APRIL 12, 1901.]- 
altogether, and in others it would render use- 
less for nomenclatural purposes much original 
investigation through which genera have been 
definitely established. Unless rigidly restricted 
in such a way as to avoid these defects it would 
be impracticable and undesirable. 
N. L. BRITTON. 
CLAYTON’S ECLIPSE CYCLONE AND THE DIUR- 
NAL CYCLONES. 
Mr. H. H. Crayton, of the Blue Hill 
Meteorological Observatory, Mass., has pub- 
lished an account of his discussion of certain 
meteorological observations made during the 
eclipse of May 28, 1900, in the Proceedings of 
the American Academy of Arts and Sciences, Vol. 
XXXVI., No. 16, January, 1901; and the full 
report in Vol. XLIII., Part 1, of the Ann. 
Har. Coll. Obs’y, 1901. Mr. R. DeC. .Ward 
reviews these papers in SCIENCE of March 1, 
1901, and says, ‘‘Clayton has gone far ahead 
of all previous investigations of the phenomena 
of eclipse meteorology. The low temperature, 
the circulation of winds and the form of the 
pressure curve all proclaim the development 
by the eclipse of a cold-air cyclone, as described 
by Ferrel; * * * The fall of temperature due 
to the occurrence of night must also produce, 
or tend to produce, a cold-air cyclone. Since 
the heat of day produces, or tends to produce, 
a warm-air cyclone; * * * These causes must, 
in the opinion of the author, produce entirely, 
or in part, the well-known double diurnal 
period in air pressure; * * * His explanation 
of the diurnal variation of the barometer seems 
to have in it many evidences of being the best 
yet offered to account for this puzzling phe- 
nomenon.”’ 
I suspect that Mr. Clayton and Mr. Ward 
have an incorrect conception of Ferrel’s cold- 
center cyclone, or else they could hardly have 
written about it the remarks contained in these 
papers. The subject is rather complex, but I 
hope, very briefly, to indicate the leading dis- 
crepancies for the benefit of others who think 
that the problem of the diurnal variation of 
the barometer can be solved along these lines. 
1. Some Minor Errors.—Clayton’s Formula, 
page 8, tan = Aiging)e 
= = (coso) v should be written 
SCIENCE. 
589 
ae Zv. sin 0 
2 v. cos 0 
observed wind, and @ that of the mean or pre- 
vailing wind ; but this function between 9 and o 
is incomplete and it often gives an incorrect re- 
sult. In the diagram the wrong diagonal is 
drawn, and this introduces confusion into the 
exposition of the formulz for determining C, 
used in 6! —@ + 180 + C, where 9'is the azimuth 
of the eclipse wind which is required. As the 
eclipse wind for Washington, Ga., Wadesboro, 
N. C., and Blue Hill were computed by these 
formule, the results must be imperfect. The 
observations were themselves not very satisfac- 
tory, as is inferred from the account of them. 
2. The Cold- Center Cyclone.—Ferrel’s account 
of the cold-center cyclone is found in the Re- 
port of the U. S. Coast Survey, 1877, Appendix 
No. 20, page 187; in the Report of the Chief 
Signal Officer, 1885, Appendix 71, page 257; 
and in other places. Also there are some gen- 
eral remarks on the subject in the International 
Cloud Report, 1898-99, page 615. The ac- 
companying diagrams show the circulation in 
the warm-center and cold-center cyclones, re- 
spectively, and the distributions of pressure 
characteristic of them ; these must serve for fur- 
ther explanations in this place. In order that 
there may be no doubt about Ferrel’s idea of 
the cold-center cyclone, I quote from the Re- 
port of the Chief Signal Officer, page 257, ‘‘ The 
gyrations at the earth’s surface must be in the 
same direction as in the case of ordinary cy- 
clones ; * * * The interchanging motion is from 
the center below and toward it above.’’ Re- 
port of Coast Survey, page 188, ‘‘ The maximum 
barometric pressure is where the gyrations are 
reversed ; * * * The pressure is a minimum at 
the center and a maximum at the edge’’ of the 
cold-center cyclone, at all altitudes, meaning by 
edge the locus where the gyrations reverse 
direction. 
Ferrel illustrates the cold-center cyclone in 
these two reports, also in his popular treatise 
on the winds, pages 246-247, 337-342, by com- 
paring it with the general circulation over a 
hemisphere of the earth, where the poles are 
cold and the tropics warm, and states that the 
circulation is the same in each. That-is, the 
air descends at the pole, flows south and east 
tan , where o is the azimuth of the 
