INTRODUCTION 

 Statement of the Problem 



Performance of useful tasks by man in hydrospace or on the ocean 

 floor safely and efficiently requires good viewing and visibility. Ideally, 

 underwater workers should retain stereoscopic, polychromatic vision in 

 all directions. Furthermore, to optimize physical and mental efforts, it is 

 desirable that the working environment be the gaseous mixture and pressure 

 commonly referred to as "earth atmosphere." Since man immersed directly 

 in water retains neither his terrestrial vision nor atmosphere, it is necessary 

 to provide a protective capsule or habitat. 



Pressure-resistant, transparent capsules can enclose man in a 

 1-atmosphere environment and at the same time not limit his vision in 

 any manner. There are transparent structural materials such as plastics and 

 glass for fabricating such pressure-resistant capsules. The major obstacles 

 to their use are (1 ) the lack of data on the behavior of transparent materials 

 under the biaxial and triaxial compressive stresses generally found in a pres- 

 sure hull under cyclic or long-term external hydrostatic pressure, (2) the 

 lack of proven designs for transparent capsules in which the penetrations in 

 the form of hatches and feedthroughs have been incorporated, and (3) the 

 lack of economical methods for fabricating transparent materials that result 

 in reliable pressure-resistant capsules. 



Because proven transparent capsule designs, methods of building 

 them economically, and data on behavior of transparent material in such 

 capsules under hydrostatic pressure have not been available, no transparent 

 capsules have been built and used in hydrospace to date. If a pressure- 

 resistant capsule incorporating hatches and feedthroughs could be designed 

 to utilize transparent material for its pressure hull, and if such a capsule 

 could be built from a transparent material that safely withstands the stresses 

 generated by hydrostatic pressure, transparent capsules would replace in 

 many cases the steel capsules with small portholes currently utilized in 

 submersibles. 



