J. T. Gardner—Hypsometric Survey of the Territories. 3878 
[A subsequent letter dated October 6th, contains the following 
additional observation.—Epbs. 
I have revisited the summit of the Alleghanies at the crossing of 
the Baltimore & Ohio railroad, and, in the vicinity of Oakland 
station found evidence of a southward movement in the torn up 
Deer Park and Strawberry Summit have given greater facilities 
for observation of superficial deposits than I enjoyed in. 186 
Oakland station is about 30 miles north of the locality where I 
found, in the year above mentioned, a true Canadian boulder of 
real feldspathic gneissoid granite. 
Arr. XLIL—On the Hypsometrie work of the U. S. Geological 
and Geographical Survey of the Territories, ¥. V. HAYDEN, 
U.S. Geologist in Charge; by JAMES T. GARDNER, Geographer 
of the Survey. 
_ Frypiye that Colorado Territory, the field of action des- 
ignated by Congress, was the center of greatest elevation in 
the whole chain of the Rocky Mountains, it was determined to 
en 
lerra Nevada, to discover, if possible, a method of correcting 
the errors of barometrical work, the present system was mt rid 
4000 feet, till 14,000. feet was reached. These stations were 
ycnnected by lines carefully run with the spirit-level, and the 
Wer station is also connected with the sea by spirit-level line. 
Permanent meteorological stations were established at these 
Points, whose observations are taken at 7 A. M., 2 P. M. an 
9 P. M. The observations taken by field parties are classified 
te to heights, and each class is referred to the base sta- 
h The lowest station is Denver, where the U. S. Signal Service 
ave one of their most careful observers. It 1s a 
