458 







not possibly be better we had the same base station 

 (London), the same house in London, and the same 

 apartment in the same house : the results at our several 

 stations formed, in fact, one series, of unquestionable 

 relation in every particular. For the solution of the 

 special question which we are now considering they fur- 

 nished me with three groups, remarkably well adapted 

 for the purpose ; the first comprising the five stations 

 nearest to the equator, i. e. between and 10 38' 50" 

 (Trinidad); the second comprising the six stations in 

 England and Scotland ; and the third group comprising 

 the five most northern stations, i. e., between 60 N. 

 and 80 N. The ellipticity severally derived from the 

 combinations of these three groups (which appears to 

 have escaped the notice of M. de Humboldt) was as 

 follows : 



Equatorial and middle latitude - ^TS-T 1 Sabine, 

 Equatorial and high northern - -j-^.-^ > Pend. Exp. 

 High northern and middle latitude jt^.yJ 1825, p. 346. 



It is seen, therefore, that when the experiments 

 are made under suitable and favourable conditions of 

 Uniformity in the apparatus and method, and of well 

 assured relation to each other throughout, the supposed 

 " anomaly" in the ellipticity of the two portions of the 

 quadrant entirely disappears ; each portion of the quad- 

 rant corresponds with the other in the amount of 

 ellipticity which it indicates, and both correspond with 

 the deduction made for the whole quadrant from nine- 

 teen stations distributed over its surface, extending 

 from the equator to a few minutes short of 80 of K 

 latitude. 



