18 



DISCUSSION OF THE VERTICAL FORCE. 



Inequality in the Diuenal Variation of the Vertical Force. 



31 

 33 

 35 

 37 

 39 

 (341 

 43 

 45 

 47 

 43 

 51 

 53 



^^ ' -^ 1842-43. 



91 





93 





95 





697 



14 



99 



16 



01 



18 



03 



20 



05 



22 



07 



24 





26 





28 



40 730 



42 



32 



44 



34 



46 



36 



4S 



38 



50 



40 



52 



42 



54 





756 





58 





60 





62 





64 





66 





- 





/ 



/^ 



"^ 







- 





/ 







^ 



\ 



J 





- 



^ 



J 



/ 



"^ 



\ 



V 



• : 



- 



^ 



/ 



/ 



\ 



> 



• 



- 



■ 













:^ 



- 



1843-44. 



O" 2 4 G 8 10 12 14 16 18 20 22 24" 

 (A.M.) (P.M.) 



Philadelphia time. 



Epoch and Amount of the Principal Maximum and Minimum and Amplitude op the 

 Diurnal Inequality. 



Year. 



Maximum. 



Minimum. 



Amplitude. 



Reading. 



Epocli. 



Reading. 



Epoch. 



Scale div. 



In parts of v. f. 



In absol. meas. 



1841-42 

 1842-43 

 1843-44 

 1844-45 



630'».9 

 687.8 

 715.1 

 741.8 



13" 15"" 

 14 25 

 13 00 

 13 10 



6541.5 

 705.1 

 739.3 

 763.8 



20i> 50'" 



22 10 



23 00 

 20 30 



23". 6 



17.3 



24.2 

 22.0 



0.00078 

 0.00057 

 0.00080 

 0.00073 



0.01000 

 0.00733 

 0.01025 

 0.00932 



Mean 13J 2U, 



21.8 



1 



The epochs are given to the nearest quarter of an hour. 



If we compare the Philadelphia and Toronto curves, we find a general corres- 

 pondence in their form, the early morning secondary in flection being well exhibited 

 at Toronto ; the epochs of the two curves, however, arc shifted by nearly three 

 hours, thus: at Toronto prhicipal maximum at 5 P.M., at Philadelphia 1| P. M. ; 



