Trans. Acad. Sci. of St. Lours, Vol. XL 



Plate VI. 



x ~ %>° * 



9. Exposuke, 24.000. Illumination, 200. 



<r 



s=. 3 6 o c c 



T~ %oo 



10. Exposure, 86.000. Illumination, 200. 



DIRECT AND REVERSED PHOTOGRAPHY. 



