264 Scientific Proceedings, Royal Dublin Society. 
stated to be generally lowest in the month of December, from 
which time it begins to rise: itis said to attain its greatest 
height in March, at to continue at nearly its maximum level, 
with little variation, for several months. At Las Hermanas, 
between Obligado and San Nicolas, the flood level was distinctly 
visible at 16 feet + inches above the level of the water at the 
time of my visit, 17th of December, 1870. The river was stated to 
have remained at this flood level for eight months. Measurements 
of the river were made at Obligado, and of the various branches 
lower down, including the Ibucuy, so as to ascertain the actual 
quantity of water which was flowing into the Plate. It amounted 
to 520,000 cubic feet of water per second, and this may be con- 
sidered as the minimum volume of the river. I hope to get further 
measurements when the river is in a state of flood. ~ 
“The Uruguay we have not yet had an opportunity of measure- 
ing; but from some particulars of depth and velocity, given by 
Captain Page in his survey of the river for the United States 
Government in the spring of 1855, and by computations from the 
chart prepared for the British Admiralty by Captain Sulivan and 
others, I venture to calculate that it may approximately be rated 
at about 150,000 cubic feet per second in its lowest state, making 
thé total minimum volume of water poured into the River Plate, 
if the condition of low water occur in both rivers at the same 
time, about 670,000 cubic feet per second—a quantity equal to 
the mean volume of thirty-three years passing down the 
Mississippi.” : . 
Mr. J. J. Revy, an Austrian engineer, was employed by Mr. 
Bateman as his assistant in the survey of the River Plate; and he 
subsequently published (without any authority from Mr. 
Bateman) a work* containing results deduced from the observa- 
tions made under Mr. Bateman’s directions, without any suitable 
acknowledgement of Mr. Bateman’s rights of ownership, 
If Mr. Revy’s observations can be relied on, they lead to con- 
clusions of considerable consequence—the most important of 
which is, that the mean velocity of the water-discharge at any 
point of the cross section of a large rwer is simply proportional 
to the depth of the river at that povnt. 
* Hydraulics of Great Rivers. London and New York (1874), 
