Virginian-pilot. (Norfolk, Va.) 1898-1911, 1900-04-29
The Four Contacts and How Best to Oh
serve Them Understandings.
The Use of Telescopes Smoked Glass and Opera Classes
The Historic Eclipse of May %, 585 B. C--The First
Recorded Eclpse--Frequency of Ecipses--Why Solar
Eclipses of Greater Interest Than Lunar Eclipses

Through red shade glass the contrast
between these two kinds of light might
be partly lost, but through n neutral
tint or green glass it viii be sufficient
ly apparent. Finally. there is yet an
other indication of second contact. and
that is the seemingly miraculous ap-
pearance of the complete outline of the
moon, round and black. reposing upon
the wonderous radiance of the corona.
THE THIRD CONTACT.
The approach of the third contact
will be heraided by the rapid bright
ening of the chromoSphere at the point
of the moons limb. where the sun IS
about to re-appear. and two or three
seconds later a sudden burst of light
will announce the contact itself and
with it the termination OF totaliiy
This contact may be observed without
any shade glass.
THE FOURTH CONTACT.
The observation of the fourth contact
is Il very simple matter. The segment
cut out of the sun by the retre"''nS
limb of the moon is carefully way1n,d
as it becomes less and less, and tbn tn
slant of It's final disappearance is noted
as the fourth contact. The shade glass
used must be sos dark as TO destroy all
disagreeable glare.
JOINT OBSERVATION.
The party to observe the contracts
should consist of two persons. one of
whom should have q time-picce and
writing materials and the other n tel
escope. With regard to the latter in
strument. It may be remarked that IL
it is a common one-a spy-GlaSs, for
instance-there will probably be no
choice as to its magnifying power; but
IL it belongs to the better class and
has n battery OF eye-pieces, the power
chosen should be equal to 10 or 20 times
the diameter OF the objective in inches
To secure the best results the party
should be entirely alone; above all, not
within hearing of other observing
parties. a minute or so before the en-
pected time of contact the person with
the time-piece will fix his eyes upon
its second hand and begin silently to
count the seconds. while the observer
at the telescope will carefully watch
the sun. Upon the occurrence of con-
tact the observer will cry, Mark" and
the person at the time-piece will imme-
diately write down, first. the second;
then the minute; and finally the hour
Before beginning to observe, care must
be taken to see that when the second
hand points to 60, the minute hand is
eNdCliy over minute marx, ana Ill
observing. If the seconds are near co.
special care will be required to avoid
recording a wrong minute. Practice i'll
calling and noting time previous to the
eclipse will greatly diminish the risk
of such mistakes. y little before to-
tality lantern should be lighted, be-
cause without it there may he diff
Guilty in seeing the hands OF the time
piece at the approach of the third con-
tact.
LUNAR AND SOLAR ECLIPSES.
The study of lunar and solar eclipses
is most interesting one and valuable
alike to the astronomer and historian.
for the records OF the eclipses of an
cient times kept by the learned men of
past ages. enables us to fix historical
dates with certainty by astronomical
computations backward into the past.
The minimum number of eclipses that
can occur in Il year is two, and the
greatest possible number is seven--fve
solar and two lunar eclipses. While
solar gcttpses arc the more numerous,
they are also of more interest as the
lunar eclipseS can be seen from all
points on the hemisphere, while eclpses
OF the sun are visible from compare
lively small portion of the earth's sur
face.