SECOND ANNUAL REPORT-TOPOGRAPHY AND DRAINAGE. 
41 
the bar which is built across the entrance to a bay. Such bars are to 
be found at the entrance of all the bays, and their removal is one of 
the important problems which confronts the army engineers in their 
endeavor to make the rivers and harbors accessible to shipping. 
On the east coast where the prevailing currents move southward, 
the bars are commonly extended by additions to their southern ends. 
On the Gulf coast of the peninsula the dominant currents appear to be 
in the opposite direction and the bars are usually built by extensive 
additions to their northern ends. The dominant current on the coast 
of West Florida appears to move toward the west, though an east¬ 
ward current of some importance may be inferred from the position 
of the bar at the entrance to St. Andrews Bay. Bars of the kind de¬ 
scribed above are to be seen along the entire coast of Florida wherever 
there are large bays. 
Sounds: — Behind the shore bars on the east coast are narrow 
bodies of shallow water which are commonly known as rivers, though 
they might more appropriately be termed sounds. To this class be¬ 
long such bodies of water as the Halifax and Indian Rivers. As the 
sounds become more nearly surrounded by the growing bars they 
are changed into lagoons which are in turn gradually filled with silt 
and thus transformed into marshes-. Mosquito lagoon and Take 
Worth on the east coast are excellent examples of lagoons, and there 
are numerous marshes along both the east and west coasts. 
About twenty years ago an attempt was made to open a passage 
for steamship navigation by deepening the sounds and lagoons. This 
plan was successful, but in recent years the channels have been allowed 
to become obstructed by sand bars and oyster reefs. In the last few 
years interest in this “inside” channel has been revived, and it is now 
proposed to extend the passage northward to New Jersey. 
Inlets: — Where drainage from the land enters a sound or par¬ 
tially enclosed bay, the water escapes through a narrow passage in 
the bar known as an inlet. As the bars are built under the influence 
of a prevailing current, the inlet is gradually shifted in the direction 
of growth. After a time the opening becomes so obstructed that a 
new inlet is formed by the action of high water. Usually the inlets 
are formed near the head of the bar and their direction of movement 
on the Atlantic coast is southward and on the Gulf coast northward 
or westward. At Jupiter on the east coast an opening is sometimes 
dredged near the north end of the bar and this opening is gradually 
shifted toward the south. It has been found that the inlet remains, 
open much longer when the opening is made toward the northern end 
of the bar than when it is located farther south. 
Tidal Runways:—At ordinary high tide the level of the water in 
the bays and sounds is raised from one to two feet above the normal 
