Fig. 26. Torreson observing a pilot balloon with 

 the specially designed theodolite loaned by 

 the United States Navy 



Fig. 28. Captain Ault releasing a pilot balloon. These 

 globes ascend at the rate of about six hundred feet a 

 minute and are wafted here and there by the winds 

 they encounter in the upper air 



Fig. 27. Weighing the hydrogen-filled balloon. 

 This is followed in ascent to a height of from 

 two to seven miles in order to plot the air 

 currents 



Fig. 29. A propeller device for reversing deep-sea ther- 

 mometers. This is attached to the bottom-sampling 

 wire, and when the sampler is hauled in, the propeller 

 turns and releases the pin which holds the thermome- 

 ters upright as they plunge to the bottom. Tempera- 

 tures of the ocean bottom have been measured only 

 rarely, although they are of great interest to ocea- 

 nographers 



Fig. 30. Captain Ault, Torreson, and Scott following the 

 pilot balloon 



27 



