deduced from Capt. Sabine's Experiments. 



323 



without admitting great errors. This discordance is not to be 

 accounted for by the particular magnitude assigned to the ellip- 

 ticity. It is a real inconsistency that cannot be removed by any 

 probable change in that element. To prove this we need only 

 compare the lengths of the pendulums at the six stations, with 

 the lengths determined on the neighbouring parallels of latitude. 



Having now laid down some principles by which our re- 

 searches are to be guided, we proceed to consider the grounds 

 for adopting the ellipticity assigned to the earth by Captain 

 Sabine in his late work. It must be observed that we do not 

 here discuss the merits of the observer, or the accuracy of his 

 operations. Our reasoning is founded upon the experiments 

 as they have been laid before the public. While the facts 

 remain the same, we do not conceive that our arguments can 

 be controverted. 



The conclusions of Captain Sabine will be found to rest 

 ultimately upon his experiments near the equator. Seven of 

 his stations are within less than 20° of the equatorial circle, 

 viz. 



Station. 



Latitude. 



Pendulum. 





12° 59' 21" S. 



39-02425 



Ascension .... 



7 55 48 



39-02410 



Maranham . . . 



2 31 43 



39-01214 



St. Thomas . . . 



24 41 N. 



39-02074 



Sierra Leone . . 



8 29 28 



39-01997 



Trinidad .... 



10 38 56 



39-01884 





17 56 7 



39-03510 



The extreme irregularity of these experiments is imme- 

 diately apparent. The pendulum at Trinidad, 10°^ from the 

 equator, is very considerably less than the equatorial pendu- 

 lum at St. Thomas. But in order to judge more distinctly of 

 the discrepancies, it will be proper to deduce the equatorial 

 pendulum belonging to every individual experiment. We 

 have to find L from the formula, 



I = L +/sin 2 A: 

 and, although f is not exactly known, yet its value cannot be 

 less than 0-2, nor greater than 0*21 : on these two supposi- 

 tions we obtain as follows : 



Equatorial Pendidum. 



Bahia . . . . 



Ascension . . 

 Maranham . 

 St. Thomas . 

 Sierra Leone 

 Trinidad . . 

 Jamaica . . . 



/= 0-2 

 39-01415 

 39-02030 

 39-01175 

 39-02073 

 39-01569 

 39-01201 

 39*01614 



/=0'21 



39-01364 

 39-02010 

 39-01174 

 39-02073 

 39-01539 

 39-01166 

 39-01519 



Now 



