360 A. D. Bache on a Magnetic Survey of Pennsylvania 
The declinations were determined with a new Gambey decli- 
nometer belonging to the Girard College: the astronomical ob- 
servations were made with a sextant and vertical circle and 
chronometer. (Grant, No. 3861.) The dip was determined with 
a portable circle by Robinson, and the intensity with Lloyd nee- 
dles by Robinson, and a magnetic bar and cylinder according to 
the method described by me in the American Phil. Trans., vol. ¥, 
18387, in which the vibrations are made in a rarefied medium. 
The full paper, with records, will shortly be printed in the 
Smithsonian Contributions to Knowledge. 
Abstract of results of Declinations, observed in Pennsylvania and adja- 
cent States in 1840-41. 
These observations were made with a Gambey declinometer 
belonging to the Girard College. 
One division (small) of the scale was found equal to 1454, 
as determined in 1844 at Sandy Hook by Lieut. G. M. Bache. 
(See Coast Survey Records.) 1 large division = 60 small divisions. 
The observations were made with telescope direct, with slit to 
the right hand or Z, and with telescope inverted with slit to the 
left or W.; also with needle direct or hairs wp, and with 0D le 
inverted or hairs down. With needle north, W. readings are +, 
E. readings —; with needle south, W. readings are —, 1. Te™ 
ings +. 
Recapitulation of Results for Magnetic Declination, 1840. 
a? 
1. Harrisburg, Penn., July 25, 12"5 W. 
2. Huntingdon, “ July 30, 1 52°3 , 
3. Homewood, near Pittsburg, Aug. 10, 08 ‘0 w 
4, Johnson’s Tavern, near Brownsville, Aug. 17, 0 25°2 ike 
5. Irwin’s Mill, near Mercersburg, Aug. 24, 0 54°4 
6. Baltimore, Md., Aug. 27, 2 16° 
Recapitulation of Results for Magnetic Declination, 1841. 
1. Philadelphia, Penn., July 20 and Nov. 1, 3° 53"°7 Ww, 
2. East a“ MBS 80 
. on, 
3. Williamsport, “ “98 
4, Curwinsville, “ Aug. 1, 
5. Mercer, ‘5 4 
6. Erie, ° eS 
a wooen,. oka“ 3s 
8. Ellicottsville, “ . 
th a“ e 
RPwWnoodeH ww 
. Bath, 
10. Silver Lake, Penn, “ 23, 
Recapitulation of observed Latitudes, 1841. 
Williamsport, Penn., 41° 140 
regi 40 
Curwinsville, “ 57 7 
Mercer, . 41 13°8 
- 42 07°5 
