162 SCIOPTICON MANUAL. 



firmness by the feet tt, fitting closely into the side grooves 

 when nearing its proper position, and resting flush with the 

 entrance when about in place, leaving about half an inch of 

 the wooden base projecting behind. 



Oxygen gas in a bag between pressure boards weighted 

 by from fifty to one hundred and fifty pounds, or else com- 

 pressed in a condensing cylinder, is put in connection with 

 the oxygen jet at the stop-cock 0, known by its lever- 

 shaped key. The oxygen should be habitually the last to 

 be let on, and the first to be shut off. The mouth of the jet 

 should be kept clear by the broach v, and the tubing should 

 be kept free from kinks. The oxygen arrangement is the 

 same for each of the three burners. 



For the alcohol-burner the wick tube, No. 1, Fig. 37, 

 loosely filled with wicking reaching to the height of the jet, 

 is put in connection, by a piece of rubber tubing, with the 

 adjustable fountain at the side of the lantern. When the 

 fountain is full the wick tube is about two-thirds full. The 

 alcohol is kept to this level by screwing the base with one 

 hand, while the fountain is kept from turning by the other ; 

 taking care not to lift it so as to overrun the wick tube. 



The lime-holder may be supported as in the Oil-light 

 Sciopticon, Fig. 42, but a special holder for No. 1 burner is 

 now preferred, with a half cylindrical stem, which, instead 

 of setting into the socket k, fits over the wick-tube and 

 about the wick, to vaporize the alcohol more freely by its 

 heat. 



For the gas-burner the conical tube g, Fig. 40, is substi- 

 tuted for the wick tube, and connection is made with the 

 house gas fixtures by sufficient length of flexible tubing. 

 This arrangement is to be preferred where house gas is at 

 hand ; it is safe, easily controlled, and scarcely inferior to 

 the mixed jet in efficiency. 



For the mixed jet, connection is made with hydrogen, in 



