Abstract
THE SOLAR PARALLAX.—M. Puiseux, in a communication to the Academy of Sciences of Paris, discusses the numerous micrometrical measures made during the last transit of Venus by MM. Mouchez and Turquet at St. Paul's, and MM. Fleuriais and Bellanger at Pekin. If these observations had possessed a high degree of precision he considers that they would have furnished a very exact value of the solar parallax, but unfortunately, so far at least as regards the measures at St. Paul's Island, the conditions were extremely unfavourable; indeed in a note which follows M. Puiseux's communication Admiral Mouchez remarks that the equatorials provided for that station had no special appliances for this class of observation, and worse still, “les observations ont été faites exactement au moment du passage du centre d'un violent cyclone, pendant la courte eclaircie qui accompagne la plus grande dépression barométrique.” The instruments in fact were more particularly adapted to proposed observations of contacts, and were very weakly mounted; oscillations were occasioned by the violent wind, so that the practised observers had no confidence in their results. Notwithstand ing these circumstances M. Puiseux has discussed the measures, and from the combination which he regards as the most favourable, where 81 observations that appear affected with considerable errors are rejected, leaving 312 measures for calculation, he deduces for the value of solar parallax 9″.05: the mean value of the corresponding residuals 0″.78, and the extreme residuals — 1″.98 and + 2′.15. Considering that under such disadvantageous conditions the observations accord passably, M. Puiseux thinks there are reasonable grounds to expect that with firmly, mounted instruments micrometrical measures may be obtained at the approaching transit in 1882, which will furnish a pretty exact value of the sun's parallax.
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Our Astronomical Column . Nature 23, 591 (1881). https://doi.org/10.1038/023591a0
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DOI: https://doi.org/10.1038/023591a0