Abstract
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The Observing Astronomical Society. Report of Observations made during the period from Aug. 7 to Sept. 6, 1870, inclusive. Solar Phenomena:—Mr. T. G. E. Elger, of Bed-ford, writes: “Observers of solar phenomena have seldom an opportunity of witnessing such a fine outbreak of spots as that which took place during the last fortnight of August. After the disappearance of the large group observed in the S. hemisphere (about July 31), a comparative lull in solar activity ensued, lasting thirteen clays; the spots which appeared during; this interval presents d no remarkable features, and were mostly confined to the S. hemisphere. On the 17th, in the N. hemisphere, a large scattered group was observed, which a few days before had consisted of a congeries of minute specks j on the 18th it was 2' 55* in diameter, and was followed by another group, 2' 26“in length; both these groups diminished very rapidly after the igth. On the 2oth the two largest groups on the disc were nearly central; one of them 36", the other 54", in diameter. Cloudy days intervened between the 2ist and 24th. On the latter date the first indications of the approaching outburst were remarked. At 4h 30Â there were three immense groups in the N, hemisphere, extending from the centre of the disc to the E. limb; the preceding group, which was made up of very light and ill-defined penumbra;, enclosing upwards of sixty separate black spots, measured 3' 10“x i'49". The second group was i' 20“in length, the third was too near the line to be satisfactorily measured. From the 26th to the end of the month the north maculose zone was completely crowded with groups and isolated spots, while the corresponding S. zone contained only punctures and small clusters. The following are the lengths of the three largest groups observed on the 2gth; 3' 6", 2' 26", and i' 57". The spotted zone could be seen with the naked eye, protected by an ordinary dark glass at noon on the 28th; it had the appearance of a dusky belt parallel to the sun's equator. Fresh groups observed in the sun's N. hemisphere during August = n; ditto observed in the sun's S. hempishere = 15. Maximum number of groups on disc 13 (Aug. 29, 2ih l8m); minimum number = 4 (Aug. 20, 4h I5m). Mr. William F. Denning, of Bristol, observed the sun with his 3in. refractor, on Aug. 28, and reports that on this date four large groups of spots were visible in the northern hemisphere. In the N. E. quadrant two large groups were perceptible lying just above the equator. In the N. W. quadrant an irregular scattered group was seen near the limb, and another group near the centre of the disc was very conspicuous. The S.E. quadrant contained three small groups, while the S. W. quadrant was entirely free from visible spots.
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Societies and Academies. Nature 2, 507–508 (1870). https://doi.org/10.1038/002507c0
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DOI: https://doi.org/10.1038/002507c0