38 



THE BOOK OF THE LANTERN. 



bottle with a wide neck, such as can be obtained anywhere. 

 Upon this neck fits a disc of lead, perforated with two holes, 

 in which are soldered as fixtures two pewter tubes which 

 bend away from one another at their tops. 



One tube, A, reaches nearly to the bottom of the bottle, 

 and it will be seen that for several inches along its lower 

 part it is perforated with holes. It is this tube which is 

 connected by a rubber pipe to the retort. The dotted 

 line shows the height to which the bottle must be filled 

 with water. The short tube, B, is the delivery tube of 

 the bottle, and is connected with the gas bag. As a gas- 

 tight connexion between the pewter disc and the bottle, 



FIG. 18. 



there is a thick rubber collar, which is tied on the bottle 

 by means of a piece of strong twine. The larger sectional 

 diagram of the bottle neck (see fig. 18) will assist the 

 reader in noting the arrangements described. In order to 

 prevent any chance of water being thrown up into the gas 

 bag, it is as well to place the bag on a table. Let us sup- 



