In the first the "S" of "CENTS" is several mm. distant from the right figure "3": in the second it is close to "3". The same remarks apply to the "U" of "UNITED" in its relative position to the left figure "3". In the second cut there is also a square period after the final "E" of "THREE". [Illustration] Looking at cuts 3 and 4 the great variety of spacing between the letters of a word is strikingly apparent in the word "THREE." These differences are easily detected by the 10 mm. unit distance measurement, which has been explained in the introductory chapter of this series of articles. The subjoined diagram proves that there are at least three forms of each word, and, with a little study, the collector will soon recognize the leading types. [Illustration] It seems strange that such great and palpable differences remained unknown until 1892. Quoting from the work of Messrs. Tiffany, Bogert & Rechert, we are, however, informed: "Heretofore it has _not_ been noticed that there are a large number of minor varieties of this die depending on the relative position of the parts." Commenting on Die 26 (three cents rose) the writers make some valuable suggestions, but they discourage the would-be student from going deeper into the subject by the closing paragraph: "So few collectors would be interested in looking for these varieties that it has been thought unnecessary to devote space to them in a general work." In the writer's opinion the most valuable hint thrown out by Messrs. Tiffany, Bogert & Rechert is contained in the following sentence: "If a thread be laid along the lower stroke of the "U" it will pass at different distances from the tip of the nose and fall on different parts of the right numeral, of the space below it, or even as low as the "S" of "CENTS." Why these experts stopped at the gate and did not enter is one of those freaks of the human mind that defies explanation. Certainly the person who made this observation was on the very threshold of discovering a scientific classification of this elusive die. The writer confesses that, after having independently evolved this system of classification, nothing has given him greater satisfaction than to find that the basic idea had been chronicled as far back as 1892. To-day it is well known that a line prolongation along the "U" of "UNITED" establishes five distinct classes. As this system has been fully described in a lecture given by the writer before the Boston Philatelic Society, (April 19, 1904) which lecture has also been published in pamphlet form, and, as this classification has been accepted by the writer of the latest Scott Catalogue, it seems unnecessary to go into the details, especially as the subjoined diagram is self-explanatory. [Illustration]