A 
JOURNAL 
OF 
NATURAL PHILOSOPHY, CHEMISTRY, 
AND 
THE ARTS. 
AUGUST , 1813. 
ARTICLE I. 
Theory of the Tides , including the Consideration of Resist- 
ance. By a Correspondent , E. F. G, H. 
( Concluded from p. IQQ j 
Theorem K« 
T HE oscillations of the sea and of lakes, constituting the oscillators of 
tides, are subject to laws exactly similar to those of pendu- seas and lakes* 
lums capable of performing vibrations in the same time, and 
suspended from points which are subjected to compound regulaF 
vibrations of which the constituent periods are completed in 
half a lunar and half a solar day. 
Supposing the surface of the sea to remain at rest, each point 
of it will become alternately elevated and depressed in com- 
parison with the situation in which it would remain in equilw 
brium, its distance from this situation varying according to the 
regular law of the pendulum (See Theorem F.) : and it will be 
actuated by forces indirectly dependent on, and proportional to 
this distance, so that it may be compared to a pendulum remain- 
Vol.XXXV.--No, 164. a ing 
