Trans. Acad. Sci. of St. Louis, Vol. XI. 



Plate IX. 



<£. =- S, o oo, ooo 



X =. 2. <*o 



««wi«#^ 



15. Exposuee, 5.000,000. Illumination. 200. 



16. Exposure, 11,500,000. Illumination, over 200. 

 DIRECT AND REVERSED PHOTOGRAPHY. 



