May 10, 1901.] 
To make the investigation exhaustive, an 
earnest appeal is herewith made to all persons 
who have instruments at their disposal to par- 
ticipate in the proposed observations and to 
put themselves in communication with the 
Division of Terrestrial Magnetism, U. S. Coast 
and Geodetic Survey, Washington, D. C., so 
that the necessary directions may be given 
them. 
The scheme of work proposed embraces the 
following : 
1. Simultaneous magnetic observations of 
any or all of the elements, according to instru- 
ments at the observer’s disposal, every minute 
from May 17, 14h. to 21 h., Greenwich mean 
astronomical time.* 
[To insure the highest degree of accuracy 
attainable, the observer should begin work 
early enough to have everything in complete 
readiness in proper time.}] 
2. At magnetic observatories all necessary 
precautions should be taken, so that the self- 
recording instruments will be in good opera- 
tion, not only during the proposed interval, 
but also for some time before and after, and 
eye-readings should be taken in addition, wher- 
ever circumstances will permit. 
3. Such meteorological observations as are 
possible for the observer should be made at con- 
venient periods (as short as possible) through- 
out theinterval. It is suggested that tempera- 
tures, e. g., be read every fifth minute (directly 
after the magnetic reading for that minute). 
4. Observations of atmospheric electricity 
and of earth currents should be made wherever 
possible, and any other phenomena of impor- 
tance should be fully noted. 
The request is made that observers send, as 
soon as possible, a full report of their work to 
the Superintendent of the Coast and Geodetic 
Survey. 
L. A. BAUER. 
*For America this interval occurs during the night 
hours of May 17th and 18th, civil dates, while for 
Europe, Asia, Africa and Australia, it occurs during 
the morning or afternoon hours (according to longi- _ 
tude of station) on May 18th, civil date. 
{See directions followed by the Coast and Geodetic 
Survey during the recent eclipse, Journal ‘Terres- 
trial Magnetism,’ Vol. V., p. 143. 
SCIENCE. 
747 
CLAYTON’S ECLIPSE CYCLONE AND THE 
DIURNAL CYCLONES. 
In a letter with the above title, in ScIENCE of 
April 12th (N.S., Vol. XIII., p. 589), Professor 
Bigelow criticizes my papers on the ‘ Helipse Cy- 
clone and the Diurnal Cyclones.’ His criticism 
is subdivided into two heads: (1) concerning 
“some minor errors’ which he thinks he finds 
in the formulas, and (2) concerning the theory 
of the cold-center cyclone. 
My method of treating the winds observed 
during the eclipse was first to find the mean 
wind during the eclipse at each station, then to 
find the deflections of the observed wind from 
this mean at intervals during the eclipse, in 
order to see if there were any systematic 
changes which might reasonably be attributed 
to the eclipse. In getting the mean wind, I 
plotted the individual observations of direction 
and velocity, taking them as nearly as possible 
at regular intervals, and drew the resultant di- 
rection for each station. As a check on this 
method and for greater exactness I next com- 
puted the mean wind for stations where the 
wind directions were recorded to degrees of 
azimuth, or the observations were otherwise 
considered sufficiently accurate. Observations 
to only eight points of the compass are not in 
general sufficiently accurate to show the eclipse 
wind. The general winds were from the south- 
west near the central path of the eclipse of May 
28, 1900, in our Southern States, and the obser- 
vations with which I had to deal were some. 
thing like the following : 
Direction in degrees. Velocity in miles. 
(1) S. 23° W. 3 
(2) S. 56° W. 2 
(3) S. 80° W. 1 
These were plotted as shown in diagram 1 A, 
in which the continuous arrows are the observed — 
winds and the broken arrow is the mean wind. 
With the above values the plotted mean was 
found to be S. 44° W. Calling the observed 
wind o and its velocity v, the mean was then 
computed as follows: 
sin. o cos.o (sin. o)v (cos. 0)v 
(1) .391 921 1.173 2.763 
(2) .829 559 1.658 1.118 
(8) .985 174 -985 174 
Sum. 3.816 4.055 
