Nipher — Relation of Direct to Reversed Photographic Pictures. 53 



dition. This would be the case if a punched stencil in card- 

 board were printed upon a sensitive plate. 



The zero condition does not seem to be affected by varying 

 the strength of the bath. If the plate be first placed for a 

 minute in a normal bath, it may then be transferred to and 

 developed in a bath as weak as one-tenth the normal strength. 

 The positive and negative features are then the same as when 

 developed in the normal bath. If the plate is first placed in 

 the weak bath, the solution does not wet the film uniformly, 

 and the plate appears as if it had been attacked by a painter's 

 brush while the gelatine was soft. 



There is little need to lose any valuable landscape exposure 

 entirely if the plate is from the first treated as an over-exposed 

 plate, until its condition is known. 



The plate from which the printing was done is reproduced 

 in Fig. 1, Plate 2.* When exposed for one second at a 

 distance of a meter from a 16-candle lamp a normal nega- 

 tive results from development without restrainer. When 

 the exposure has been increased to 53 m. 20 s. or 3200 

 seconds, the strong light across the walk to the left of the 

 picture begins to reverse, and appear white as a positive. The 

 original slide does not quite cover the sensitive plate be- 

 low. On a narrow strip along the left edge of the picture, 

 the plate is fully exposed to the light. This part also begins 

 to reverse at the same time as the high-light mentioned. In 

 diffuse daylight ten feet from a south window when the sky 

 is as clear as it usuallv becomes in St. Louis, during the win- 

 ter, the picture will begin to reverse with sixteen seconds of 

 exposure. This time varies somewhat with variations in 

 illumination and only rough approximations are possible. 

 This daylight is therefore actinically about 200 times as active 

 as one lamp-meter, which required 3200 seconds to produce 

 the same result. As the exposure increases, other parts of 

 the picture reverse. The light on the monk's lap will finally 

 reverse, and appear white, while the part below in shadow 

 will also appear white, because it is still a negative. 



* The picture was not formed symmetrically on the plate, and the trans- 

 parent border is lacking on one side of the picture. The picture was ob- 

 tained by an artist friend in Southern California. 



