The number of entries under each index-heading varies greatly; reference to the index of 100 sets showing no less than six entries (Nos. 60-65) under one of them, and four entries (Nos. 18-21 and 37-40) under each of two others. Thus, although a large portion of the 100 sets are solitary entries under their several headings, and can be found by a single reference, the remainder are grouped together like the commoner surnames in a directory. They are troublesome to distinguish, and cannot be subdivided at all except by supplementary characteristics, such as the number of ridges in some specified part of the pattern, or the character of the cores. In other respects the difference of merit between the three methods is somewhat greater, as is succinctly indicated by the next table. TABLE XI.--_In 100 Sets._ +-----------------------------------------------------+ | |No. of different index-headings.| | Number of Entries |--------------------------------| |under the same head.| All | _i_ and _o_ | No | | | slopes. | fore-fingers | slope.| | | | only. | | |--------------------|---------|--------------|-------| | 1 | 71 | 63 | 58 | | 2 | 10 | 8 | 9 | | 3 | 1 | 3 | 1 | | 4 | ... | 2 | 2 | | 5 | ... | ... | ... | | 6 | 1 | ... | ... | | 13 | ... | ... | 1 | |--------------------|---------|--------------|-------| | Total | 83 | 76 | 71 | +-----------------------------------------------------+ Hence it is evident that the second method of "_i-o_ fore-finger" is capable of dealing rapidly with 100 cases, but that the method of "no slope" will give trouble in twelve out of the hundred cases. TABLE XII. _Index-headings under which more than 1 per cent of the sets of Finger Prints were registered._ (500 sets observed.)