AN OCEANOGRAPHIC MODEL OF PUGET SOUND 689 



ing the fine detailing of contours required by the small scale and the 

 complex system of narrow deep channels. A method was developed for 

 casting the model basin in concrete from accurately-contoured hand- 

 carved wood patterns. The contours used, established from the Hydro- 

 graphic Charts of the area, were the elevations of mean high water, 

 75 feet, and 150 feet, and successive ten-fathom depth intervals below 

 mean lower low water. The area was divided into 25 sections for con- 

 venience in preparing the patterns. The contours of each were trans- 

 ferred to white pine lumber planed to the thickness of the contour in- 

 terval. The sections were then cut along the contour line and laminated 

 in exact position. Excess wood was removed and the patterns brought 

 to precise shape by careful hand-carving and sanding with constant re- 

 ference to the charts for soundings between the contour intervals. Small 

 basins were provided upstream from the river mouth for introduction of 

 the river discharge. The wood was brought to a very smooth surface, 

 sealed and varnished (Fig. 2). 



The individual patterns were assembled in an inverted position 

 upon a strongly supported platform 8 by 20 feet, constructed as a base 

 for the model (Fig. 3). Forms were built around the assembled pat- 

 terns with sheet metal separators between the pattern sections to form 

 easily handled blocks. Copper tubing was placed from the outside of 

 the forms to the river basins to carry the fresh water. The patterns 

 were oiled to prevent sticking to the concrete. When the steel reinforc- 

 ing was placed, a coating of smooth cement grouting was applied to the 

 patterns. The forms were then filled to a uniform depth of 15 inches 

 with a standard quick-setting concrete. Twenty-four hours after the 

 concrete was poured, the forms were removed, and the blocks separated 

 and inverted. The patterns were sprung out of the concrete by a meth- 

 od analogous to removing a tightly fitting stopper from a bottle. 



The blocks were reassembled to form the model basin. A bitumas- 

 tic compound was used to seal the joints between blocks. Surveying 

 methods, combined with a latitude-longitude grid on the platform af- 

 forded accurate positioning of the patterns and of the completed sections. 

 The method used insured precise fitting together of the blocks. The 

 joints between the blocks and the minor defects which occurred during 

 the casting were smoothed with plaster of Paris. The basin was finished 

 with several coats of a vinyl resin paint (Fig. 4). 



Tide-Generating Machine 



The requirements for the tide-generating machine were that it 

 closely reproduce natural tides and that it be adaptable to any model 

 of regional waters that might be constructed at these Laboratories. It 



