534 M. J. Plateau on some new and curious applications of 



of the flame and on the side facing the apparatus, is an opening 

 of 7 to 8 centimetres in height and 3| centimetres in width ; 

 this iron chimney should, moreover, be surmounted with a 

 smoke-consumer, which prevents the light from ilkuninating the 

 ceiling of the apartment ; lastly, no other lamp or light should 

 be left in the apartment. 



In my insti-ument the transparent discs have a diameter of 27 

 centimetres ; the figm*es occupy a zone comprised between two 

 circumferences, the radii of which are respectively 12 and 5i 

 centimetres, so that the height of the zone is 6i centimetres. 

 As the paper, to be sufficiently transparent, must be thin, and 

 these discs have a somewhat large diameter, I have been obliged 

 to add to their solidity by pasting on the space comprised be- 

 tween the interior limit of the zone and the centre a circle of 

 Bristol-board, and upon the space left beyond the exterior limit 

 of the zone, a circular band of the same substance. The figures 

 were painted in water-colours ; but in the dark parts the colour 

 was applied on both surfaces of the paper in order to increase 

 the strength of the tints, and, for a contrary reason, the parts 

 which should have the greatest light were covered with varnish. 

 I will add, to complete the details relative to my apparatus, in 

 the first place, that the slits cut in the black disc, the edges of 

 which slits converge toward the centre of the disc, have at their 

 furthest extremity from the centre a width of 2 millimetres ; in 

 the second place, the aperture in the screen is 65 millimetres 

 high, and 33 millimetres wide at its upper part, and 1 5 milli- 

 metres wide at its lower part ; and in the third place, when the 

 screen is arranged, its distance to the transparent disc is about 

 7 millimetres. 



The apparatus being now set in motion, the effect will be seen 

 directly and by both eyes ; and although the most convenient 

 position to observe it is exactly in front of the image, it will be 

 exhibited well enough under a little obliquity, so that two or 

 three persons can see at the same time. Moreover, only one 

 image will be absolutely seen, namely that which occupies the 

 erect position. Lastly, this image being the only illuminated 

 object in the apartment, its brightness \vill appear considerable, 

 and effects of light may be thus produced which it would be 

 impossible to attain with the ordinaiy phenakisticope. 



I will here mention, as an example, tlie result which one of 

 my discs gives. The image represents a demon's head inclining 

 towards a coal fire which he keeps in action by blowing, then 

 drawing himself up to take breath, bending again to blow, and 

 so on. This head is seen in-front ; it is about four centimetres 

 high, and is, as well as the fire, on a dark background. When 

 it blows, its cheeks are puffed out, its lips project, its brows are 



