16 
ARTICLE II. 
On the Phenomena presented by a free Liquid Mass withdrawn 
from the Action of Gravity. By Professor PLarrau, of the 
University of Ghent ; Member of the Royal Academy of Brus- 
sels, &c. &c.* 
[From the Memoirs of the Royal Academy of Brussels, vol. xvi. +] 
1. LIQUIDS being gifted with an extreme molecular mobility, 
yield with facility to the action of forces which tend to modity 
their exterior form. But amongst these forces there is one 
which predominates so much over the rest, that it almost 
entirely masks their action: this force is gravity. This it is 
which causes liquids to assume the form of vessels which con- 
tain them; and it is this also which makes smooth and hori- 
zontal the portion of their surface which remains free. We can 
scarcely recognise, along the contour of this free surface, a slight 
curve which reveals the action of the combined forces of the at- 
traction of the liquid for itself, and of its adherence for the solid 
matter of the vessel. It is only by observing very small liquid 
masses, upon which the relative action of gravity is thus weak- 
ened, that we can see the influence of other forces upon the 
figure of these masses manifested in a very forcible manner: 
thus the small drops of liquid placed upon surfaces which they 
cannot moisten, assume a spherical form more or less perfect. 
Leaving these minute quantities, if we wish to observe liquid 
masses which have freely taken a certain form, we must quit 
the earth, or rather consider the terrestrial globe itself and the 
other planets as having been primitively fluid, and having 
adapted their exterior form to the combined action of gravitation 
and centrifugal force. Theory then indicates that these masses 
ought to take the form of spheroids more or less flattened in the 
direction of their axis of rotation, and observation confirms these 
deductions of theory. Observation shows us also, around Sa- 
turn, a body of annular form, and theory finds, in the combined 
* The Editor has to express his obligation to the Rev. Professor Challis, of 
Cambridge, for his kindness in revising this translation for the press. 
+ Since the time when this memoir was read (January 15, 1842) the author 
has revised his manuscript, and made several important modifications, caused, 
for the most part, by the presentation to the Academy of Sciences at Paris, of 
a treatise by M. Liouville. 
