III. 



On the calculation of the oblate 



if the earth, hy means of th 



ohserved lengths of a pendulum in different latitudes, accord 



the method given hij La Pla 



the second volu 



fh 



^'Mecanique Celeste/' with remarks on other parts of the same 



E 



loorTc, relating to the figure of the earth. 



BY NATHANIEL BOWDITCH, LL. D. 



PON looking over Dr. Rees' Cyclopedia, under tlie article 

 Earth, I found he had inserted the elegant method of computing 

 the oblateness of the Earth, or the ratio between the polar and 

 equatorial diameters, by means of the observed lengths of a pen- 



dulum 



second of time in diiferent latitudes 



published by La Place in the second volume of his immortal work 

 the " Mecanique Celeste ;" but he has allowed the application of 

 the formulas to numbers to remain nearly as in the oridnal work,* 



and has moreover committed some 



takes of his own, so that 



the article, as it now stands, is quite imperfect ; and as this Cyclo- 

 pedia has an extensive circulation iu our country, it seems to be 

 proper to notice these errors, in order that a currency may not be 

 given to inaccurate ideas on the subject. It may also be mention- 

 ed as an additional reason for noticing them, that by correctin"" the 



In this work there is a mistake which was alluded to in a note to my pa- 

 per on the total eclipse of 1806, published in the Memoirs of tlic Academy, in the 

 year 1809, vol. 3, p. 21. 



