30 SCIOPTICON MANUAL. 



thus holding the instrument firmly in place. "When a pair is used 

 for dissolving views, the fronts are thus held in a fixed position, 

 while the rear ends may be spread apart till the disks on the screen 

 coincide. 



o o / Stage and spring for wooden-mounted pictures. The opera- 

 tor standing behind, slides a picture horizontally in at o, letting it 

 bear against the condenser mounting, and letting it project equally 



Fig 



both sides of the cylinder. The picture is drawn out with the left 

 hand, while with the right hand another is made to follow in its 

 place, so as not to show the white disk on the screen. 



p q Condensing lenses. Lenses when taken from a damp or 

 cold place are apt to become covered with moisture, which shades 

 the pictures. It is better when this is likely to be the case, to let 

 the instrument stand in a warm room awhile, or else to draw the 

 lenses apart and dry them before beginning an exhibition. 



r Brass ring, holding the condenser cells suspended in the cylin- 



