THE CONQUEST OF TIME AND SPACE 



forty or fifty feet below the vessel; this enabled the 

 operator to rise instantly to the surface of the water in 

 case of accident. 



'^When the operator would descend, he placed his 

 foot upon the top of a brass valve, depressing it, by 

 which he opened a large aperture in the bottom of the 

 vessel, through which the water entered at his pleasure; 

 when he had admitted a sufficient quantity he descended 

 very gradually; if he admitted too much he ejected 

 as much as was necessary to obtain an equiHbrium by 

 the two brass forcing-pumps which were placed at 

 each hand. Whenever the vessel leaked, or he would 

 ascend to the surface, he also made use of these forc- 

 ing-pumps. When the skillful operator had obtained 

 an equilibrium he would row upward or downward, or 

 continue at any particular depth, with an oar placed 

 near the top of the vessel, formed upon the principle 

 of the screw, the axis of the oar entering the vessel; by 

 turning the oar one way he raised the vessel, by turn- 

 ing it the other he depressed it. 



"An oar, formed upon the principle of a screw, was 

 fixed in the fore part of the vessel; its axis entered the 

 vessel, and being turned one way, rowed the vessel for- 

 ward, but being turned the other way rowed it back- 

 ward ; it was made to be turned by the hand or foot. 



"Behind the submarine vessel was a place above 

 the rudder for carrying a large powder magazine. This 

 was made of two pieces of oak timber, large enough 

 when hollowed out to contain one hundred and fifty 

 pounds of powder, with the apparatus used in firing it, 

 and was secured in its place by a screw turned by the 



[96] 



