MR. HENNESSY’S RESEARCHES IN TERRESTRIAL PHYSICS. 
543 
If we represent by X' the coefficient of the variation of gravity at the earth’s surface, 
found by pendulum experiments, and by x" the same coefficient deduced from obser- 
vation of the moon’s inequalities in longitude and latitude, then 
e' and e" being the corresponding ellipticities of the earth’s surface found by the ordi- 
nary theory. Let, in accordance with the latest calculations, 
1 1 * 
t ^ ft 
®~288’ ® ~300’ 
then X, the most probable value of the coefficient of the variation of gravity, becomes 
5 I 
— fyj _ , 
2 293-88 
3rd. To find the numerical value of Q in Section V. (equation 36). From the value 
of ^2 just obtained, 
l-|=-026872, 2+(l-|)j,= 2-11311. 
If we make, in accordance with observation. 
1 1 
^““ 300 ’ ^■“ 289 ’ 
and use the value of X above obtained, 
22e + m — X 8122 . 9'2 
3 J' 5^2=5 X 578 x2880jo~ 
2-07068, 
Q='045253 X sin W2=-0260259. 
GEOLOGICAL DEDUCTIONS FROM THE FOREGOING INVESTIGATIONS. 
(1.) The Stability of the Axis of Rotation of the Earth. 
23. The conclusion arrived at in article 14, shows that if the rotation of the earth 
were originally stable about its axis, it would continue to rotate in the same way for 
ever. 
The action of exterior bodies has been heretofore alone examined in considering 
the question of the position of the earth’s axis of rotation within it. From this exami- 
nation, it results that the action of such bodies would be incapable of producing any 
change in the position of the axis, and hence, if such a change were at all possible, it 
should be produced by some interior action by which the distribution of the particles 
composing the earth would be changed. It is admitted, that if the earth were fluid 
and in rotation with an angular velocity differing but little from its present angular- 
velocity, it would rotate stably about its shorter axis. During the process of its suc- 
cessive solidification, it might happen that the new arrangements of the particles 
* See Humboldt’s Kosmos, Bd. I. s. 174, and Pontecoulant, tome iv. p. 486. 
4 A 2 
