In order to compare the Light of the Sun with that of a Star, Dr.
Wollaston took as an intermediate object of comparison the light of a
candle reflected from a bulb about a quarter of an inch in diameter,
filled with quicksilver; and seen by one eye through a lens of two
inches focus, at the same time that the star on the sun’s image,
_placed at a proper distance_, was viewed by the other eye through a
telescope. The mean of various trials seemed to show that the light
of Sirius is equal to that of the sun seen in a glass bulb 1/10th of
an inch in diameter, at the distance of 210 feet; or that they are in
the proportion of one to ten thousand millions: but as nearly one half
of this light is lost by reflection, the real proportion between the
light from Sirius and the sun is not greater than that of one to twenty
thousand millions.
“THE SUN DARKENED.”
Humboldt selects the following example from historical records as to
the occurrence of a sudden decrease in the light of the Sun:
A.D. 33, the year of the Crucifixion. “Now from the sixth hour
there was darkness over all the land till the ninth hour” (_St.
Matthew_ xxvii. 45). According to _St. Luke_ (xxiii. 45), “the
sun was darkened.” In order to explain and corroborate these
narrations, Eusebius brings forward an eclipse of the sun in the
202d Olympiad, which had been noticed by the chronicler Phlegon
of Tralles (_Ideler_, _Handbuch der Mathem. Chronologie_, Bd. ii.
p. 417). Wurn, however, has shown that the eclipse which occurred
during this Olympiad, and was visible over the whole of Asia
Minor, must have happened as early as the 24th of November 29 A.D.
The day of the Crucifixion corresponded with the Jewish Passover
(_Ideler_, Bd. i. pp. 515-520), on the 14th of the month Nisan, and
the Passover was always celebrated at the time of the _full moon_.
The sun cannot therefore have been darkened for three hours by the
moon. The Jesuit Scheiner thinks the decrease in the light might be
ascribed to the occurrence of large sun-spots.