- 2 - 



was projected from the top of a tower (fig. 6) at a height of 16 

 feet above the model surface, traced off, (fig. 7), and routed in 

 relief (fig. 8) so that sea level lay 1/4 inch below the land 

 surface. The soundings were then entered on the sea level surface 

 from the same lantern slide and projector, and additional sound- 

 ings were entered from the original data sheets provided by the 

 U. S. Coast & Geodetic Survey. Soundings were realized by routing 

 between carefully drawn contours (fig. 9). The steps were then 

 blended with hand tools (fig. 10), The resulting surface (fig. 

 11) is probably accurate to - 0.015 inch (- 0,25 "foot") verti- 

 cally and - 0,03 inch (i 50 "feet") horizontally. Sea level was 

 established as a level plane (- .005-inch) by means of repeated 

 checks with a precise transit on the pair of rails from vAiich the 

 routing tools were suspended. 



Gravitational (Froude) scaling of the kinematic ratios of 

 time, velocity and discharge ivas used unmodified except at the 

 passes connecting the bays with the Gulf of Mexico. In each of 

 the passes the velocity and the turbulence (measured in terms of 

 eddy diffusion) of flow were initially too high. In order to 

 correct this common situation, roughness was artificially in- 

 creased in the passes by means of wire screens (20 x 20 mesh). 

 Increased roughness in these critical channels not only decreased 

 the velocities so as to agree with the Froude scales but cor- 

 rected to an acceptable degree the characteristics of channel 

 turbiilence as well. To verify the over-all kinematic behavior of 



