688 TRANSACTIONS OF THE 



By this method, men walking, water rippling and ships sailing 

 may be readily taken in six seconds. 



The rej)roduction of colors from nature by light have been pro- 

 duced by a native American residing in Ulster county, by the 

 name of Hill, but as is usual, his invention has been claimed by 

 a Frenchman known as Niepce de St. Victor, son-in-law of the 

 original discoverer of the Daguerreotype in connection with Da- 

 guerre. Colored prints have been produced by using chloride of 

 stroutian for the red tints, chloride of calcium for the yellow, 

 chloride of nickel for the green, ammonia and chloride of copper 

 for the blue, sulphate of copper and chloride of strontian for the 

 violet. All these substances will color flame; those which will 

 not do not act in the sun's rays. These pictures will not last 

 long unless they are varnished, and placed where there is not a 

 strong light. If your picture is varnished you must examine it 

 with one eye only, as the varnish has the effect of reflecting the 

 light which falls upon it to each eye when they are both used, 

 and from objects in all parts of the room. By closing one eye 

 you shut out much of the reflected light, and the mind is enabled 

 to contemplate the picture with one half of the disturbance; this 

 rule holds good with regard to all varnished pictures. If your 

 gallery has side lights one eye must be closed; if both are used 

 the sensibility to the rays of red invariably give a false coloring. 



In fact, all photographic pictures should be examined with one 

 eye; because they are on a plane surface, and one eye makes it 

 appear as if the objects were in relief; of which there are three 

 kinds in Daguerreotypes and photographs; ocular when both 

 eyes are used, monocular, one eye; and binocular, as in the 

 stereoscope. When we look into this latter instrument, a differ- 

 ent picture is displayed on the black substance in both our eyes, 

 and our mind immediately combines the two flat pictures into 

 one, giving them the solid form they present. If two pictures of 

 different sizes are placed in the stereoscope, the mind forms them 

 into one of an intermediate size; and if two of dilfcrent colors, 

 it is impossible for the mind to combine both; the eye sees the 

 brightest first. 



If there happens to be a bright scarlet object on the picture. 



