In figure 66, we have a print which is similar in many respects to the one described in the preceding paragraph, but here the recurving ridge A continues and tends to terminate on the opposite side of the impression from which it entered. For this reason the pattern is not a loop, but a tented arch. The recurving ridge must touch or pass the imaginary line between delta and core and at least tend to pass out toward the side from which it entered, so that a ridge count of at least one can be obtained.
[Fig. 66]
Figure 67 shows a ridge which enters on one side of the impression and, after flowing toward the center, turns or loops on itself and terminates on the same side from whence it entered. This pattern would be classified as a loop. This pattern should be distinguished from the pattern appearing in [figure 139]. Careful study of the pattern in figure 67 reveals that the core is located at C and the delta D. The imaginary line between these points will be crossed by the ridge forming a loop. In [figure 139], the core is located on the recurve and an imaginary line between the delta and the core does not cross a looping ridge. [Figure 139] is thus classified as a tented arch, as will be seen later.
[Fig. 67]
Figure 68 shows at the center of the print a ridge which forms a pocket. It will be noticed that ridge A does not begin on the edge of the print, but this is of no significance. The ridge A within the pattern area recurves or loops, passing the imaginary line between the delta and the core, and tends to terminate toward the same side of the impression from whence it entered. This is a loop pattern possessing all of the requirements.
[Fig. 68]
In figures 69 and 70, it will be observed that there is a ridge entering on one side of the pattern which recurves and then turns back on itself. These patterns are different from any others which have been shown in this respect but are classified as loops. In each of the patterns the core and delta are marked "C" and "D". The reader should trace the type lines in order to ascertain why the delta is located at point D, and then apply the delta rule.