Fig. 8. (left) In olden days pearl divers may have carried air-filled bladders under 

 the water. Fig. 9. {right) For contrast with the primitive diver, the same artist 

 placed immediately beside it this "modern" diver, equipped with a completely en- 

 closed leather helmet. It was designed to be used in submarine warfare! This and 

 the preceding figure are from a French edition of Vegetius's "De Re Militari" which 

 appeared in 1532. (Courtesy of the New York Public Library) 



Fig. 10. This apparatus, impractical though it obviously was, con- 

 tained the germ of the idea upon which modern diving suits are 

 based — the removal of the confined air and the substitution of 

 fresh. It was designed by Borelli in the seventeenth century. 



(Courtesy of the New York Public Library) 



