Evening star. [volume] (Washington, D.C.) 1854-1972, 1892-10-17


only O.sOS OF Tho suns diameter the principal
observations 20 be made upon IL will consist il
determining the exact times Of the first and
last contacts. For that purpose the Necessary
instruments viii be telercOpe provided with
eolored shade glasses and good watch oil
chronometer
A telescope of at least three inches cleal
aperture Is preferable. but even a small spy
siass may DO good service II mounted upon
stand. This need not be an elaborate affair
but may be made Of wood in the simplest man
ner. provided only that II Is capable Of holding
ne telescope steadily pointed In any required
direction. some srtifcial support is absolutely
necessary. and IN default 81 anything better the
telescope NAV even be lashsd 10 n round post
now To PREPARE THE TELESCOPE.
when the eyePieces OF q telescope are not
provided with proper sun shades an excellent
substitute can be made By smoking slip Of thin
fat glass about one inch vide and four inchs.
long. In such w.y that its tint may increase
uniformly from very hight At one end 20 a depth
81 the other end sufficient for viewing the
brightest sun without Inconvenience. The
smoked surface should be protected by q Gov
eriEg glass Of the size the original slip,
and separated from IL BY bits Of this card in
serted At the ends. the whole being bound to-
gsther BY narrow strip Of paper pasted around
the edges.
The hrst touch Of the moon upon the sun
limb l. technically called the frat contact. and
the suns dick marks the last contact.
There IL generally some uncertainty about the
first contact. because the only evidence OF its
occurrence Il a slight indentation In the sun .
LIMB, which. unless the observer knows pre-
ci-elv where to look for It, naturally sttains
some size before IL i Seen and thus the contact
& noted too late. IL the telescope has a posi-
ton uGicrome ter its wire may be set ut the COM
Iuted point Of first contact. and then there will
h no difficulty. but IN the absence Of such an
-
not more than sixty diamcter-, and 10 watch
carefully portion Of the suns circumference
hrgs enough To include with certainty the
POINT In question. The shade glass employed
should be sufficiently dark 20 destroy all glare
and 20 permit Of the suns image being vie we'd
without effort.
The observation Of the last contact is a very
simple matter. The segment cut out of the
sun by the re-resting limb o.: tine moon is care
fully watched 49, u becomes less and less and
TIE instant Of Its final disappearance Is noted
- the last contact
sELECrING An OBSERVATION STATION.
To observe the contacts a station must be
chosen where there is an uninterrupted view
OF the sun. and the party must consist Of ouiy
two persons one Of whom must have time
piece and writing materials and the other MIST
have a telescope With regard to the latter in
strurnent IL may be remarked that il it is a COM
mon one-a spy glass. for instance-there viii
probably be no choice to Its Inagnifying
poSeT. but IL 1t belongs TO the better class and
has a battery OF eye pieces the power chosen
saOuId be equal TO fifteen or twenty times the
Iameter Of the objective in inches. To secure
N. hest results the party must be entirely
alone, and, above all. it must not be within
hearing OF other pa-ties A minute or so be-
fore the expected time of contact the per-
fon with the timspiece will fix his
eyes upon tts second hand and begin
silently To count the seconds, while the OBJ
server at the telescope will carefully watch the
sun Upon the occurrence Of contact the
observer will cry mark, and the person at the
timepiece will Immediately write down, first
the second; then the minute. and finally the
hour. Before beginning 10 observe. care mus,
be taken TO see that when the second hand
points 10 90 the minute hand is exactly over
minute marx: and in ob.eryingif the seconds
are near 30 special care will be required to
avoid recording a wrong minute. For eI-
ample, when the time j. Sra SIS. the minute
hand will be almost exactly over AM. and
special care must be taken not to record Am
bss. instead Of 3m. So. Practice in calling and
noting time previous 20 the eclipse will greatly
diminish the rizk OF such mistakes.
CALrULArISa THE TIME
The error of the timepiece on standard time
must be accurately known. and in most cases it
can be readily obtained from the tclegraphic time
signals. which are received daily at nearly every
railroad station in The country The intending
observer can best utilize these signals BY max
fng SURF that the minute and second hands Of
hi watch agree With each other. As explained
above. and then carving the watch to the tele-
graph Office on October l9. 20 and a. and noting
The hour. minute and second indicated by it
when the signal j. received. No matter how
the watch NAV run il must not he meddled with
IN any way. either by moving it, hands or
touching it, regulator. between October le and
October 81 without this precsution neither
it, rate nor the degree OF dependence to be
placed upon it can be determined.
The Anal record Of a set OF observations
shouid contain the following information:
l. The rAme Of the staten, including town.
county and state.
q The date.
5. A description Of the location Of the station
with reference To- the nearest prominent land
mark. az. for eIsmp!~, rs bearing and distance
Il, m the n.srestcourt house. railroad station or
church or it, po-iuon with respect to the lines
OF the United States land survevr: or the bear
Ing and distance % prominent mountain peal; :
or The bearing Of three OF more such mountain
Ieas.. OF. In the case 81 city. the street and
number. together with the names Of the nearest
cross streets on each side.
4 description Of the timepIece and state
rnent - the aperture. focal length and mag
nifying power % the telescope employed
5. The times Indicated BY the watch at the
reception Of the Geographic time signals on
October 10 20 and 81.
6. The time O, each OF the contacts Inst as
read from the face Of the watch without the
application % any correction whatever.
!. Ar estimate Of the uncertainty to which
thee unles are liable.
= Any remarks which NAV be thought neces-
sary.
.. The signatures Of the two Observers thus.
A. b., observer with telescope: {. d.. time OBJ
server.
IL several parties observe the eclipse In the
same neighborhood IL Is quite likely that their
recorded time- NAV differ a little. Such Differ
enees occur even IN the work OF the most prac-
rced astronOmer- and they must be allowed to
remain. IL l. never permissible to alter the
record mere suspicion that such a thing
ha- been done will insure the entire REJECTION
Of the observation
Carefully made observations Of the contacts
vii be valuable for correcting the lunar tables.
and II recorded In the form described above
AID mailed 20 the superintendent Of the United
States naval observatory. Washington. %. G..
they will be gladly received and properly util,
fred
New Works. sympathy for Mr.. Breckinridge.
The New York state worlds fair board
has given out the following: The New
York board Of general managers. mortified
st the treatment of Congressman Breckin-
ridge bv the Chicago press, have er-
tended him cordial invitation TO attend the
exercise. Of the dedication Of their state build
ing NJ Chicago on Saturday, October %. and