Virginian-pilot. (Norfolk, Va.) 1898-1911, 1900-04-29


it is Il curious coincidence that one of
the most famous eclipses of his
tory was that on May IS, 5S5, B. c.
This was predicted by Thales, one of
the seven sages of Greece, and it put a
sudden stop to the war between the
Modes and the Lydians. So great was
the awe caused by the sudden cessation
of the light OF the sun that the con-
tending hosts threw down their arms
and made peace.
FIRST RECORDED ECLIPSE.
The first eclipse of which record is
preserved was an eclipse of the sun
212S &. c. In 2169 b. C. the Emperor
of China put the chief astronomers. Ho
and Hi. to death for falling to announce
the Solar eclipse OF that year. The
ChaldeanS were famous astronomers,
and when Alexander the Great took
Babylon in SS1 Il. c. he found records
of their observations covering the pre-
vious nineteen centuries.
Eclipses are repeated at regular in
terval of IS years and IL Ia days.
Therefore, after the lapse of this pc
Rod, this great eclipse of May 2Sth will
be repeated, but it's track will be about
100 degrees further TO the West. The
Chaldeans and other enlightened Deo-
pie of ancient days used this period III
foretelling cclipses.
MAKING OBSERVATIONS.
A proper telescope for observation
of the eclipse is very desirable, but any
telescope at all is better than none; and
owners of small spy glasses, or opera
glasses, should bear in mind that their
instruments are capable Of doing good
service. Opera glasses can be held In
the hand with sufficient steadlneSs, but
spy-glasses, however small, will require
stand TO produce the best effect. This
need not be an elaborate affair, but
may be made of wood in the simplest
manner, provided only that it is capa-
BILE of holding the telescope steadily In
any required direction. Some artificial
support is necessary, and, in default of
anything better. the telescope might
even be dashed TO round post.
SHADE GLASSES.
For the first and last contact shade
glasses will be necessary. The best
form is undoubtedly a long wedge of
colored glass. achromatized by n sim
liar wedge of white glass firmly &C.
mented to 1t. The most usual, and by
far the most Objectionable color for
n shade is red. Either a neutral tint or
green is excellent, but it is difficult to
obtain the latter sufficiently dark.
while deep blue has been advocated by
some observers. When no proper shade
is at hand an excellent substitute can
be made by smoking n slip of thin fiat
glass, about an inch wide and inches
long, in such way that its tint may
increase uniformly from very light at
one end to q depth at the other end sur
ficient for viewing the brightest sun
without inconvenience. The smoked
surface should be protected by n cover
ing glass, of the same size as the orig
inal slip. and separated from 1t by bits
of thin cardboard. inserted at the
ends, the whole being bound together
by narrow strip of paper pasted
around the edges. For observing the
second contact of the eclipse. neutral
tint, or green, spectacle glass will be
found convenient.
-9f course It Will be understood that
the necessity for caps to diminish the
aperture is confined to common tele-
scopes. Instruments intended for OBJ
serving the sun are always provided
with arrangements for getting rid Of
the excessive light and heat without dI-
minishing the aperture, and often with
out using shades.
THE FOUR CONTACTS.
In regard to the four contacts the
Virginian- Pilot has heretofore spoke
briefly regarding them. but we will now
consider them more fully in order that
they may be easily distinguished by the
ordinary observer.
THE FIRST CONTACT.
There is generally some uncertainty
about the first contact, because the
slight ndentntion in the SUMS limb,
which, unless the observer knows pre-
ciseiy where to look for it, naturally
attains some size before 1t is seen. and
thus the contact is noted too late. If
the telescope has positions micrometer
it's wire may be set at the compiled
point OF first contact, and then there
will be no difficulty; but In the absence
of such an arrangement, the only way
is to use power of not more than 80
diameters, and to watch carefully
portion of the suns circumference large
enough to include with certainty the
point in question. The shade glass
employed should be sufficiently dark to
destroy all glare, and to permit of the
suns image being viewed without eff
fort.
THE SECOND CONTACT.
The internal contacts. or beginning
and end of totality are phenomena of
such a definite character that the in
stants OF their occurrence can De noted
within a small fraction of second.
For n minute or two before the pre-
dicted time of second contact the suns
thin. and now fast waning crescent,
should be carefully watched through a
neutral tint or green shade glass as
light as the eye can conveniently bear.