THE YARD, PENDULUM, AND METRE. 44! 



every part of the globe in 1830, was led to conclude for 

 the value of the minor or polar axis of the terrestrial 

 spheroid, 41,707,620 feet ; while the late Professor Bessel, 

 pursuing a course similar in its general principle that is 

 to say, using all the measured arcs, great and small, in 

 combination one with another, and taking the most 

 probable mean among the (necessarily) discordant results, 

 obtained by combining them two and two arrived at a 

 value very slightly different, viz., 41,707,314 feet. The 

 mean of these gives, as the result of this mode of proced- 

 ure, 41,707,467. 



(24.) Quite recently, M. Schubert in a very elaborate 

 memoir which appears as part of the ist vol., 7th series, 

 of the Memoirs of the Petersburg Academy, has pointed 

 out the inconvenience, and necessarily discordant results 

 which the combination by pairs of a multitude of small 

 arcs, each of itself insufficient to afford any precise 

 measure of the ellipticity, affords; and assigned his rea- 

 sons for restricting the inquiry in the first instance into 

 the length of the polar axis, as an element unique in 

 itself, and common to all the meridians: deducing it 

 separately from each of the most extensive arcs, the Rus- 

 sian, the Indian, and the French, each taken independ- 

 ently; comparing the three values so obtained, and 

 thence concluding the final result. In this manner he 

 obtains the following three values of the axis, viz. : 



From the Russian arc (of 25 20? in extent) 41, 71 1,019-2 feet 

 Indian (of 21 21' ) 41, 712, 534-2 feet 

 French,, (of 12 22' ) 4 1,69 7, 496-4 feet 



In concluding for these a mean, or final value, M. 



