ie 
XXIII. Observations on the Junction of the Fresh Water of Rivers 
with the Salt Water of the Sea. By the Reverend 
Joun Fiemine, D. D. F. R.S. Eni. 
( Read June 17. 1816.) 
I. is possible, that the following observations may contain 
little that is new to those who are familiarly acquainted with 
the details of the science of Hydrostatics. But as I have not 
met with any remarks on the subject, in the course of my li- 
mited reading, the experiments which were performed, and the 
conclusions to which they lead, are here submitted to the con- 
sideration of the Royal Society. 
When the flux of the tide obstructs the motion of a river, 
the wave has been supposed to produce its effects in the same 
manner as a dam built across a stream. This popular opinion, 
however, appears to have been adopted without sufficient con- 
sideration, as it can only hold true, in those cases, where the 
opposing fluids are of equal density, but never at the junction, 
of opposite currents of fresh and salt water, which are of diffe-. 
rent densities. In this last case, where currents of fresh and 
salt water come in opposition, the lighter fluid, or the fresh 
water, will be raised upon the surface of the denser fluid, or. 
Vou. VIII. P. I. 358 the 
