Abstract
Comparison of complicated chart records is not an easy task, even if great trouble is taken to produce transparent film copies dye-toned to contrasting colours. The lines may cross and re-cross so frequently that the sequence of events is difficult to see. In suchcases superimposition of above-the-line and below-the-line silhouettes is helpful, since it permits both the sign and the magnitude of the error at any point to be readily seen. Photographic procedures are described for making such silhouettes from commercially available materials.
Notes
* Communication No. 2282H from The Kodak Research Laboratories.