No. 133.] aa 



Let us suppose the valve No. 6 alone to be open ; the pressure 

 of the water of the river will immediately cause a jet d\au in the 

 cabin : but if, to prevent the invasion of this water, the valve 8 

 be opened at the same time, a portion of the condensed air in the 

 reservoir, rushing into the cabin, will there establish a resisting 

 pressure, capable of overcoming the power of the pressure of tlie 

 water, and from that moment the water of the river will be ex- 

 cluded by the resistance of the pressure of the atmosphere of the 

 interior, and the equilibrium of pressure and resistance will be 

 permanently established. 



The hatchways are then to be opened, and the submarine soil 

 will be exposed to the view and touch of the workmen within, 

 who may anchor upon it, and operate with equal facility, either 

 for mining rocks, or for fishing gold, pearls, &c., &c. 



The mode of reascending is also perfectly simple, and as easily 

 understood as that of descending, and may be performed in about 

 the same time; thus, if it has been necessary, fer example to take 

 in the weight of a thousand gallons of water, to sink the boat to 

 the bottom of the stream, it will be only necessary to expel the 

 same weight of water, with the same pumps, which act in a 

 double capacity, to lighten it sufficiently to cause it to rise to the 

 surface ; or, if it is desired to ascend more suddenly, it will be 

 sufficient to work the bolt to which are attached the chains by 

 which the safety ballast supporters are suspended with the ex- 

 ternal ballast contained on them ; at the same instant, the boat, 

 freed from a weight double that of the water which has retained 

 it at the bottom of the stream, darts to the surface with the speed 

 of ten feet a second. 



Purity of the air breathed by the men in the boat. 

 This fluid, which, by the known effect of breathing, becomes 

 more and more charged with carbonic acid gas, whose deleterious 

 effect upon the lungs is well understood, is purified by means of 

 a pump, which, taking it from the cabin, passes it through a solu- 

 tion of patash, which is kept in a caustic state by means of quick- 

 lime, in which it deposits its carbonic acid, and returns to the 

 men only pure oxygen. 



