VI INTRODUCTION. 



else deflecting them too far apart for both at once to be 

 fully available in a magic lantern. 



4. The Two Parallel Sheets of Flame, an 



inch and a half long, thrown as nearly together as possible 

 without interfering with complete oxygenation, or the 

 escape of the residual gases, are placed iu the direction of 

 the axis of the lenses, so as to fill all the space from which 

 light can pass through both the condenser and the object- 

 ive. Light from any added length would be mostly wasted, 

 and its heat would be troublesome. If the flames were 

 placed across the axis, much of its present extent would 

 fail of reaching the illuminated disk. 



5. The Chimney Cap (J) is held in place by 

 telescoping the portion of the chimney to which it is 

 attached, into the lower portion /. As soon as the flames 

 warm into full vigor, being turned up to about the smoking 

 point, the cap may be lifted some four inches, say by a 

 wooden slide, to avoid touching it with the hand, which 

 will increase the draft, slightly lower and whiten the flames, 

 intensify the light, and more effectually draw off the heat. 

 The light will remain steady and unchanged for two 

 hours and more, without requiring the slightest attention. 



6. The Reflector (H) is outside the flame chamber, 

 and at sufficient distance from the flames not to be injured 

 by them. Its burnished surface is kept from tarnishing by 

 a protecting film. Its place is fixed so as to require no 

 adjustment of distance or direction. It answers the two- 

 fold purpose of a reflector and a door. 



7. The Condenser (pq) is suspended free from con- 

 tact, in a chamber separate from the flame chamber, with 



