I. TERRESTRIAL MAGNETISM. 5 



geodetic latitude and longitude. This I have done, especially in the upper penin- 

 sula of Michigan, taking the Sault St. Mary as the starting-point. But these lati- 

 tudes and longitudes are, at best, only approximate. 



The tabulated results are given in ten columns. In the first, is placed the dip or 

 inclination, and sometimes, also, the variation or declination ; in the second, the 

 number designating the intensity needle; in the third, the epoch of commencing of 

 vibrations of the intensity needles ; in the fourth, the duration of 500 vibrations ; 

 in the fifth, the mean temperature, as indicated by the interior thermometer ; in 

 the sixth, the calculated duration of 500 vibrations, at the standard temperature of 

 60° F. ; in the seventh, the square of the number found in the sixth ; in the eighth, 

 the horizontal intensity, that at Cincinnati, at some specified time, being reckoned 

 1000 ; in the ninth, the total intensity of force in terms of the above-named hori- 

 zontal intensity at Cincinnati ; in the tenth, the total intensity of force, that at 

 Cincinnati being 1000. 



VIII. Series foe 1845. — Cincinnati to the White Mountains. 



Dip. 



Epoch of 

 commencing 

 vibration, 

 brs. min. sec. 



Duration 





Calculated 



of 500 



^ t 



duration 



vibra- 



a s 



at 60°. 



tions. 



H £ 





Square of the 



Horizon- 



Total in- 



preceding. 



tal inten- 



tensity : 





sity. 



hor, be- 

 ing 1000. 



Total inten 



sity : that at 



Cincinnati 



= 1000. 



136. Cincinnati, Ohio-— Lat. 39° 06'. Long. 84° 22' W. April 23, 1845. 



70° 26' 

 Var. 4 4 E. 



1 27 5.4 P 



1112 



81.5 



1110.45 



4 58 03.8 



1349.4 



82 



1347.32 



5 28 02.4 



1344.4 



80.5 



1341.97 



12330992025 

 181.52711824 

 18008834809 



1000 



2986.0 



1000 



137. Marietta, Ohio.— Lat. 39° 26' N. Long. 81° 29' W. April 28, 1845. 



71° 22' 15" 

 Var. 2 25 E. 



1 



52 



57.6 P 



1136.4 



83.5 



1134.66 



12 



22 



03.6 



1380.4 



84.5 



1378.03 



12 



53 



00.8 



1378.8 



85.5 



1375.71 



128745331501957.76 

 189896668091 



18957709969 



'.955.46 



Mean 956.61 



2994 



1002.50 



138. Near Marietta — On a hill below the Muskingum River. April 28, 1845. 



71° 23' 02" 

 Var. 2 25 E. 



6 00 04 P 



1384 



82.5 



1381.82 



19094265124 



950.69 



2982 



999.87 



REMARKS. 



136. Cincinnati, Ohio. — Geology as heretofore described. 



137. Marietta, Ohio. — The above observations were made on Marietta Island. Soil alluvium, under- 

 laid at unknown depths by the rocks of the coal-formation, sandstone, shale, &c. 



138. Near Marietta — Geology: rocks of the coal-formation. Clear. 



