DISSOLVING VIEW INSTRUMENTS. 



377 



conse, or when the bag is full, lurn the stop-cock, to pre- 

 vent gas escaping, unscrew the tube from the purifier, 

 and take the retort off the fire. When required for use, 

 attach the tube from the gas-bag to the lamp, having 

 previously removed any moisture that may have collected 

 in the aperture of the stop-cock in the process of making 

 the gas, which is easily clone by passing a narrow strip 

 of linen, or piece of string, through the orifice. 



Price, with apparatus for producing the gas, $135.00. 



Also, the same lantern with a solar lamp in place of the 

 oxygen lamp and gas apparatus, by which a brilliant disc 

 of eight or ten feet may be made much superior to the 

 ordinary form of dissolving lanterns. Price $120.00. 



Fig. 795. 



The Trinoptric Lantern. (Fig. 795.) This differs 



from the Dioptric Lantern by having in addition to the 



two tubes with lenses and prisms placed at the sides, one 



without a prism placed directly in front of the lantern, 



32* 



