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SCIOPT1CON MANUAL 



together by uprights R R, and having longitudinal grooves, 

 i i 1 , in which the slides will fit. A holding spring e crowds 

 in the same direction as the latch, so the slide continues to 

 be pressed against the front side of the grooves. When the 

 slide-frame is in position, held in place by pins II, inserted 

 in the base A, Fig. 43, the glass slide is slipped along the 



Fig. 43. 



grooves i i from right to left, until it occupies the field of 

 the lenses. To change the picture, a second slide is in- 

 serted in the grooves, and pushed after the first by the fore- 

 finger, following in the lower groove. As soon as it reaches 

 the V-shaped latch p, it pushes the latch and framework 

 fr g g l backward, and thus depresses the lever 8. This mo- 

 ,tion raises the stop a, and cuts off the light until the second 

 slide has pushed away the first and occupied the field. At 

 this moment it releases the latch p, when the stop a falls 

 by its own weight, sliding back the framework to its first 

 position, and permitting the light to pass through the pic- 

 ture. These movements can be made instantaneously, and 

 the picture changed during what appears to be a wink of 



