AMERICAN 
JOURNAL OF SCIENCE AND ARTS. 
[THIRD SERIES.] 
* 
Art. L—Contributions to Meteorology, being results derived from 
an examination of the Observations of the United States Signal 
Service, and from other sources; by Ex1as Loomts, Professor 
of Natural Philosophy in Yale College. Eighth paper. 
With plates I and Il. 
[Read before the National Academy of Sciences, New York, October 24, 1877.] 
The origin and development of storms. 
In order to determine the circumstances under which storms 
originate, and ultimately acquire their full intensity, I selected 
from the published volumes of the Signal Service observations 
(September, 1872, to May, 1874), all those cases in which the 
barometer fell below 29°25 inches at any station. It was found 
that the barometer on Mt. Washington was frequently very 
much lower than at the neighboring stations, Burlington and 
Portland, indicating some peculiarity of this station. 
these cases were therefore set aside, and reserved for separate 
examination. During the entire period under discussion, the 
mean height of the barometer at Virginia City was nearly a 
third of an inch lower than at the neighboring stations, and 
these observations were therefore eliminated from my list. 
There remained one hundred and forty-eight cases in which 
the barometer fell below 29-25 inches at some one of the other 
stations. Sometimes at the same hour the barometer was 
below 29-25 inches at a considerable number of stations all 
included within the same low area. In such cases only one of 
the stations is included in the table, viz., the station at which 
the barometer was lowest. These one hundred and forty-eight 
cases correspond to forty-four different storms, and are shown 
in the following table, in which column Ist shows the number 
of the storm; column 2d shows the date at which the barome- 
ter was below 29:25 inches; column 3d shows the least height. 
of the barometer observed at that hour; column 4th shows the 
Am. Jour. ee Serres, Vou. XV, No. 85.—Jan., 1878. 
