698 
The most rapid plates are best for this work; 
they should be changed once an hour, and the 
exact times of starting and stopping recorded. 
Care should be taken to stiffen the camera by 
braces, so that the focus will not be changed 
when the instrument is pointed to different por- 
tions of the sky, especially if the lens is heavy. 
If the first method is employed, the position of 
the camera should be changed after each plate, 
so as to include as much as possible of the 
region of the map on each photograph. If 
pointed a little southeast of « Leonis, the ra- 
diant will reach the center of the field about 
the middle of the exposure. A watch of the 
region should also be kept, and the exact time 
of appearance and path of each meteor as 
bright as the Pole Star should be recorded. 
The plates should be numbered on the film side 
with a pencil, and should be sent to the Har- 
vard Observatory with accompanying notes and 
other observations. After measurement there, 
they will be returned if desired. The value of 
the results will be much increased if similar 
photographs can ‘be obtained by a second 
camera from ten to forty miles distant, and 
preferably north or south of the other. 
OBSERVATION OF THE TOTAL SOLAR ECLIPSE 
IN 1900. 
PRESIDENT HARPER, of the University of 
Chicago, at the 30th Convocation of the Uni- 
versity on October 2d, spoke as follows of plans 
for observing the approaching solar eclipse : 
A total eclipse of the sun is regarded as an 
event of great importance by astronomers, be- 
cause of the opportunity it affords for studying 
the solar corona and other phenomena which 
are invisible at other times. The last total 
eclipse visible in the United States occurred on 
July 1, 1889, and a great number of astronomers 
from the various observatories visited California 
for the purpose of making observations. The 
next total eclipse will occur on May 28, 1900, 
the path of the shadow extending through the 
States of Virginia, North Carolina, South Caro- 
lina, Georgia, Alabama, Mississippi and Louisi- 
ana. Extensive preparations for observing it 
are being made by many institutions. General 
arrangements have been entrusted to an Kclipse 
SCIENCE. 
[N. S. Vou. X. No. 254. 
Committee, of which the Director of the Yerkes’ 
Observatory is Secretary, appointed last year, 
at the Harvard Conference of Astronomers and 
Astrophysicists. 
(1) Photographic observations of the spectrum 
of the sun’s edge, similar to those made at the 
recent eclipses in India and Nova Zembla, but 
with more powerful apparatus. 
(2) Photographs of the corona on a large scale, 
for the purpose of showing the detailed struc- 
ture. 
(3) Measurement of the heat radiation of the 
corona. 
This last investigation has not been carried 
out successfully at any previous eclipse. Spe- 
cial instruments have been devised for the pur- 
pose, which promise to give interesting results. 
Professor Nichols, of Dartmouth College, who, 
in the summer of 1898, succeeded for the first 
time in detecting heat radiation from the stars, 
at the Yerkes Observatory, has offered to assist 
in making these measurements and expects to 
furnish part of the apparatus. 
The Yerkes Observatory did not have the 
means to send an expedition to the last eclipse, 
which occurred in India in January, 1898. As 
the present occasion is so favorable, and as the 
expense involved is comparatively small, it is 
hoped that the friends of the observatory will 
make it possible to send out a party. The ex- 
penses will include a large heliostat, with acces- 
sory apparatus for determining the radiation of 
the corona and for photographing the corona 
on a large scale; transportation expenses for 
four astronomers, freight and express charges, 
teaming, lumber, brick, cement, labor, etc. (for 
the construction of temporary shelters for the 
instruments and piers). Other apparatus, in- 
cluding spectroscopes, telescopes, and all mir- 
rors for the heliostat, etc., will be supplied from 
the Yerkes Observatory. The heliostat and 
other instruments to be purchased will become 
an important part of the permanent equipment 
of the observatory, to be used in its daily work 
on the sun. é 
On account of the exceptionally favorable at- 
mospheric conditions which prevail at Lake 
Geneva during the day, special attention is- 
given at the Yerkes Observatory to the study of 
thesun. A number of important advances in our 
