For convenience of description and reference, the successive entries in the specimen index have been numbered from 1 to 100, but that is no part of the system: those figures would be replaced in a real index by names and addresses. A preliminary way of obtaining an idea of the differentiating power of an index is to count the number of the different headings that are required to classify a specified number of cases. A table is appended which shows the numbers of the headings in the three alternative methods (1) of noting slopes of all kinds in all digits, (2) of noting slopes of Loops only and in the fore-fingers only, and (3) of disregarding the slopes altogether. Also in each of these three cases taking account of-- (_a_) All the ten digits; (_b_) the fore, middle, and ring-fingers of both hands; (_c_) those same three fingers, but of the right hand only; (_d_) the fore and middle fingers of the right hand. TABLE X. _No. of different index-heads in 100 sets of Finger Prints._ +---------------------------------------------------------------+ | | | Account taken of | | No. of | |------------------------------| | digits | Digits noted. | All |_i_ and _o_| No | | regarded. | | slopes. | in fore- | slope. | | | | | fingers. | | |-----------|--------------------|---------|-----------|--------| | 10 | All the 10 digits | 82 | 76 | 71 | | | | | | | | | Fore, middle, | | | | | 6 | and ring-fingers | 65 | 50 | 43 | | | of both hands | | | | | | | | | | | 3 | Of right hand only | 25 | 16 | 14 | | | | | | | | 2 | Fore and middle of | 12 | 8 | 7 | | | right hand only | | | | +---------------------------------------------------------------+