Astronomische Nachrichten/Volume 72/Beobachtung der Sonnenfinsterniss am 18. August 1868 zu Windsor in New South Wales

by John Tebbutt

Beobachtung der Sonnenfinsterniss am 18. August 1868 zu Windsor in New South Wales.

The solar eclipse of the 18^th ultimo was pretty well observed here . Although the sun was occasionally hidden from view by passing clouds the beginning and greatest obscuration were well seen. A remarkable phenomenon presented itself about half a minute before the instant of first contact. A dark streak or band became visible for several degrees along that limb of the sun to which the moon was approaching, and after continuing visible for a few seconds vanished. It reappeared, however, for a moment immediately before the contact. The darkness seemed to extend along the narrow interval separating the limbs of the sun and moon, but did not encroach on the solar disc. This phenomenon was so palpable that it served as an excellent warning of the time of contact. A very slight flattering of the sun's limb was also remarked just previous to the contact, but this was quite distinct from the indentation produced by the moon. The sun was shining beautifully clear at the time. The first contact was pretty accurately observed at 4^h6^m30^s1 local mean time, the telescope employed being my 3¼ inch refractor with a power of about 30. During the progress of the eclipse there was a slight boiling of the limbs both of the sun and moon. This, however, was the result of atmospheric causes, and was not so great as I expected from the low altitudes of the objects. With the exception of the slight disturbances from this cause, the sun's cusps were sharp and well defined. A careful scruting satisfied me that not the slightest portion of the moon's limb could be even faintly distinguished beyond the cusps. No remarkable irregularities were observed on the moon's limb. Two very fine spots, each surrounded with an extensive penumbra, and attended with several smaller spots, were very conspicuous on the southern half of the sun's disc, but where not eclipsed by the moon. A magnificent tract of faculae, situated near the larger spot, contrasted very beautifully in colour with the general ground of the solar disc. About one third of the sun's diameter was eclipsed at the time of greatest obscuration. The sun disappeared behind a dense cloud on the horizon at 5^h16^m.

Meteorological observations were taken through the day, but nothing remarkable, beyond the unusual steadiness of the barometer, was recorded. The observations of the blackbulb thermometers were much interfered with by passing clouds.

1868 September 1. John Tebbutt jun.