Science in Short ChaptersWilliams, W. Mattieu (William Mattieu)
Science
Science in Short Chapters
Williams, W. Mattieu (William Mattieu)
Science
If, however, this body of glare could be screened off, and only a line
of the sun’s edge, less than one thousandth of his diameter, remain
visible, the notch would appear as a distinct break in this curved line
of light. If a group of spots, or a great irregular spot with several
umbræ, were at such a time situated upon the sun’s edge, the appearance
of a series of such notches or breaks leaving intermediate detachments
of the visible ring of the photosphere would be the necessary result,
and thus would be presented exactly the appearance described as
“Baily’s beads.”
I have been led to anticipate a display of these beads during the
late eclipse by the fact that some days preceding it a fine group of
spots—visible to the naked eye through a London fog—were traveling
towards the eastern edge of the sun, and should have reached the limb
at about the time of the eclipse. The beads were observed by the Rev.
S. J. Perry just where I expected them to appear. I have not yet learnt
on which side of the sun they were observed and photographed by Lord
Lindsay.
Baily’s first observation of the beads was made during the annular
eclipse of May 15, 1836. That year, like 1870, was remarkable for a
great display of sun-spots. As in 1870, they were then visible to the
naked eye. I well remember my own boyish excitement when, a few weeks
before the eclipse of 1836, I discovered a spot upon the reddened face
of the setting sun—a thing I had read about, and supposed that only
great astronomers were privileged to see. The richness of this sun-spot
period is strongly impressed on my memory by the fact that I continued
painfully watching the dazzling sun, literally “watching and weeping,”
up to the Sunday of the eclipse, on which day also I saw a large spot
through my bit of smoked glass.
The previous records of these appearances of fracture of the thin line
of light are those of Halley, in his memoir on the total eclipse of
1715, and Maclauren’s on that of 1737. Both of these correspond to
great spot periods; the intervals between 1715, 1737, 1836, and 1870
are all divisible by eleven. The observed period of sun-spot occurrence
is eleven years and a small fraction.
I am anxiously awaiting the arrival of Lord Lindsay’s long-exposure
photographs of the corona, for if they represent the varying degrees of
splendor of this solar appendage, the explanations offered in Chapter
xii. of my essay on “The Fuel of the Sun” will be very severely tested
by them.
Yours respectfully,
W. MATTIEU WILLIAMS.
Woodside Green, Croydon, January 4, 1871.
THE COLORING OF GREEN TEA.
The following is a copy of my report to the _Grocer_ on a sample of the
ingredients actually used by the Chinese for coloring of tea, which
sample was sent to the _Grocer_ office by a reliable correspondent
at Shanghai (November, 1873). I reprint it because the subject has a
general interest and is commonly misunderstood:
Public-domain text, read in full here on John Shaqi.
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