To Balance 

 1 



Camera 

 Lens 7 



i 



A 



.Glass Funnel 



Dumping Cup 



4 



•^—Transparent- Wall Tank 



Figure 1 - Installation Used for Bubble Tests 

 in the Transparent -Wall Tank 



affects the drag of the bubble and produces an error in measuring its size. 

 With careful practice in manipulating the dumping mechanism, all but the larg- 

 est bubbles could be generated without satellites. 



Motion pictures of the rising bubbles were made on 35 ram film. Back 

 lighting was used; a diffusing screen between the light source and the bubbles 

 provided a bright background against which the bubbles were photographed. 

 Film speeds of 2k to 60 frames per second were used. The camera was equipped 

 with a timing light actuated by the 60-cycle current source. This impressed 

 marks on the film from which the exact film speed could later be determined. 

 In photographing the larger bubbles, the camera was located at such a distance 

 as to make the height of the film frame represent about 12 inches in the plane 

 of the bubbles. For the smaller bubbles, the camera was moved closer so that 

 the field included only five Inches. For each position of the camera an ac- 

 curately ruled scale was placed in the plane of the bubbles and a few frames 

 taken to provide a distance scale in measuring bubble positions from the de- 

 veloped film. 



