Description of a Portable Diorama. 277 



A B C D, a board to wliich the apparatus is attached. The 

 length of the board is 18 inches, and that of the painted sur- 

 face exposed, G inches, — but the hirger the more striking. 



E F G H, a box for receiving the pictures in front, at E F. 



J K, opening in the side of the box, by which the pictures 

 are introduced successively into a groove in front, behind a 

 border of black velvet, to absorb stray rays from the front 

 light. [In the former construction, as in this, the pictures may 

 be conveniently entered at the side of the box. Both boxes 

 may be mp.de to receive the same pictures.] 



L, front light, compact and bright, in a lantern constructed 

 to direct and confine it to the pictures. If the flame be flat 

 and have not a reflector or a lens, its edge may front the pic- 

 tures. A simple swallow-tail burner, No. 0, gives sufficient 

 light for this scale, The inside of the lantern is done with 

 black japan, flat ; and the sides and bottom, and outside of the 

 bottom, and the supports, so far as necessary, are covered with 

 black velvet. 



M, back light. Swallow-tail No. 1, is sufficient for this scale. 



A circulation of air is admitted to both flames without al- 

 lowing the escape of light. Their covers are moveable, and 

 are represented on the plan as removed. 



N O, opening for receiving into a groove a slight frame of 

 tissue paper, to be used when found of advantage ; particu- 

 larly, when any part of a picture, for example the moon, is 

 made transparent. 



P Q, opening through both sides of the box, for receiving 

 into a groove an opaque slider, of a length equal to about 

 double the breadth of the box, properly pierced, to be drawn 

 gradually across, in order to represent passing gleams of sun- 

 shine ; also for receiving a slider or sliders of tissue paper, 

 painted with various tints in succession, to be drawn gradu- 

 ally across, in order to represent changes of tints, for evening 

 or the like, with the back light, where day is represented by 

 that light, as in fog or snow scenes. The light is not to be 

 allowed to pass over or under those sliders. 



When a slider is used, the tissue paper N O is to be re- 

 moved ; and the open space in front of the back light i.s to be 



VOL. XXXIV. NO. LXVIII. APRIL 1843. T 



