Page:Popular Mechanics 1928 01.pdf/50

 



By means of weighted boxes on levers, realistic waves were produced on a quiet pool in the Los Angeles river for depicting a South Sea island motion-picture scene. The disturbers were carefully moved to give the waves a long rolling action, as much like those of the ocean as possible. The illusion was strengthened by imitation tropical vegetation on the beach.

 

Use of chemical ice solved a perplexing water problem in Washington, D. C., recently, saving much time and work and making it unnecessary to shut off the supply to Georgetown. It became necessary to cut in an extension to one of the mains, but this could not be done without first stopping the flow and there were no shut-off valves convenient for that section. To have halted the supply entirely would have resulted in a serious water famine over a large area. An engineer suggested that the pipe be frozen on either side of the place where the break had to be made. Ice and salt were packed about the main but they only chilled the water. Finally, a chemical company was appealed to. They brought out a small box of chemical ice with a temperature of 160 degrees below zero. While the sun shone on the workers, they quickly froze the pipe, the entire process taking less than twenty minutes. The extension was cut in, the sun was allowed to thaw the pipe out again, and a tie-up in service, that might have cost many thousands of dollars and much inconvenience, was avoided.

 

What are said to be the largest casters ever constructed have been made for a sixty-foot lunch car to simplify the task of getting it in and out of difficult places at carnivals, race tracks, fairs, and the like. The units each weigh 425 pounds, are more than twenty-five inches high and the wheel itself is twenty inches in diameter with a six-inch tread. Roller bearings facilitate moving, and there is a special locking device to keep the car steady.



