Public ledger. [volume] (Memphis, Tenn.) 1865-1893, 1883-04-24
The COMING SOLAR ECLIPSE.
Preparations for Observing it-Plans
of the United States kxpedi-
ton on the South Pacific.
Instr umenfs 10 be Used-PrO.
posed Work of the English
and French Expeditions.
oaIlao, Peru, Letter to n. Y. Tribune.

/ York on March z, to observe tn
solar eclipse of May 6, from Carolin,
Island in the South Pacific, arrive,
at this port to day, having made
rapid run aud close connections a
Panama. The United States man-of
war Hartford, which is to receive thu
| party, is ready for sea and will sail OF
March ", expecting to make the pas
sage of $500 miles in about twenty
five days, possibly touching at the
Marquesas Islands. After the eclipse
the Hartford will convey the party t
Honolulu. from which place they will
proceed to San Francisco. The mem,
bers of the expedition are: Prof
E. S. Holden, of Washburn Observa-
tory, Madison, Wis, who is chief Of
the party; Mr.. Q. H. Rockwell, OF
Tarrytown, N. Y, through whose per.
sonal efforts the expedition was
planned; DR.. G. S. Hastings, of John
Hopkins University, Baltimore; Mr..
d. Preston, of the United States
Coast Survey; Ensign s. ]. Brown, Of
the United States Naval Observatory,
and Mr.. W. Upton, of the United
States Signal Service. Two English
scientific gentlemen, Messrs. H. A.
Lawranee and .. Ray Woods, OF
South Kensington, joined the party at
Panama. The American expedition
was planned by the National Academy
of Sciences, and is under the charge
of committee Of which Prof, y. A.
Young, Of Princeton, is chairman,
and Prot. J. II. G. Coffin, of Wash
iDgton, secretary. The English mem
bers are sent by the Royal Society and
the Committee on Solar Physic espe-
cially to do Photographic WORK. They
are engaged in spectrosoopio work
with Mr.. Lockyer and were both
members Of the English expedition
which observed the eclipse of last
May at SOhag, upper Egypt,
The programme Of work planned
for the eclipse embraces a variety of
observations, chief of which are these
with the spectroscope. The instru-
mental outfit is large, that of the
American members being contained
in sixty.two boxes, and that of the
English members in twenty-eight, the
majority of them containing apparatus,
but a few devoted to the requirements
of camp life upon the island. There
are seven telescopes mounted equato-
rally, having apertures respectively
of st, 6, 4l-10, 4, 81 and two of q
inches diameter. The Ct inch equa-
torial is provided with grating spec
troscope to be used in examination Of
the chromosphere, before aDd after
totality,and during the total phase the
| grating will be exchanged for large
prism for the study of the corona.
The 6 inch will be used by Prof.
Holden to search for intramercurial
planets, as was done by Prof. Watson
and others in 1868, the results being
not decisive. The 4 lilo inch is pro
vided with grating spectroscope, and
is to be used in studying the relative
length Of lines reversed just before
totality, within a small region of the
spectrum. The grating can be ex-
changed for single co. prism with
which to study the limits to which
the line l474 K can be traced. One
of the 1t inch telescopes is provided
with large 30' prism of flint glass
placed before the objective, and is de-
signed for observing the relative
heights and brightness of certain
spectrum rings. A simple migrating
spectroscope unattached to telescope
will also be used for observing the
lines visible during totally. OF the
other telescopes, one is furnished with
a Savart pOlariscope, designed to
show the character of the coronal
polarization, and the others will be
available for observing the times of
contact and for studies of the shape
and structure of the corona.
The plans of the English members
embrace an extensive series of specs
troscoplc and Photographic work com
bined. A beam Of light will be
thrown by a siderostat upon four
spectroscopes-integrating, Analysing
and prismatic spectroscopes and a
Rowland grating. The plate of the
first named will be driven by clock
work, in the hope that as the portion
illuminated at any one instant is
small, the integrated effects that have
been previously observed may be diff
ferentiated. The Rowland grating is
provided with two cameras, each to be
used upon different portions of the
spectrum. The analyzing and pris.
matte spectrosoopes were used with
success at the Egypt eclipse.
The United States Coast Survey
improves the opportunity to make
pendulum observations at the island,
and also at the Sandwich Islands and
San Francisco on the return. 1t is by
observation with a pendulum made al
different portions Of the earth that
the problem of the true shape of the
planet is shown in the most refined
way.
One other expedition to observe the
coming eclipse is to be located in the
South Pacific. 1t is under French
auspices and includes among its mum
Der the physist NJ. Jansen. Thil
party is to journey to the isthmus a
Panama and from that poin
be conveyed by the man
ot-war LEclaireur. Their destina
ton is also Caroline Island
but it is probable that either the
American or French party will locat,
at Flint Island, which is also in the
path OF totality, in order that boil
islands may be occupied. In the even
OF cloudy weather at one station, tn,
other might be favored with clea
weather. The eclipse is one of lon
, totality, the duration Of the total phas
being between five and six minutes
the greatest duration possible, whel
| fha ofrt, nnI $780,. $50 r 4 4