OF THE HORIZONTAL FORCE. 



51 



Scale 



(C.) SOLAR-DIURNAL VARIATION OP THE HORIZONTAL FORCE; APRIL TO SEPTEMBER, 1840 TO 1845. 

 divisions. I* _ 0.0000365 parts of the horizontal foice. 



Angnt. 



September. 



23456 



7 8 9 10 11 N. 13 14 15 16 17 18 19 20 21 22 23 24" 

 Philadelphia mean time. 





