Illustrations 



I. Man's greatest ups and downs 12 

 z. The first wondcrer 13 



3. The rat-tailed maggot 28 



4. The water spider 29 



5. Medieval French painting of Alexander's Dive 32 



6. Indian painting of Alexander's Dive 33 



7. First printed design for a diving helmet 40 



8. The air-filled bladder of a pearl diver 41 



9. Submarine helmet for warfare 41 



10. An early helmet allowing change of air 41 



I I . A helmet covering the whole diver 44 



12. Impractical but exciting early machines 45 



13. Diving bell with barrel-supplied air 54 



14. Horizontal diving bag 54 



15. The first helmet with pumped air 54 



16. A quite useless submarine boat 55 



17. A submarine with nothing which would work J5 



18. Salvaging cannon from an early diving bell 60 



19. Cruikshank's idea of life in a bell 61 



20. The evolution of human diving ^4 



21. A modern helmet in the Galapagos 65 



22. A seascape from a motion picture film 72 



23. Corals and fish four fathoms down 72 



24. The shrubs of the sea are animals 73 



25. Feathery worms are beautiful as flowers 73 



26. Long-legged arrow crabs creep about 73 



XV 



