WONDERS OF THE DEEP 41 



The Williamsons had brought with them two 

 immense glass discs, made in France, each one five 

 feet in diameter and one and a half inches thick, 

 for the observation window. They had also pro- 

 vided themselves with a battery of nine Cooper- 

 Hewitt lights, arranged in a gridiron, each light 

 having two thousand four hundred candle-power, 

 these to be lowered for extra submarine illumina- 

 tion, should that be necessary. These artificial 

 lights, however, were seldom used, owing to the 

 wonderful clearness of the West Indian seas even 

 at considerable depths. 



The Williamson submarine deep-sea tube, it 

 will be remembered, was described as possessing 

 the dual advantages of strength and flexibility. 

 These were obtained by the use of hundreds of 

 overlapping steel scales or plates, hinged together 

 between annular rings of malleable iron about a 

 foot apart, that form the skeleton of the tube. Over 

 this metallic structure was securely fastened a 

 waterproof fabric of canvas and rubber, the result 

 being a permanently open air-shaft down into the 

 sea, a vertical passage-way into which a man may 

 step from the deck of a steamer, and down which 

 he may climb, exactly as one climbs down a ladder, 

 to a depth of hundreds of feet below the 

 surface. 



There is no discomfort from breathing com- 

 pressed air, since there is no necessity to use 

 compressed air. The top of the tube remains open 

 at the deck level like the top of a well, the sides 



