1′,4
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34° 44′,6 34° 44′,6
Sun’s declination + 20° 46′,5 + 20° 57′,6
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Complement φ 13° 58′,1 13° 47′,0
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φ 76° 1′,9 76° 13′,0
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Or, allowing for the sun’s semi-diameter 75° 45′,9 75° 57′,0
Regarding the several observations of stars as well as of the sun (except those of March 20th, April 2nd and 18th, and May 24th, which are uncertain), as being all equally good, subject only to correction for refraction and amended declination, the result will be 75° 57′,5. Or, assuming that the sun’s lower edge was observed in every case, but not allowed for (and the observations of the stars leave little room for doubting that such must have been the case), and taking the sun’s semi-diameter at 16′, and including also the observations of the two stars, we have 75° 49′,5. In either case the latitude will be rather to the south than to the north of the 76th parallel. But, as all the latter observations of the sun were made under an erroneous impression, and evidently with a desire that they should correspond with what was believed to be the truth, the safest plan will be to content ourselves with the observations of the two stars and the first observation of the sun on February 19th, the result of which will be:—
γ Orionis 75° 43′,0
α Tauri 75° 47′,9
☉ 75° 44′,1
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135
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Which gives exactly 75° 45′ as the latitude of the spot.