CHAP, vi.] PHOTOGRAPHY. 291 



adhering to its surface. Placed in this state in the focus of the lens 

 of the camera obscura, it showed after a little time faint lineaments 

 of the picture. To make these features more discernible Niepee 

 formed the idea of plunging the plate into a solution of oil of 

 lavender and petroleum ; and he discovered that " those parts of the 

 film which had been exposed to the light remained almost intact, while 

 the others dissolved rapidly and left the metal bare. After having 

 washed the plate with water the image was visible, the lights 

 and shadows being correctly shown in a word, a positive copy of 

 the picture had been obtained. The lights were formed by the 

 diffused light proceeding from the whitish, unpolished matter of the 

 bitumen ; the shadows by the polished uncovered parts of the 

 silver; it must however be understood, that this resulted when the 

 pure parts of that metal were so situated that they could not send 

 any bright light to the eye by specular reflection. The half-tints, 

 where they existed, resulted from those parts of the varnish which 

 a partial penetration of the solvent had rendered less dense than 

 the parts which had remained intact." (Arago.) Daguerre began by 

 perfecting Mepce's method : he succeeded in reducing the. time of 

 exposure of the plate to the light ; but even then necessitating an 

 action of several hours. We can understand, therefore, that, even with 

 these improvements, it was well nigh impossible to obtain satisfactory 

 reproductions of images in the camera, as objects illuminated by the 

 sun for so long a time had their shadows in one position at the com- 

 mencement of the experiment, and in another at the end. The result 

 was a confusion of images, the tint becoming flat and uniform, and 

 the relief eventually disappearing. 



In any case, the original idea and the glory of inventing photography 

 belong by right, in a great measure, to Mepce, though he had not the 

 privilege of personally enjoying the triumph and sharing with his asso- 

 ciate Daguerre the honour of national gratitude justly bestowed on the 

 two inventors. 1 It was Daguerre who, by the invention of an original 

 method, carried to perfection the new art of reproducing, by light, all 

 the details of a view from nature, such as a landscape or a portrait. 



1 A law was passed in July, 1839, granting to Daguerre and Niepce's son 

 two life pensions of 6,000 and 4,000 francs, on condition of their giving to the 

 public the results of their inventions and discoveries in photography. Niepce, the 

 father, died in 1833. 



U 2 



