88 [Assembly 



The object of having two pumps for each of these uses, is to 

 guard against tliose accidents by which one of them might be 

 rendered unserviceable. This precaution is the more necessary as 

 the pumps are employed in every movement of the submarine 

 boat. Each of tliese pumps, No. 1 aud No. 2, is provided with 

 four cocks, whose use is to produce alternately the expansion and 

 compression of the air, and the expulsion or supply of water in 

 such a manner that they may throw off, or compress, or supply 

 air or water at pleasure, to the reservoirs to which we have already 

 referred ; for the whole operation of the submarine boat depends 

 upon the displacement of a certain quantity of condensed air, and 

 in taking in or throwing off a body of w^ater more or less consi- 

 derable, by working the pumps. Thus, if it is desired to descend 

 to the bottom of the water, the crew, before closing the man-hole 

 by which they entered, will employ themselves in forcing into 

 the reservoir the supply of atmospheric air necessary to balance 

 the weight of the column of water, proportioned to the depth to 

 which it is desired to descend. For the lower it is desired to 

 descend, the more should the air be condensed in the reservoir, 

 so that its resistance may prevent the entrance of the water. 



Then, having thus obtained a sufficient supply of air, the man- 

 hole is to be closed, and we proceed to effect the entire submer- 

 sion of the boat. This operation is iu itself very simple. It will 

 be easily understood, when we say that the men who are inclosed 

 in the interior proceed with the water-pumps, to force into the 

 water chamber, a sufficient quantity of water to overcome the 

 equilibrium which keeps the boat floating, and to sink it to the 

 bottom of the stream. 



Then the boat, by virtue of the law of heavy bodies which only 

 possess the requisite weight to overcome the equilibrium of the 

 pressure and of the specific gravity of water, passes through the 

 liquid at the velocity of one foot a second, and settles gently upon 

 the bottom. After arriving at the bottom, the crew proceed to 

 produce the balance of the atmospheric pressure with the pressure 

 of the water in which they are placed, by means of a small valve 

 which is between the two hatchways at the bottom, and of another 

 valve which is placed behind the pumps, the last of which com- 

 municates with the air-chamber. 



