442K. Loomis—Barometrie Gradient in great storms. 
Potsdam as the time of the deposition of the great belt of 
strata represented by the Pre-Potsdam Olenellus horizon of 
Nevada and Lake Champlain. The older St. Johns and Brain- 
tree horizons being correlated, in part at least, with the 
Grand Cafion and Keweenawan series. 
n the Grand Cafion the series is unmetamorphosed, fossil- 
iferous and but slightly disturbed. In Wisconsin the 1,000 
t. Johns, N. B.; the Olenellus horizon of Nevada, Vermont, 
New York, and Newfoundland, and the Potsdam series of Wis- 
consin, New York, Canada, ete., as forming the Cambrian age 
in America, as now known, a subject that will be treated more 
in. detail at some future time. In this arrangement the Lower 
Art. L. — Contributions to Meteorology; by Eu1as Loomis, 
Professor of Natural Philosophy in Yale College. Nine 
teenth paper, with three plates. 
[Read before the National Academy of Sciences, Washington, April 17, 1883.] 
The Barometric Gradient in great storms. 
In his Meteorological Researches for the use of the Coast 
Pilot, Part Il. Mr. Ferrel giyes the following formula for the 
barometric gradient, ° 
Ce 107674 (2n cos y+ Sl (1) 
cos¢(1+°004¢%) P a 
where G denotes the barometric gradient in millimeters pet dere 
gree of a great circle, or 60 geographic miles, ; 
