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VI. On the Diving-Bell. By A Correspondent. 



THHE following remarks were written after a conversation 

 -*• with one of the first scientific characters of the present 

 day. That gentleman is so unreserved among his friends, 

 that I could not readily distinguish my own ideas from his. 

 He has, however, published a masterly article on the subject 

 in the Encyclopedia Metropolitana, and is entitled to any ob- 

 servations in which we coincide, perhaps, to more, if worth 

 claiming. 



There are two principal defects in the construction of the 

 diving-bell ; viz. the want of independent locomotion, and the 

 impurity of the air : 



I. It is no doubt possible to invent a submarine boat, in- 

 dependent of assistance from the surface ; but the common 

 bell admits an improvement of this nature. Let us suppose 

 the frame of a carriage without the body, of sufficient weight 

 to sink in water. .Let the bell consist of wood, sufficiently 

 light when containing air to rise with the persons in it to 

 the surface; and let the bell be attached by a rope to the 

 carriage frame. The persons inside by winding up the 

 rope, may draw the bell down to the frame, and can leave it 

 again at pleasure. The frame may be so constructed as to 

 allow the bell to reach the ground; and the frame with the 

 bell attached, can be moved from place to place, by any of 

 the contrivances used for putting chairs and carriages in mo- 

 tion from the inside. This plan is only applicable to a level 

 shore or sea-bank ; in other cases the buoyancy of the bell ad- 

 mits contrivances for keeping it vertical, if the frame should 

 be overturned. An instrument might be contrived for feeling 

 the way before it ; if, for instance, two wheels were connected 

 with the bell by a rod, the rise of the rod in the bell would 

 show the descent of the wheels, while its torsion would show 

 the descent of one of them. 



II. The impurity of the air arises from the following causes : 



1. The vapour generated :— We are told that some stores 

 for gunpowder on the continent are coated with sheets of lead, 

 on which it is found that the vapour settles and runs down the 

 sides, leaving the air dry. This is easily tried, but would per- 

 haps only succeed in a cool state of the lead and air. Some 

 bells are grooved for the same object, but with little effect. 

 Perhaps absorbent substances, such as are used in Professor 

 Leslie's experiments on the air-pump, might here be useful. 



2. The temperature is a great inconvenience : by allowing 

 the hot air to escape at the top of the bell much useful air is 

 wasted. It might be circulated until cooled, through the ad- 



. F 2 joining 



