398 Capt. Sabine on the Ellipticili/ of the Earth. 



by plants very remotely separated from each other in point of 

 affinity. But while on the subject of teas it may be interesting 

 to observe, that the connrion black Chinese teas consist chiefly 

 of the old leaves of the Tliea viridis, mixed with those of the 

 Camellia Sasanqua or oleifera, and sometimes fragments of the 

 leaves of the Olea Jragrans ; and that the finest teas, whether 

 green or black, appear to be produced by the Thea Bohea, the 

 quality and colour depending solely on the age of the leaves 

 and the mode of preparing them. Although I have long at- 

 tended to the subject, I have never been able to detect, in 

 those teas said to be adulterated, either willow or sloe leaves, 

 or any thing else of British growth. It is probable that the 

 leaves of the species of Camellia be;,fore mentioned may have 

 been taken for sloe leaves. D.D. — Ed in. Phil. Joiirn. 



CAPT. SABIXE ON THE ELLIPTICITY OF THE EARTH. 



The results of different combinations of the experiments on 

 the length of the pendulum which we gave in our last Num- 

 ber, with otherf, are expressed by Capl. Sabine in this table : 



Ellipticitf. 



From Captain Sabine's 13 stations 1 : 288*4? 



From these 13 and 8 stations of the French . 1 : 288*7 



From these IS and 7 British stations 1 : 289*5 



From the mean of 5 stations near the equa- 1 . ^ oco.q 



tor and 6 in Britain J 



From the mean of 5 equatorial and the most \ . , 900.4 



northerly 5 / 



From the 6 British and the 5 northerly . . . 1 : 288*5 



From the general combination of 25 stations . 1 : 289*1 



Mean rT288*7 



'* The attempt," says Captain Sabine, " to determine the 

 figure of the earth by the variations of gravity at its surface, 

 has thus been carried into full execution on an arc of the 

 meridian of the greatest accessible extent; and the results 

 which it has produced are seen to be consistent with each 

 otl)er, in combinations too varied to admit a probability of the 

 correspondence being accidental. The ellipticity to which they 

 conform differs more considerably than could have been ex- 

 pected, from ^^gi J J, which had been previously received on 

 the authority of the most eminent geometrician of the age, as 

 the concurrent indication of the measurements of terrestrial 

 degrees, of pendulum experiments, and of the lunar irregu- 

 larities dependent on the oblateness of the earth." — Qiiarterly 

 Journal of Science. 



LIST 



A 



