16 



;. riR. 



Base boards for the Sciopticons R. Ufmch 6 inches wide, 

 hinged at the rear, and hooked down in front when not in 

 use, allow their range to be elevated , as a prop placed under 

 the fore part is drawn back. 



These various improvements in the Dissolving Apparatus 

 add greatly to their convenience and efficiency, but not to 

 the price. 



The gas dissolving cock, as before said, is attached by 

 letting its wedge-shaped plate down under wide screw-heads 

 projecting from the rear end of the case ; there is, therefore, 

 no need of screw holes in the plate. Let it be remembered 

 that the hydrogen left to burn in the lantern not in use, is 

 increased or diminished by screwing in or out the small 

 screws in the stops. 



Instead of the legs, shown in Fig. 16, a tripod may be 

 attached to the underside of the case, when preferred, for the 

 greater convenience of transportation. 



A curtain enclosing the apparatus and operator may be 

 suspended from cross bars supported by a rod passing up 

 through the case. 



THE SCIOPTICON ABKOAD. 



The Oil Sciopticon has been extensively introduced into 

 foreign countries (from patterns furnished before my later 

 improvements made their appearance), as may be inferred 

 from the frequent allusions to it in foreign journals. In 

 many cases it has, unfortunately, been modified and de- 

 teriorated by lessening the cost of construction, and by con- 

 forming it to fallacious theories. 



It may not be out of place to insert, in this connection, 



