AMERICAN JOURNAL OF SCIENCE. 
[THIRD SERIES.] 
Art. I.—Controbutions to Meteorology, being resulis derived from 
an examination of the observations of the United States Signal 
Service and from other sources; by Ex1as Loomis, Professor 
of Natural Philosophy in Yale College. Thirteenth paper, 
with two plates. 
[Read before the National Academy of Sciences, Washington, April 20, 1880.] 
Great and sudden changes of temperature. 
_ In my third paper (this Journal, vol. x, p. 10,) I called atten- 
tion to the great and sudden changes of temperature which fre- 
quently occur in some parts of the United States, and noticed 
a very remarkable case which occurred at Denver, Colorado, 
in January, 1875. As the observations for this month at all 
the stations of the Signal Service have now been published, I 
ropose to examine this case more particularly, and also to 
resent some additional facts connected with the same subject. 
y third paper contains two tables, showing for each station of 
the Signal Service for the years 1873 and 1874, the number of 
cases in which the difference between the maximum and mini- 
mum temperatures of the same day amounted to at least 40°. 
I have extended this comparison to the four years of observa- 
tions since published in the Annual Reports, and find 118 sta- 
tions at which at least one such case was reported. As the 
table is too large to be published entire, I have retained only 
those stations at which the average number of cases amounted 
to at least six annually. The following table exhibits these 
stations arranged in the order of frequency of great changes 
of temperature. Column first shows the names of the sta- 
tions ; column second their latitude; column third their longi- 
Am. Jour. 6 Ble Series, Vou, XX, No. 115.—Juuy, 1880. 
