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AMERICAN JOURNAL OF SCIENCE. 
[THIRD SERIES.] 
Art. XIII.—Coniributions to Meteorology; by Eutas Loomis, 
Professor of Natural Philosophy in Yale College. Twentieth 
paper. 
[Continued from page 17.] 
Reduction of Barometric observations to sea-level. 
I next proceeded to make a similar comparison of the obser- 
vations at Summit station and Sacramento in California. 
hese ya ean which are in manuscript, were again loaned 
me by Prof. J. D. Whitney. Table Tt sho ws the principal 
batbineabs minima at Summit during a paisa of three years, 
and table IX shows the principal barometric maxima at Sum- 
mit during the same perio e hours of observation were 
7 A. M., 2 and 9 Pp. M. and these hours are n indicated by the num- 
erals he 2 and 3. 7 
e numbers in each of these tables were arranged in the 
order of the mean temperatures, and divided into four equal 
SHU and the average of the numbers in each group was 
en. The results are given in the first five columns of table 
IIL and the numbers in the following columns were computed 
in the manner already explained for Mt. Washington. These 
results for barometric minima accord well with those for Pike’s 
Peak; but for barometric maxima the differerices between the 
observed reductions from Summit to Sacramento, and those com- 
puted by Ferrel’s formula, are three times as great as for Mt. 
Washington, and more than twice as great as for Pike’s Peak. — 
A Basics of this difference is unquestionably due to an ies 
_ In the assumed mean temperature of the air column. 
This is 
shown by the observations at Colfax. For the Onltfoeita 
Meteorological observations, Prof. Whitney selected thrée sta- 
tions, Sacramento, Colfax and Summit ; the at station being 
elevated 31 feet above sea- level; the second feet and the 
third 7017 feet. These three stations are saa in a straight 
line, and Colfax is nearly a from the other two sta- 
tions. The table at the bottom of the next page shows the _ 
mean temperature of each station for each month of the year. 
Am, JOUR, 2 cian Series, Vou. XXVIII. No. 164.—Ave., 1884. 
