While the author would not wish to underrate the excellence of the Thompson- 
-Watt plotter, he must nevertheless admit that the results from this instrument 
shown that the photographic material was of the highest quality. In these cir 
cumstances it would not be expected that the réseau would show any great 
advantage. The geometrical defects of photographic material are due either to 
strains in the supporting base or lack of flatness at the moment of exposure. 
The strains in the supporting base are becoming progressively less and were 
probably very small in this instance, while very great trouble was taken by the 
makers of the 105 camera to develop an efficient film-flattening mechanism. The 
explanation of these results is therefore probably that the pictures were taken 
with a camera that flattened the film properly. Does this foreshadow the demise 
of the réseau without, however, eliminating the glass plate on which it is ruled?