138 ECONOMIC GEOLOGY OF AMITY QUADRANGLE, PA. 
[Latitude 40° 09' 12.22". Longitude 79° 48' 54.10".] 
To station- 
Azimuth. 
Back azimuth. 
Log. dis- 
tance. 
71 44 42.6 
O 1 It 
251 34 48.6 
Meters. 
4. 3616006 
SHANNON, ALLEGHENY COUNTY. 
About 1 mile south of Castle Shannon post-office, on a high culti- 
vated knob, on which is one tree about 30 feet northeast of signal. 
[Latitude 40° 21' 33.53". Longitude 80° 01' 26.95".] 
To station— 
Azimuth. 
Back azimuth. 
Log. dis- 
tance. 
Canonsburg 
46 20 22.0 
o / // 
226 14 17. 1 
Meters. 
4. 2656474 
HICKMAN, ALLEGHENY COUNTY. 
On a bald hill in South Fayette Township, 2\ miles southwest of 
Bridge ville, on land belonging to William Hickman, who lives on 
south side of hill. 
[Latitude 40° 20' 52.33". Longitude 80° 08' 44.87".] 
To stat ion 
Canonsburg. 
Azimuth. 
14 35 39.2 
Back azimuth. 
194 34 17. 
Log. dis- 
tance 
Meters. 
4. 0737263 
MERIDIAN MARKS. 
WASHINGTON, WASHINGTON COUNTY. 
Location of station : A few feet north of sidewalk, on the south side 
of and near the southwest corner of the campus of Washington and 
Jefferson College. 
Station mark: A sandstone post 48 by 12 by 12 inches, set about 40 
inches in the ground, in the center of top of which is cemented a 
bronze meridian tablet. 
Distant mark: North of station 482 feet; a sandstone post about 48 
by 12 by 12 inches, set about 36 inches in the ground, in the center of 
top of which is cemented a bronze meridian tablet. 
SPIRIT-LEVEL DATA. 
The contours on the topographic map are based on precise levels 
run by railroad engineers and by the United States Geological Sur- 
vey. During the course of the topographic work numerous bench 
marks were established, and their elevations are given below: 
