The New York herald., 1877-08-25
Method Proposed by Professor Eastman
for Determining the Solar Parallax.
THE DECEITFUL MIRROR.
A Grave Suggestion from Patterson win
Regard 10 Mars Twins.
SHALL THEY BE VAcclNATED ?
rny TELEGRAPH TO THE HERALD. ]
WAsniSGroS, August %, Is

TBY TELEGRAPH TO TIE HERALD.
WASHINGTON, August %, 1877.
The Distance of the first satellite fourteen or 1f.
teen thousand miles from the planet Of Mars. This
brings tho satellite nearer to Mars than any known
satellite to its planet, being about the one-sixtcenth
the distance OF from the EARTH The diameter
OF the new satellite is probably about seventy-Ave
miles 1t is regarded being of tho greatest dis
coyercs Of century and will assist very materially
in the advancement OF science Professor Hall, the
dscoyerer Is an able and learned mathematician
well as a modest but conscientious observer. The
facts this discovery have been teiegraphed to all the
observatories Of the world, and should the weather
rontnus fine new results Will be Obtained and given TO
the scientific world heretofore II has not been poss
ble to ascertain the construction Of the planet
Mars and this discovery will assist very materially
In calculating Its construction BY aid of the great
telescope at the United states Naval Observatory many
discoveries OF great Importance will undoubtedly be
made in tho future. Congress should Immediately
make sufficient appropriations for tho proper care OF
the Naval Observatory instead OF allowing the building
and some instruments 60 to rum for want of
good shelter. No public institution in the United
States is in such a deplorable condition. The money
appropriated for it is not sufficient to keep the
old building warm in winter. Admiral Rodgers was
busily engaged recently at the Navy Yard trying TO
find some old condemned boiler which could be used
to the building of the Observatory, and the future
prospect is either freeze out or borrow some old
wornout stove that Congress may not be troubled
with the proper demands OF the tinted States Naval
Observatory. The Observatory has been sadly
neglected of late years The coming Congress should
let II have an appropriation. Many things OF great
will result from this discovery just now
made. Tho tumble-down building should be repaired,
new fences built that the Naval Observatory
is fast gaming favor let be national institution that
all may be proud Of To that end 1t must be properly
sustained and iostered.
Many congratuatory letters are coming in from the
INHERENT observatories commenting the great good
,ne discovery OF Professor Hall will cause to re-
Iuit to SCIENCE The authorities have been compl-
nented IN tho highest terms for their CONSCIENTIOUS
operations and reports which have been widely
accepted and which by Of their accuracy have
been commended to all scientific persons and instu-
lions. The National Observatory here is now tho
to which popular attention turned and the
nown Of its works and discoveries will bring additional
good standing TO II. The professors want 1t now
made grand In appearance as II Is ascendant in In.
tellect and they say that every American should
loice that they have of the foremost institutions
with the largest telescope in the world The line off,
Of the navy justly proud of this, for among
them, 1t is felt this standard and repue had its BIRTH
THE OPPOSITION OF MARS IN loI|-METHOD
PROPOSED FOR DETERMINING THE SOLAR
PARALI.Ax BY REGULAR OBSERVATIONS OF
THE STARS FROM POINTS NORTH AND SOUTH
OF The EQUATOR.
The following paper by Professor Eastman, of the
United States Navy, tho subject OF the opposition of
Mars in 1877, will be found an interesting addition TO
astronomical literature refers to proposed observa
ions by which the centre of the planet Mars
be determined 1871 and from which the basis Of the
system for measuring the solar paralax can be de-
duced The accompanying tables have reference to the
period between July Is and October Il, 1877.
The determination of the solar parsllax within de-
sirnbe limits oil is still work of the future and
1t bohooves astronomers not TO leave unlried any
method that promises TO yeid valuable aid IN the sou
lion OF this important problem.
The deep and general interest in this problem has
lately been manifested by the liberal grants which
were made by the principal governments OF the world
TO enable astronomers to test thoroughly the value OF
those methods OF depending the observations Of the
transit OF Venus under favorable circumstances.
The opposition OF Mars IN 1877 VIII AFFORD favorable
opportunity for employing observations of this planet
in the determination OF the solar paraax with little
extra expense those governments individuals
already provided with meridian czces In fixed OBJ
servatores
The accuracy with which OF the similar OBJ
servations Mars made in 1852 affords strong
grounds tor the belief better results may be OBJ
Named by this method than have reached by any
method heretofore, and makes II very desirable that
astronomers should make combined effort on suit
In 1877.
In pursuance of this idea venture to propose the
following method OF observing which is given IN de-
tail order that all the observations may po made in
the way, to annex u list OF stars avorably
situated for conn mparson.
This method OF observing with a few exceptions, Is
essentially the same as that proposed by Dr. A. VIM
necke in 1867, and followed by him IN his excellent
observations with the meridian crco at Pulkowa
METHOD or OBSERVING.
!. It Is essential that all the observatories In the
Bouthern Hemisphere which have suitable Instruments
should the OBSERVATIONS, and at least an
equal number north of the Equator
2 In order eliminate all errors depending on the
positions OF the comparison stars, every observer
should every instance observe those stars selected
for the given night and in case depart from this
rule.
3 The observations should commence ON July Is,
continue every favorable night until October 81
With Instruments Of less than six inches aperture
attempt should be made TO observe the transit of
the planet further than note TO the nearest
second the time oil the dissection OF the object unless
II Is made at some vertical wire whose distance from
tho centre of The Held is KNOWN and only one bisec-
ton OF the object should be made, that beng, II pos
sible. near the centre Of the field.
With larger and more stable instruments the right
ascension of the stars and OF the first aud second limbs
OF the planet be observed and at least two Disec
tions made before anu alter the observation
of traDsis at equal OF known distances from the md
die OF the field Unless a chronograph is used
transit observations should be attempted in any
8. The method OF obtaining the position Of tho cen
ire Of Mars propose ed by DR. winnccke In 1862, has
struments that Is desirable that he adopted 1871
Substantially the method is as lollows:-
Two threads OF equal size are inserted in the NOV
able dccnaon system tho .1eId telescope; the dis
tanco between them being three four seconds less
than the minimum diameter OF the planet during the
proposed period of observation. The observation Is
Infected BY moving these threads until the two small
.Jermens of the planets outside of the threads are
seen TO be exactly equal
II the thread nearest the mcrometcr head ie desg-
mated as thread and the other thread then the
comparison stars should be observed by bisectng the
hrs fourth nth and eighth stars with thread a. and
the scoond third sixth and seventh with thread
This order should be reversed on alternate nights,
but IN all the thread used bisecing ought to
De carefully recoi ded for eacn
o. The inclination OF the declnation threads should
he carefully ned ut least durIng the period
from July Is TO October IL
The division errors oil the circles used should be
carefully investigated at least In the vicinity those
division employed IN tho observations.
g. Whenever the microscope threadsare moved moro
than twelve seconds The microscopes should be read
tor each adjacent division.
o. In making the bisections the telescope microme-
Ter should be moved IN all cases toward The spring
against which II acts.