use. John Perry's SHELF DIVER (Fig. 9.30a) 

 with 25 viewports is an example of this ap- 

 proach. Virtually any direction may be 

 viewed with little or no reorientation of the 

 vehicle. BEN FRANKLIN followed the same 

 approach with 29 viewports, though several 

 of these are so difficult to get to that they 

 are, for all practical purposes, unusable. 



An earlier approach to panoramic viewing 

 by Martine's Diving Bells of San Diego incor- 

 porated plastic wrap-around viewports (Fig. 

 9.30b). This configuration is acceptable on 

 the shallow-diving SUBMANAUT and the 

 view from inside is quite similar to that from 

 within an automobile. Possibly because of 

 the then (1956) unknown characteristics of 



Fig. 9 30 a) SHELf DIVER, b) SUBMANAUT. c) NEMO and d) PC-8 viewing arrangements (a&b Perry Submarine Builders, c&d U.S. Navy) 



456 



