LONGITUDE OF WESTERN BOUNDARY LINE. 



155 



with the treaties it should be. The difference is in favor of Pennsylvania 

 by about 1,000 feet, and it would add to that State, if the same amount 

 continues over the whole stretch of the parallel east to the Delaware 

 river, nearly 42 square miles. Before adopting, however, this conclusion 

 as unexceptionable, it would be necessary to verify the latitude of the 

 boundary in question directly, by employing the best modern means and 

 methods. 



It remains still to examine, at least approximately, the assumption 

 that the boundary marked by the Commissioners is a meridian line. For 

 it is clear, if the former deviates from the true meridian by an angle 

 which may be denoted by a (counted positive to the NW.), the coordi- 

 nates of the monmnent will require the corrections of -f 72' ' sin. a in 

 longitude, and of + 19" sin. a in latitude. For determining the declina- 

 tion (variation) of the magnetic needle, the following observations were 

 made at State Line Station: 











Compass 



Azimuth 





Magnetic 



1865. 





Sid. time. 



Suu's 









meridian 











reading. 



computed. 



concluded. 



h. 



m. 



sec. 





deg. 



min. 



4eg. 



min. 



deg. 



min. 



August 



30. 



16 



59 



35 



Center... . 



78 



ON.W. 



79 



45 N. W. 



1 



45 N. W. 



do 



31. 



5 



45 



52 



do .... 



82 



40 S. E. 



85 



5S. E. 



2 



25 N. W. 



do 



31. 



5 



49 



7 



do .... 



82 



10 S. E. 



84 



31 S. E. 



2 



21 N. W. 



do 



31. 



16 



31 







do 



82 



ON.W. 



85 



39 N. W. 



2 



39 N. W. 



September 3. 



16 



53 



50 



N. Limb.. 



80 



40 N. W. 



83 



55 N. W. 



3 



15 N. W. 



do 



3. 



16 



55 



20 



S. do .. 



81 



5N. W. 



84 



12 N. W. 



3 

 2 



7N. W. 



Mean 













35N. W. 













Now, in running the line, the direction which best agreed with it was 

 found to be, with the same compass, 2° 30' NE. magnetic, wherefore we 

 infer that the angle, above denoted by a, at the utmost can be but very 

 small. 



In this occasion may be pointed out the interesting fact, that the 

 variation of the needle has decreased from 25° W., as it was in 1790, 

 according to the inscription referred to above, to 2| degrees, or at the 

 rate of about 0.3 degree per year. 



In recapitulating, the final result for the position of the boundary 

 monument near the shore of Lake Erie is therefore : 



Latitude 42" 16' 2". 8 North. 

 Longitude 79 • 45' 54".4 in arc, 



= b^ 19°^ S'.eS in time, West of Greenwich. 



