212 PROGRESS IN COLOR PHOTOGRAPHY. 



the want of success, it appears that there are only two or three dozen 

 good interference color photographs in existence. The delicacy of the 

 lamellar structure is so great that a very slight variation in the condi- 

 tions of the experiment suffices to spoil its result. Thus even the 

 brothers Lumiere, who are certainly the most conscientious students, 

 from a practical standpoint, of interferential color photography, have 

 not beeu able to obtain identical results even "when working with 

 weights of substance as nearly equal as could be determined with the 

 very best balances, when the successive operations were separated by 

 the same intervals of time, and when the experiments were carried on 

 under conditions as nearly identical as possible as regards the temper- 

 ature, the degree of moisture of the air, etc." 1 



Lipprnann's method — although the one giving the most beautiful, 

 complete and accurate results — has still another inconvenience. It is 

 impossible to multiply copies, so that it is necessary to make as many 

 exposures in the camera as there are pictures desired, just as in the 

 old daguerreotype. But perhaps this is not wholly an objectionable 

 feature of this process of Lipprnann's. 



For our part we incline to this view of the matter, and quite agree 

 with Louis Ducos du Hauron. 2 



" If multiplicity has its merits," he remarks, "so also does rarity. If 

 the happy possessor of a painting signed by a great artist were asked 

 if he would be willing to have numerous copies of his picture sent 

 abroad throughout the world, his response might be expected in 

 advance to be vigorous in the negative. To be sure the Almighty 

 made the rose, called the queen of flowers, abundant, but he has at the 

 same time set the diamond in an enchanting solitude." 



Indirect processes of color photography, properly so called, are 

 derived from the method indicated in 1809 by Charles Cros and Louis 

 Ducos du Hauron, who independently conceived the same idea. Many 

 processes noised abroad from time to time are only variations of that 

 invented by these our two compatriots, whose works seem now to be 

 ignored, voluntarily or otherwise, by many. 3 



Indirect photography in colors is based upon the fact that the mix- 

 ture in variable prox>ortions of three colors suitably chosen, and called 

 fundamental colors (red, yellow, and blue), enables the reproduction of 

 all the shades met with in nature. 



The principle of the method is thus defined by Ducos du Hauron : 



"If we decompose into three distinct images — one red, one yellow, and 

 one blue- — the combination images presented by nature, and if each one 



'A and L. Lumiere. Photography in Colors, its Methods and its Results. Com- 

 munication to the French Society of Photography, January 3, 1896. 



z Ducos du Hauron, La Triplice Photographique des Couleurs et l'lmprimerie. 



3 We especially recommend to the attention of those of our readers who desire to 

 know the various researches of Louis Ducos du Hauron the work of his brother 

 Alcide Ducos du Hauron : La Triplice Photographie des Couleurs de l'lmprimerie, 

 published by Gauthier-Villars. 



